The Ultimate Combat Round


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Nolo
July 31, 2007, 01:39 PM
In this thread, I would like to discuss designs and concepts for the ultimate combat rifle round. Please note that I am not considering "exotics" such as caseless ammo, flechettes or other such things, only conventional bullet technology (with the exception of Duplex and Salvo-SqueezeBore rounds, as they are well documented and easily achievable in "normal" firearms). Consider also that this is a thread for discussion, rather than just me babbling my head off. I'm here for input from you, the people who actually know what they're talking about. Also, this thread is solely for the discussion of the cartridges, I'll get to the rifles later. So, basically, unless it has to do with countering an imbalance in a cartridge (like damping recoil), let's save it for later.
So first I'd like to make the observation that different rounds fill different needs, so, in reality, there is no "ultimate combat round", but I'll use that term anyway for simplicity. Thus, I would like to define the requirements that will be put upon the caliber to determine its effectiveness:

For an Assault Rifle:
-The round must have an effective range of at least 400 meters.
-The round must be able to pierce CRISAT body armor at 200 meters.
-30 rounds of this type must weigh no more than 20 rounds of 7.62x51 NATO (i.e. each round must weigh no more than .033 pounds; 1 round of 7.62N weighs approximately .05 pounds, 1 round of 5.56 weighs approximately .025 pounds).
-The round must have recoil no greater than 2 times that of the 5.56x45 NATO.
-The round must be able to produce no less than 1800 ft-lbs of energy from a 16-inch barrel (at the muzzle).

For a Battle Rifle:
-The round must have an effective range of at least 700 meters.
-The round must be able to pierce CRISAT body armor at 400 meters.
-20 rounds of this type must weigh no more than 20 rounds of .30-06 (.06 pounds per round).
-The round must have recoil no greater than that of a .30-06.
-The round must be able to produce no less than 2500 ft-lbs of energy from an 18-inch barrel.

For a "Gun Hose":
-The round must have an effective range of at least 300 meters.
-The round must be able to pierce CRISAT body armor at 100 meters.
-50 rounds of this type must weigh no more than 30 rounds of 5.56x45 NATO (.016 pounds per round).
-The round must have recoil no greater than that of a 9mm Parabellum.
-The round must be able to produce no less than 350 ft-lbs of energy from a 16-inch barrel.

These are the three basic types of combat rifles I can think of. Battle rifles give you power, range and accuracy while sacrificing rate of fire and adding weight. Likewise, "gun hoses" have high rates of fire and light rounds, but they don't have very good accuracy (at range), range or power (per round). Assault rifles are somewhere in the middle, having adequate range and reasonable power, as well as relatively light cartridges. Thus, because the rifles are different, the requirements must be too.
So my first question is. which of these would you recommend for a modern army (i.e. the U.S. Army) to be armed with? My choice would be the Assault rifle, merely because it is in the middle and can be used sufficiently in either of the extremes. Also, I would like to add that, if you have any qualms with the requirements I have set forth, that you tell me. I am certainly able to change them.

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Bobarino
July 31, 2007, 02:13 PM
.260 Remmington

ETA: if its really going to be an "ultimate" combat round, then in my opinion, it should be one round so that it is interchangable throughout the weapon systems. ie: 5.56 can be used in an M249 and the M16/M4. in my opinion, something right in between 5.56 and 7.62 and wouldn't require 14 acts of congress and 6 years worth of R&D to develop would be just right, hence the already available .260 Remmington.

Bobby

edit again: with current technology, your criteria are virtually unattainable for the battle rifle and "gun hose".

Nolo
July 31, 2007, 02:33 PM
I would have to say that .260 Rem. is too large for what it does. You can get better, more compact performance with other cartridge designs, and more powerful rounds with the parent cartridge, .308.

Here are some rounds I was considering, along with some rounds already in use:

-No Picture-
.30-06
-Muzzle Velocity: 3000 ft/s
-Bullet Weight: 165 gr.
-Muzzle Energy: 3300 ft-lbs

http://i200.photobucket.com/albums/aa149/Nolo_photo/308Win_dim.gif
7.62x51 NATO
-Muzzle Velocity: 2800 ft/s
-Bullet Weight: 150 gr.
-Muzzle Energy: 2600 ft-lbs

http://i200.photobucket.com/albums/aa149/Nolo_photo/762x39.gif
7.62x39
-Muzzle Velocity: 2300 ft/s
-Bullet Weight: 125 gr.
-Muzzle Energy: 1500 ft-lbs

http://i200.photobucket.com/albums/aa149/Nolo_photo/223Rem_dim.gif
5.56x45 NATO
-Muzzle Velocity: 3000 ft/s
-Bullet Weight: 65 gr.
-Muzzle Energy: 1300 ft-lbs

http://i200.photobucket.com/albums/aa149/Nolo_photo/5_45x39.gif
5.45x39
-Muzzle Velocity: 2900 ft/s
-Bullet Weight: 65 gr.
-Muzzle Energy: 1200 ft-lbs

http://i200.photobucket.com/albums/aa149/Nolo_photo/ammo.jpg
5.7x28 FN
-Muzzle Velocity: 2350 ft/s
-Bullet Weight: 30 gr.
-Muzzle Energy: 370 ft-lbs

http://i200.photobucket.com/albums/aa149/Nolo_photo/6-5mm_grendel2.jpg
6.5 Grendel
-Muzzle Velocity: 2700 ft/s
-Bullet Weight: 120 gr.
-Muzzle Energy: 1950 ft-lbs

http://i200.photobucket.com/albums/aa149/Nolo_photo/GArem_071305A.jpg
6.8 Remington SPC
-Muzzle Velocity: 2625 ft/s
-Bullet Weight: 115 gr.
-Muzzle Energy: 1800 ft-lbs

http://i200.photobucket.com/albums/aa149/Nolo_photo/.30II.gif
.30-II
-Muzzle Velocity: 2400 ft/s
-Bullet Weight: 125 gr.
-Muzzle Energy: 1600 ft-lbs

http://i200.photobucket.com/albums/aa149/Nolo_photo/7x45mm-1.gif
7x45 Firebrand
-Muzzle Velocity: 2800 ft/s
-Bullet Weight: 135 gr.
-Muzzle Energy: 2300 ft-lbs

http://i200.photobucket.com/albums/aa149/Nolo_photo/6.5x47mm-1.gif
6.5x47 Firebrand
-Muzzle Velocity: 3000 ft/s
-Bullet Weight: 120 gr.
-Muzzle Energy: 2400 ft-lbs

http://i200.photobucket.com/albums/aa149/Nolo_photo/6x43mm.gif
6x43 Firebrand
-Muzzle Velocity: 3000 ft/s
-Bullet Weight: 100 gr.
-Muzzle Energy: 2000 ft-lbs

Basically, this is a comparison of different rounds and scalings of rounds. 6.5x47 and 6x43 are scalings of .30-06 (as best as I could render them), and 7x45 is a scaling of 7.62 NATO. .30-II is a round I created to push armor-piercing payloads at relatively high speeds in carbines, but it could also be used in assault rifles, especially small ones.

Nolo
July 31, 2007, 02:39 PM
Bob, I would also like to say that I was asking which type of rifle a modern army should use, not what caliber. I was going to get to the caliber later.
Also, do not completely discount the "gun hose" idea. If one were able to push out many rounds (say 7-10) in a burst at sufficiently high rates of fire (upwards of 2000 r/m), one would have an extremely effective weapon.

Bobarino
July 31, 2007, 02:48 PM
um you said:

I would like to discuss designs and concepts for the ultimate combat rifle round.

i wasn't discounting your idea at all. but with these criteria,

-The round must have an effective range of at least 300 meters.
-The round must be able to pierce CRISAT body armor at 100 meters.
-50 rounds of this type must weigh no more than 30 rounds of 5.56x45 NATO (.016 pounds per round).
-The round must have recoil no greater than that of a 9mm Parabellum.
-The round must be able to produce no less than 350 ft-lbs of energy from a 16-inch barrel.

its unattainable with current technology. if you lose the weight and recoil resctrictions, you can do it. or if you lose the effective range and AP ability, you can do it. all those things cannot be accomplished at once.

and you asked what we think would be the ultimate combat round. i'm just giving my opinion. your new rounds don't exist yet. like i said, it shouldn't take years of R&D and red tape to field.

as far as the weapon platform, i'd have to go with the HK 416, modified to accept .260 Rem. its familiar, and more reliable that the current DI system in the AR. if it has to fit the current AR/416 platform, i'd go with 6.5 grendel. nice BC in that one. :)


Bobby

Colt46
July 31, 2007, 02:54 PM
For what you are looking for. Too bad the Grendel hasn't really caught on yet. Maybe one day soon, the floodgates will open and some large manufacturer will take a chance on offering it.

RockyMtnTactical
July 31, 2007, 03:11 PM
I don't know about your criteria (everyone has their own idea of the perfect combat round).

Of course mine would have the stopping power and range of a .50cal and the lightweight and recoil of a .22LR. That's not realistic of course, so we have to come to a compromise.

Honestly, I think the 5.56 is a great all-purpose combat round. I can't think of a better one.

M1 Shooter
July 31, 2007, 03:23 PM
I think the old British .280 round developed for the EM2 and the FAL during the 1950's in an assault rifle would be excellent. Of course the 6.8 SPC is a virtual ballistic twin to it, except I believe the .280 used a heavier bullet.

jerkface11
July 31, 2007, 03:24 PM
.250 savage

GunTech
July 31, 2007, 04:30 PM
You can come up with a very good intermediate round if you ditch the requirement that it fit in existing weapons. The 6.5 grendel is a great concept, but falls short because it has to fit in M16 magazines. Obviously, if you allow more special purpose small arms, you can idealize weapons. But the you end up with a bigger logistical mess. To my way of thinking, the best copmbat round is one that can fulfil the largest aaray of mission effectively. I am thinking of something that will work well in a rifle, GPMG DMR and sniper rifle. No round will be perfect, but we can probably do much better.

In another thread, I've already started to spec out a round. I;ve picked the 6.5mm (264) bullet as there exist a number of very high BC bullets that will retain energy, and yet are still light enough to keep recoil suitable for automatic fire. Other calibers worth considering are 6mm and 7mm, both having similar high BC. I did not consider 0.247 due to the lack of suitable existing bullets.

My ideal cartridge begins with several requirements:

6.5 bore - my sample bullets are the 108 Lapua Scenar and 123 Lapua scenar (pri=oven performers in the 6.5 Grendel). These high BC bullets can match or exceed the energy of M80 308 ball at long range given adeqaute velocity

recoil not to exceed that of the AK in 7.62x39. This seems to be about the limit for controllable full automatic fire. Recoil may be attenuated by weapon weight or a muzzle brake, but that is a good starting point

Cartridge must weigh less than the current M80 ball round - the lighter the better

Case should have a body taper of around 1 degree, and a shoulder taper of 20 degrees to make for reliable feeding.

Case head must not exceed the diameter or 0.473 inches (308, 30-06, etc). Smaller is better. Any cartridge derived from an existing one makes things easier.

Pressure should not be excessive, allowing for use in relatively lightly built weapons. Chamber pressure must not exceed 50,000 PSI (223) and a target of 45,000 (7.62x39) is ideal.

More to follow.

Don't Tread On Me
July 31, 2007, 04:31 PM
The United States is focused mostly on terminal type ballistics.

Russia, China and others are focusing on armor piercing characteristics.

In my view, the only thing that counts is making holes in the target. Way too much thought and discussion on this caliber vs. that caliber. Honestly, I don't care if I hit the badguy with a x39, .223 or 5.45 at 200m. He's going down with either at even 600m.

The only problem is the rise of modern body armor. This is a major problem. With modern medicine - non COM shots are rarely fatal. And it has never been easy to go for a headshot (and in some cases due to better helmets, a facial shot).

Doctrine comes into play. With the GWOT, the US is shifting military strategy toward fighting non-state forces. That automatically implies that they will not be equipped with the latest and greatest ceramic and other exotic body armors. Warfare for the US, which is in a way the empire of our era - is going to be combating those who challenge US interests around the world and even back home (militarization of police). It won't be fighting the Soviets in a massive WW2 style war. Any conflict between any of the permanent UN security council members will automatically go nuclear...

The Russians and Chinese though also have interests through 3rd party states. They can envision combating a highly organized and modern state force (US, British, EU) through a client state. They are developing bullets and ammunition that will try and defeat the body armor worn by US soldiers. As time goes on, all these smaller states which have militias, terrorists etc.. will begin to create a huge demand for arms which can be effective against a U.S. soldier. US protection of interests around the world is threatening to Russian/Chinese sphere of influence. So the US is their #1 enemy. Whereas, the U.S.'s #1 enemy is your insurgent, terrorist, guerrilla or just a 3rd world military force.

Remember, the goal is making holes in the target. Not making spectacular wounding effects. Although that is desired too - first and foremost the goal of penetrating to vitals is critical. A bullet like the 5.45 with airpocket and tumbling effects is completely worthless if it can't get through the armor plate worn by the enemy to do its fancy meat-mangling.

That's happening less and less. Many of these Iraqi insurgent videos showing US soldiers getting shot are not fatalities or even close. Good helmets and good body armor is making small arms effectiveness increasingly difficult. It's working to taking them out of the fight, which serves strategic goals, but body count is always better as this has a greater effect on the morale of a nation.


This also has huge gun control implications. Body armor is getting more and more advanced; however, NO NEW innovations in armor piercing cartridges are legal or will ever be legal. Anything new that comes out is deemed military only. So, the State/Authority's defense from your small arms is increasing, and the People/Civilian's ability to project force is decreasing. This is a dangerous development from a liberty perspective. Imagine 25 years from now the JBT's finally achieving the ability to enforce the "law" with no fear of civilian owned small arms due to being covered head to toe in some modern body armor. The balance of power shifts dramatically. Obstacles are bypassed, and as a result - unpopular policies can be enforced. Due to lower risk involved.


For non-body armored threats - I feel the 5.56 is going to stay with us for a long, long time. If the Russians or Chinese can mass produce, cheaply, an effective body armor for 5.56 AND have the nerve to export it to those who are our enemy, you will see calls to replace the 5.56 and to seek a cartridge that can penetrate this armor. I think they will have the nerve to sell it. I think it is a matter of when, not if.

So the ball is in their court. Not ours. We will react to whatever they do. As of right now, the 5.56 produces lethal effects out to great ranges for a small arm.


The ultimate combat round will be that which will work or serve in the near future battlespace.

Nolo
July 31, 2007, 05:10 PM
Actually, Bob, the "gun hose" requirements are perfectly reasonable, and can be realized with a rifle chambered for 5.7x28 FN, which is why it was included with the other rounds.
Out of a 16-inch barrel, 5.7x28 can do about 2500 f/s which gives it a range of about 300 meters easily. It also is able to penetrate CRISAT body armor, and I have no reason to believe that it couldn't do that at 100 meters. As is, one P90 magazine weighs about half that of the STANAG magazines, so that requirement is already achieved. 5.7x28 has about 2/3 the recoil of 9mm Parabellum, so that's done. And, as I stated before, it produces about 370 ft-lbs energy out of the barrel.
And yes, I did say that I was discussing the rounds, but one cannot get to the rounds until one decides what he is doing with them, hence the requirement categories.
And, yes, 6.5 Grendel is an excellent round, and was the inspiration for my 6.5x47 Firebrand round (that is, to create the effect of the Grendel with about 500 f/s added on), but I feel that the Grendel is trying too hard to conform to the current AR-style rifles. I am discounting, in this thread, the ability of ammunition to be used in current rifles, if I weren't, I'd merely go with the Grendel.
As for the British round, it is essentially what we've come full-circle to with the SPC and Grendel cartridges, albeit in smaller for (to fit with "modern" AR platforms).
I figured out a way to evaluate cartridges, especially when mated to their platforms:
Take the size of magazine the rifle will be using (20 for an M14 or FAL, 30 for an M16, 30 for my "dream rifle", 26 for a Grendel rifle) and then multiply that by the muzzle energy of each individual round to find the TME (Total Magazine Energy). Then you take that and divide it by the weight of the magazine (in pounds for me, I like Imperial units) and you get the Energy Per Pound, which you can then use to evaluate your cartridges.

The TME for some cartridges:
5.56 = 1300 x 30 = 39000 ft-lbs
7.62 NATO = 2500 x 20 = 50000 ft-lbs
6.5 Grendel = 1950 x 26 = 50700 ft-lbs
6mm Firebrand = 2000 x 30 = 60000 ft-lbs

This gives you a look at how much power each rifle is dishing out per magazine.
The you just take those figures and divide them by the weight of each magazine (for this experiment, eliminating the weight if the actual magazine and only using the weight of the rounds it contains).

The EPP for the same cartridges:
5.56 = 39000 / (30 x .025 lbs) = 52000 foot-pounds of energy per every pound of ordinance
7.62 NATO = 50000 / (20 x .05 lbs) = 50000 foot-pounds of energy per every pound of ordinance
6.5 Grendel = 50700 / (26 x .033 lbs) = 59090 foot-pounds of energy per every pound of ordinance
6mm Firebrand = 60000 / (30 x .033 lbs) = 60606 foot-pounds of energy per every pound of ordinance

As you can see, surprisingly the 5.56 outperforms the 7.62 NATO in energy per pound of ordinance, but compared to my 6mm design and Grendel (which are very close), it fall significantly short.

Now, this is not the only thing that needs to be considered when choosing a cartridge, but it helps simplify the problem of power. It also tells you how much power a soldier can dish out before he has to change magazines, which is useful. In my opinion, in order to be effective, a 5.56mm rifle has to have a magazine capacity of about 40 rounds to be a true equal to the 7.62, because the soldier can then use the rifle's burst capability (which I would have as a 2-round bursts) with much less sweat on his brow.

Just something to think about.

gipperdog
July 31, 2007, 06:43 PM
How about a platform like the new Israeli Tavor Rifle:
http://www.israeli-weapons.com/weapons/small_arms/tavor/Tavor.html I suggest a rifle like this cause you can utilize a longer barrel length for better terminal ballistics yet still be ergonomic for urban warfare. Something the M16 (better terminal ballistics but too long for urban warfare) & the M4 (better for urban warfare but not so good terminal ballistics) don't do as well because each set of issues for compromise.
You could also chamber this in something like either the 6.5 Grendel or the 6x45. Your combat load would be nearly the same as for the 5.56 & even more so with the 6x45mm cartridge. There the only difference would be in the bullet weight for the combat load. I believe the current combat load it 280 rounds of 5.56 with the 62 gr bullet. If compared to the 6x45, you get an increase for a standard combat load of .92 lbs utilizing the 85 gr bullet. Terminal ballistics are certainly better with the 6mm & target hit probability are better due to less wind drift for the 6mm.

GunTech
July 31, 2007, 06:47 PM
5.7x28 is basically a worthless round, IMHO. It's ballistics are very close to the 22WMR. The 22 hornet looks like a magnum compared to the 5.7. Personally, I don't see the point -particularly when it is possible to build a lock breach 5.56x45 that is virtually the same size as the P90, and can use M16 magazines.

MagPul 5.56 PDW mockup:

http://www.combatreform2.com/defrev/MapPulPDR_FullView_Flash.jpg

Nolo
July 31, 2007, 06:56 PM
I'm not really talking about platforms for rounds just yet. But, yes the TAVOR-21 is a good weapon. However, personally, I like to stay away from plastics, at least until they are truly battle proven.
As for the 5.7x28mm round, it is not worthless, at least not in concept. Its very light weight is what attracts me to it, though, when I finish going down the "gun hose" route I may use another round, either one that I design or one already in production.
But the 5.7x28mm is not worthless, not in quantity.
And for God's sake! Another bloody round that I made that somebody else already thought of! Though to be fair, we are using significantly different bullet weights (I'm talking, of course, about necking up 5.56 to 6mm, which, for me, culminated in the 6x43 Firebrand, and for them created the 6x45mm round. But I use 100 grain bullets, and they use 85 grain bullets. But I came about mine by scaling down the .30-06 round to 6mm and it just so happened that all of the dimensions worked out by necking up 5.56).

elenius
July 31, 2007, 07:07 PM
As you can see, surprisingly the 5.56 outperforms the 7.62 NATO in energy per pound of ordinance, but compared to my 6mm design and Grendel (which are very close), it fall significantly short.


This is not surprising. Since kinetic energy is mass times the square of velocity, light and fast wins over heavy and slow.

gipperdog
July 31, 2007, 07:11 PM
The 6x45 has been around for some time. Sorry. There's even a variation called the 6mm TCU. This was made for Thompson Center Arms for their single shot pistols which I believe was available back in the 1980's. It's the 5.56/.223 necked up to 6mm but with a 40 degree shoulder. Both the 6x45 & the 6mm TCU have been around for a long time with varmint shooters. They typically shoot anywhere from 55 grainers thru 100 grain bullets for the 6mm. Sorry, but I'm not familiar with your 6x43 Firebrand round. With 100 grain bullets, what are you getting for ballistics? 2400 to 2500 fps on an 18" barrel?

As far as plastics being battle proven, wouldn't that already be true via the Glock? A singular case I know but they are great combat weapons, for a pistol. Also, I believe the Travor is being released at this time to front line troops to both Israel & India (for their elite forces). I'm sure the rifle will get battle tested asap in Israel. Seems everything does pretty quick there.

GunTech
July 31, 2007, 07:12 PM
OK, I'll give you the 5.7, as long as you consider the 22 WMR to be a fighting round. 370 ft-lbs isn't much compared to the 1500 of a 223. I haven't fired a P90, but I owned a 5.7. I couldn't see any use for the round other than novelty. The Euopeans may consider it great, but they though the 25ACP was an adequate police round, and the 32 was really something powerful.

Nolo
July 31, 2007, 07:12 PM
It is surprising because 5.56 is often considered underpowered. Especially when seated next to 7.62 NATO.
It was easy to see, however, that that would be the outcome when you look at the energy and weight of both, because a round that weighs half as much as 7.62 puts out more than half the energy.

Jorg Nysgerrig
July 31, 2007, 07:13 PM
So, how many of these 6mm Firebrand loads have you tested? What kind of pressures are you working with to get these velocities out of that size case?

GunTech
July 31, 2007, 07:15 PM
The Tavor looks to be a great rifle, but it still has the ejection port issue. The FN 2000 and Keltec at least have this problem solved. I have yet to be impressed by any bullpup when it comes to tactical shooting. Too many ergonomic issues. Changing mags, for example is a pain.

The Deer Hunter
July 31, 2007, 07:23 PM
I would have to say that the 7.62x54R round pretty much wins here.

Nolo
July 31, 2007, 07:26 PM
Oh, man, this is funny.
Let me put is this way:
6mm Firebrand doesn't exist.
Nor does 7mm Firebrand, or 6.5mm Firebrand.
They are concepts only.
I'm glad that you respect me enough to think that I have the capability to create these calibers, however.
I'm only 16. I don't have any reloading dies, or other such equipment to be able to fiddle around with rounds (I wish I did, though).
All of the performances that I've come up with for the Firebrand rounds (which are named after my *ahem* company, Firebrand Arms) are estimates, based off of math and relationships to other rounds. For instance, my estimates of 3000 fps for the 6mm Firebrand round are based off the fact that the round is an exact "midget" clone of .30-06, which does 3000 fps, and, unless my math is wrong, I see no reason why a smaller version could not retain that velocity. However, I believe my rendering of 6mm Firebrand (as well as the other two) is off, due to the fact that I have to use Paint to create them, and that limits what I can do.
As for GunTech, I do consider .22 WMR to be a fighting round. It (or something near it, I can't remember) was used in the American 180 Submachine Gun, which is where I got the "gun hose" concept from. And no, 370 ft-lbs is not very much compared to 1300 (or 1500, depending on the loading), but 3700 (a ten-round burst of 5.7) is comparable to 3900 (a three-round burst of 5.56).
The Glock, as far as I know, has not seen actual combat service with any military (LE, sure, but their work is alot less harsh on the weapons), nor has any other plastic gun. This is, of course, as far as I know. Feel free to tell me something I don't know.

HorseSoldier
July 31, 2007, 07:26 PM
I think the old British .280 round developed for the EM2 and the FAL during the 1950's in an assault rifle would be excellent. Of course the 6.8 SPC is a virtual ballistic twin to it, except I believe the .280 used a heavier bullet.

280 and 280/30 were throwing, I think 130 or 140 grain projectiles at a lower velocity that 6.8 Rem SPC (Cartridges of the World has the numbers, but my copy isn't handy). 6.8 Rem SPC looks a whole lot like the 280 in terms of foot-pounds, just with a slightly lighter and faster bullet.

gipperdog
July 31, 2007, 07:27 PM
I would have to say that the 7.62x54R round pretty much wins here.

Huh? If the 7.62x54R, then why not something like the 7mm STW & REALLY reach out there to touch someone?

LOL!

GunTech
July 31, 2007, 07:30 PM
Jorg, I had the same question. 50,000 PSI is about the reasonable maximum in most modern assault rifles. Grendel specifically warns users about hot loads in the AR platform.

Nolo, Can you give me exact dimension on your cases? I'll runs them through QuickLoad. In the 6.5x50 round I worked on a couple of years ago, with a water capacity of 37 gn H2O, the best I could do was 2775 fps with 45,000 PSI

The 6.5x47 Firebrand shows a case head size of 10.3mm, or 0.403 inches - which is between 223 (0.383)and 6.8 (0.422). My own 6.5x50 uses a 0.452 casehead and in order to make 3000 fps using requires a chamber pressure of 66,000psi. The 6.5x47 Firbrand would have less case capacity so the pressure must be higher, likely into the 70,000 psi range.

gipperdog
July 31, 2007, 07:41 PM
To reach velocities of 3000 fps from a 6x43 on a 100 grain bullet, your pressures would be way too high for any kind of assault rifle. That's why I asked earlier concerning the 2400 to 2500 fps on an 18" barrel which would be more realistic. I'm not even sure if you can get those velocities with a bolt gun without blowing primers & ruining the brass.
Also, something to consider, utilizing the same case, ie: the 5.56x45 - if you open up the bullet diameter, you can achieve greater velocities with same bullet weights than the parent cartridge can. See the 30-06 compared to the .338-06 with 180 grain bullets. A standard "benchmark" load for the 30-06 with the 180 gr bullet is 2700 fps. With the .338-06, you can achieve this same velocity with the 200 grain bullet, 20 grains heavier. And with the 180/185 grain bullets for the .338-06, you can get about 2900 fps.
For a 16 year old, you write pretty well. Keep it up. You're good.

Nolo
July 31, 2007, 07:41 PM
Okeedokee, lemme see...
For 6mm Firebrand:
Base Diameter: .372 inches or 9.449mm
Length of Case Under Shoulder: 1.533 inches or 38.938mm
Length of Case Under Neck: 1.659 inches or 42.139mm
Length of Case Overall: 1.963 inches or 49.860mm
Shoulder Angle: 17.5 degrees
Diameter of Case Opening: .267 inches or 6.782mm
Weight of Projectile: 100 or 110 grains

I'll get the others later, I've got to go, right now.

By the way, (and I have no idea how this happened) the case length for 6mm Firebrand should be 49mm.

GunTech
July 31, 2007, 07:44 PM
Nolo, what are you using for case design?

I'll run up your cartridge in QD, and make some ballpark guesses. That should get us enough for quickload.

Stay tuned.

GunTech
July 31, 2007, 07:46 PM
Gipperdog, you can get better initial velocities by upsizing caliber for the same bullet weight, but you BC generally goes all to hell, so you pay by losing long range performance. There ain't no free lunch.

gipperdog
July 31, 2007, 07:51 PM
Absolutely! There ain't no free lunch. But some trade offs/compromises still make for great cartridges, like the .338-06. You just have know the limitations (& most limitations are the shooter as most guns/cartridges will outperform the person behind the gun.) LOL!
I once read where someone was simply trying to get ultimate velocities not caring for what the BC was. They were shooting a .375 H&H with something like a 135 grain bullet. They achieved velocities greater than 5000 fps.

Neo-Luddite
July 31, 2007, 08:37 PM
Don't Tread on Me--you tread heavily, but speak the truth regarding the politics of citizen-based R&D.

Interesting thread.

Nolo
July 31, 2007, 09:12 PM
For case design, GunTech, it is merely a .30-06 scaled (not necked) down to 6mm.
Also, I'd rather my cartridge have a high BC than go faster. But .30-II is designed to do just what you were speaking of.

Boanerges57
July 31, 2007, 10:53 PM
the 5.7x28 was developed for a very specific purpose that it serves well. It is a round developed for a Personal Defense Weapon (PDW). It is incredibly accurate out to 200m and was designed to penetrate body armor. It is adequate in urban environments and is fairly easy to control in full auto bursts. It is better than a 9mm in most situations. It is a short range round.
The military has been testing 6.5 Grendel. 6.8 SPC doesnt have good enough performance at range to replace 7.62 NATO and the performance difference at closer (ie, urban ranges) between 6.5 Grendel and 6.8 SPC is so small that 6.5 Grendel could be a viable replacement for both 5.56 NATO and 7.62 NATO.
Im sure there will be a lot of criticism of this but I am hoping to have a comparative side by side firing of the major challengers before Christmas. If anyone is interested in being there it will be near Milwaukee. PM or email me for more info.

GunTech
July 31, 2007, 11:39 PM
Nolo.

I haven't done up your 6x43x, but here what it will taker to get a 100 grain 0.243 bullet up to 3000 fps in 6x45mm. Note pressure and loading densities


Cartridge : 6 x 45 (6-223)
Bullet : .243, 100, Sierra SPBT 1560
Cartridge O.A.L. L6: 2.260 inch or 57.40 mm
Barrel Length : 18.0 inch or 457.2 mm

Predicted Data for Indicated Charges of the Following Powders.

Matching Muzzle Velocity: 3000 fps or 914 m/s

These calculations refer to your specified settings in QuickLOAD 'Cartridge Dimensions' window.
C A U T I O N : any load listed can result in a powder charge that falls below minimum suggested
loads or exceeds maximum suggested loads as presented in current handloading manuals. Understand
that all of the listed powders can be unsuitable for the given combination of cartridge, bullet
and gun. Actual load order can vary, depending upon lot-to-lot powder and component variations.
USE ONLY FOR COMPARISON !

1 loads produced a Loading Ratio below user-defined minimum of 90%. These powders have been skipped.

Powder type Filling/Loading Ratio Charge Charge Vel. Prop.Burnt P max P muzz B_Time
% Grains Gramm fps % psi psi ms
--------------------------------- -----------------------------------------------------------------
Norma URP 132.2 31.5 2.04 3000 99.3 98037 12731 0.765 !DANGEROUS LOAD-DO NOT USE!
Winchester 760 125.2 32.0 2.07 3000 97.4 98463 13053 0.764 !DANGEROUS LOAD-DO NOT USE!
Ramshot Hunter 127.7 32.8 2.13 3000 98.0 98565 13130 0.762 !DANGEROUS LOAD-DO NOT USE!
Ramshot BigGame 128.9 31.1 2.01 3000 99.9 98812 12439 0.764 !DANGEROUS LOAD-DO NOT USE!
SNPE Vectan SP 11 125.0 31.1 2.02 3000 99.9 99051 12421 0.764 !DANGEROUS LOAD-DO NOT USE!
Alliant Reloder-22 139.3 34.0 2.20 3000 94.9 99057 13684 0.759 !DANGEROUS LOAD-DO NOT USE!
Raufoss RA15 139.3 34.0 2.20 3000 94.9 99057 13684 0.759 !DANGEROUS LOAD-DO NOT USE!
Alliant Reloder-25 145.2 34.9 2.26 3000 98.0 99092 13803 0.759 !DANGEROUS LOAD-DO NOT USE!
Winchester WXR 143.2 34.2 2.21 3000 94.7 99190 13703 0.759 !DANGEROUS LOAD-DO NOT USE!
Accurate 4350 136.3 31.5 2.04 3000 99.3 99336 12519 0.767 !DANGEROUS LOAD-DO NOT USE!
Vihtavuori N560 138.7 34.2 2.22 3000 92.2 99417 13925 0.759 !DANGEROUS LOAD-DO NOT USE!
Hodgdon H4350 131.0 31.4 2.04 3000 98.4 100154 12835 0.756 !DANGEROUS LOAD-DO NOT USE!
IMR 4831 142.4 32.9 2.13 3000 98.5 100994 12725 0.758 !DANGEROUS LOAD-DO NOT USE!
Hodgdon H414 121.7 31.3 2.03 3000 98.2 101132 12840 0.764 !DANGEROUS LOAD-DO NOT USE!
IMR 4895 124.5 29.1 1.88 3000 100.0 101333 11598 0.753 !DANGEROUS LOAD-DO NOT USE!
Bofors RP11 ~approximation 123.3 29.7 1.93 3000 99.9 101339 12286 0.766 !DANGEROUS LOAD-DO NOT USE!
Raufoss RA11 123.3 29.7 1.93 3000 99.9 101339 12286 0.766 !DANGEROUS LOAD-DO NOT USE!
Alliant Reloder-15 123.3 29.7 1.93 3000 99.9 101339 12286 0.766 !DANGEROUS LOAD-DO NOT USE!
Norma 203B 123.8 29.9 1.94 3000 100.0 101459 12204 0.765 !DANGEROUS LOAD-DO NOT USE!
Lovex S070 136.8 32.5 2.10 3000 99.0 101716 12621 0.763 !DANGEROUS LOAD-DO NOT USE!
Hodgdon BL-C2 116.1 30.6 1.98 3000 100.0 102251 12032 0.763 !DANGEROUS LOAD-DO NOT USE!
Norma MRP 2 148.2 35.8 2.32 3000 93.1 102566 13908 0.751 !DANGEROUS LOAD-DO NOT USE!
Winchester 748 114.1 29.6 1.92 3000 100.0 102611 11583 0.759 !DANGEROUS LOAD-DO NOT USE!
Alliant Reloder-19 137.2 33.1 2.15 3000 95.5 102990 13192 0.752 !DANGEROUS LOAD-DO NOT USE!
Norma 203 old 124.8 30.4 1.97 3000 100.0 103549 11903 0.764 !DANGEROUS LOAD-DO NOT USE!
Accurate MAGPRO 138.4 35.5 2.30 3000 90.3 104526 13736 0.748 !DANGEROUS LOAD-DO NOT USE!
IMR 3031 125.4 28.3 1.83 3000 100.0 104570 11009 0.757 !DANGEROUS LOAD-DO NOT USE!
Bofors RP14 ~approximation 138.2 33.4 2.16 3000 95.6 104621 13088 0.748 !DANGEROUS LOAD-DO NOT USE!
Rottweil R903 131.7 30.5 1.98 3000 100.0 104963 11777 0.760 !DANGEROUS LOAD-DO NOT USE!
Somchem S355 128.8 30.4 1.97 3000 100.0 105162 11900 0.759 !DANGEROUS LOAD-DO NOT USE!
Hodgdon H380 124.0 30.6 1.98 3000 99.4 105393 12296 0.757 !DANGEROUS LOAD-DO NOT USE!
SNPE Vectan SP 9 121.2 30.2 1.96 3000 100.0 105526 11947 0.754 !DANGEROUS LOAD-DO NOT USE!
IMR 4320 125.9 29.9 1.94 3000 100.0 105739 11766 0.746 !DANGEROUS LOAD-DO NOT USE!
PB Clermont PCL 516 120.3 30.9 2.00 3000 99.4 106345 12240 0.751 !DANGEROUS LOAD-DO NOT USE!
PB Clermont PCL 507 117.8 29.7 1.92 3000 100.0 106399 11627 0.753 !DANGEROUS LOAD-DO NOT USE!
Somchem S385 137.4 33.7 2.18 3000 96.9 106471 12664 0.747 !DANGEROUS LOAD-DO NOT USE!
Ramshot TAC 117.0 29.6 1.92 3000 100.0 106529 11603 0.752 !DANGEROUS LOAD-DO NOT USE!
Accurate 4064 133.3 30.1 1.95 3000 100.0 106726 11234 0.767 !DANGEROUS LOAD-DO NOT USE!
ADI AR 2209 135.7 32.6 2.11 3000 95.3 107115 12937 0.742 !DANGEROUS LOAD-DO NOT USE!
Somchem S321 116.4 29.9 1.94 3000 100.0 107299 11638 0.754 !DANGEROUS LOAD-DO NOT USE!
Accurate 2520 120.7 30.0 1.95 3000 100.0 107637 11202 0.756 !DANGEROUS LOAD-DO NOT USE!
Norma 204 130.6 32.5 2.11 3000 95.6 107823 12765 0.741 !DANGEROUS LOAD-DO NOT USE!
Bofors RP4 ~approximation 134.8 32.5 2.11 3000 95.6 107823 12765 0.741 !DANGEROUS LOAD-DO NOT USE!
Raufoss RA4 134.8 32.5 2.11 3000 95.6 107823 12765 0.741 !DANGEROUS LOAD-DO NOT USE!
IMR 7828 SSC 136.4 33.8 2.19 3000 92.9 108027 13307 0.740 !DANGEROUS LOAD-DO NOT USE!
IMR 7828 144.2 33.8 2.19 3000 92.9 108027 13307 0.740 !DANGEROUS LOAD-DO NOT USE!
IMR 4350 139.0 32.1 2.08 3000 95.1 108189 12687 0.743 !DANGEROUS LOAD-DO NOT USE!
Rottweil R905 141.7 33.9 2.20 3000 93.1 108278 13014 0.740 !DANGEROUS LOAD-DO NOT USE!
ADI AR 2208 127.5 29.9 1.93 3000 99.9 108498 11879 0.745 !DANGEROUS LOAD-DO NOT USE!
Hodgdon VARGET 127.9 29.9 1.93 3000 99.9 108498 11879 0.745 !DANGEROUS LOAD-DO NOT USE!
Vihtavuori N530 116.9 28.4 1.84 3000 100.0 108556 11398 0.748 !DANGEROUS LOAD-DO NOT USE!
Hodgdon H4895 128.7 30.0 1.95 3000 100.0 108654 11237 0.743 !DANGEROUS LOAD-DO NOT USE!
Accurate 3100 148.9 34.0 2.20 3000 98.2 109272 12211 0.740 !DANGEROUS LOAD-DO NOT USE!
SNPE Vectan SP 10 111.6 28.8 1.86 3000 100.0 109402 11137 0.748 !DANGEROUS LOAD-DO NOT USE!
PB Clermont PCL 508 111.6 28.8 1.87 3000 100.0 109656 11123 0.747 !DANGEROUS LOAD-DO NOT USE!
Somchem S341 120.3 30.9 2.00 3000 100.0 109734 11549 0.744 !DANGEROUS LOAD-DO NOT USE!
IMR 4064 129.4 29.5 1.91 3000 100.0 109828 11594 0.744 !DANGEROUS LOAD-DO NOT USE!
Hodgdon H335 111.3 29.3 1.90 3000 100.0 109905 11150 0.745 !DANGEROUS LOAD-DO NOT USE!
Norma 201 118.0 29.1 1.89 3000 100.0 110108 11403 0.751 !DANGEROUS LOAD-DO NOT USE!
ADI AR 2213 137.7 33.6 2.18 3000 93.0 110126 13228 0.736 !DANGEROUS LOAD-DO NOT USE!
Norma 202 123.2 29.3 1.90 3000 100.0 110535 11090 0.747 !DANGEROUS LOAD-DO NOT USE!
Accurate 2495 125.5 28.6 1.86 3000 100.0 110802 10775 0.760 !DANGEROUS LOAD-DO NOT USE!
SNPE Vectan Sp 7 113.3 29.3 1.90 3000 100.0 111203 11096 0.751 !DANGEROUS LOAD-DO NOT USE!
ADI AR 2219 112.0 27.9 1.81 3000 100.0 111707 10786 0.740 !DANGEROUS LOAD-DO NOT USE!
Hodgdon H322 119.1 27.9 1.81 3000 100.0 111707 10786 0.740 !DANGEROUS LOAD-DO NOT USE!
Ramshot X-Terminator 114.2 28.5 1.85 3000 100.0 111790 10927 0.743 !DANGEROUS LOAD-DO NOT USE!
Rottweil R902 126.0 29.3 1.90 3000 100.0 112022 11244 0.747 !DANGEROUS LOAD-DO NOT USE!
Hodgdon Retumbo 152.3 36.9 2.39 3000 95.8 112249 14030 0.735 !DANGEROUS LOAD-DO NOT USE!
Rottweil R907 130.9 31.0 2.01 3000 97.7 112840 12210 0.741 !DANGEROUS LOAD-DO NOT USE!
IMR 4007 SSC 126.8 31.0 2.01 3000 97.7 113007 12200 0.740 !DANGEROUS LOAD-DO NOT USE!
Nitrochemie A/S 0300 110.5 27.4 1.77 3000 100.0 113052 10564 0.742 !DANGEROUS LOAD-DO NOT USE!
Rottweil R901 123.3 28.3 1.83 3000 100.0 113222 10925 0.749 !DANGEROUS LOAD-DO NOT USE!
Accurate 2460 114.9 29.7 1.93 3000 100.0 113595 10966 0.746 !DANGEROUS LOAD-DO NOT USE!
Rottweil R904 137.2 32.6 2.11 3000 94.9 113812 12404 0.731 !DANGEROUS LOAD-DO NOT USE!
Vihtavuori N540 127.2 31.0 2.01 3000 100.0 114418 11664 0.738 !DANGEROUS LOAD-DO NOT USE!

Nolo
August 1, 2007, 12:07 AM
Hehehe... 90,000-100,000 psi. That's alot. However, I did say before that the case for 6mm should be 49mm long. I don't know how I got 43mm before.
Some other cartridge dimensions:

For 6.5mm Firebrand:
Base Diameter: .403 inches or 10.236mm
Length of Case Under Shoulder: 1.662 inches or 42.215mm
Length of Case Under Neck: 1.799 inches or 45.695mm
Length of Case Overall: 2.127 inches or 54.026mm
Shoulder Angle: 17.5 degrees
Diameter of Case Opening: .290 inches or 7.366mm
Weight of Projectile: 120 grains

For 7mm Firebrand:
Base Diameter: .434 inches or 11.033mm
Length of Case Under Shoulder: 1.433 inches or 36.407mm
Length of Case Under Neck: 1.573 inches or 39.942mm
Length of Case Overall: 1.851 inches or 47.016mm
Shoulder Angle: 20 degrees
Diameter of Case Opening: .283 inches or 7.184mm
Weight of Projectile: 135 or 150 grains

GunTech
August 1, 2007, 12:23 AM
Boanerges57

I understand the rational for the 5.7x28. It may be able to penetrate armor, but from personal experience I can tell you it lack lethality. At 100 yards I has several failures on prarie dogs and rabbits.

A 32 gn bullet going 2350 fps (SS190 from a P90) simply doesn't have adequate energy for military purposes, IMO - even if it does go through a vest. Most of the very light 224 size bullets have a BC of around 0.1. Being generous, I gave the SS190 a BC of .2. At the muzzle, the SS190 has a whopping 382ft-lbs of energy. This is equal to 124gn 9mm ball, true. Of course 9mm ball has an extremely poor record against people - people without the benefit of armor. It should be noted that the 9mm pistol is significantly more compact that the P90. In an apples to apples comparison, the SS90 fired from a FiveseveN manages 2100fps for 313ft-lbs of energy. You are tradining penetration for energy. And by the way, bulletys lose velocity penetrating body armor. Even rounds that penetrate may give up 50% of their energy or more.

By contrast, a 5.56x45 fired from a 10 inch barrel will also make 2500 fps with a 55gn M193 bullet for 764ft-lbs, or 2440 in a 10 inch barrel with M855 62gn for 820ft-lbs.

It is quite possible to build a PDW the size of the P90 that uses 223 ammunition and standard M16 magazines that outclasses the P90 and FiverseveN in every conceiable way. Even the 22 hornet is superior ballistically.

Nolo
August 1, 2007, 12:27 AM
Here is the updated 6mm Firebrand picture:

http://i200.photobucket.com/albums/aa149/Nolo_photo/6x49mm.gif

Nolo
August 1, 2007, 12:31 AM
I'm talking not about performance with the SS190 round, I'm talking about weight!
Yes, I know that the 5.7mm FN round is horribly weak when compared to the 5.56, but not when you use it in quantity! I'm talking about dishing out 7-10 of these rounds at upwards of 2000 rounds per minute! And you can do that adequately because the 5.7mm FN is so much lighter than the 5.56mm, so you can carry 75- or 100-round magazines. Plus, I'm not talking about using the SS190 itself, I'm just using it as a representative of that group.
Now tell me that isn't useful. Sure, it lacks range, but it's darn good for CQB, at the very least!

Nolo
August 1, 2007, 12:36 AM
Don't Tread On Me, that's exactly why I use a Mosin-Nagant. If the the Feds (or anybody else) ever go haywire, I'm fairly certain that my 7.62x54R bullet will be able to penetrate their vests. If you're worried about that, become a rifleman. A real rifleman. Get a friggin' Garand.

dodging230grainers
August 1, 2007, 12:46 AM
interesting stuff, Nolo. I'm only a year older than you and you lost me a few times with the math. Then again I suck at math. Oh, and as for the Glock seeing military service, the Austrian army was the first to adopt it, and they still use it.

As for the ultimate assault rifle combat round in current production...easy.

7.62x39mm Soviet.

And Nolo, I agree that the mosin nagant is the ultimate SHTF rifle. Hey, it won Stalingrad (with cannon fodder techniques)...

Good to see two people from the same generation love the mosin =D

Nolo
August 1, 2007, 12:50 AM
Yes, the Glock has seen service, I know the Austrian Army uses it. But when was Austria in a war? I think the last time was WWI (if you don't count WWII, it was part of Germany during that one). So the Glock has seen service, it hasn't seen combat, as far as I'm aware. Plus, we haven't really seen the true test of plastics: the test of time. Will they wear out? Do they create structural problems later in life? Until I see that they are truly successful, I will stick to the good ole' mostly metal guns. (By the way, it's not the aesthetics of them, I like the way the G36 looks just fine.)

Nolo
August 1, 2007, 12:53 AM
It's an excellent rifle, and it doesn't have all that Mauser pedigree behind it, which I like. :D

dodging230grainers
August 1, 2007, 12:54 AM
Outside of a small number of contractors in Iraq, I'd say you're right about the Glock seeing combat. It'd be interesting to see what they have to say about how the Glock holds up in the "sandbox".

I think the soviets had it right when it came to small arms. They're the best in the world for the most undesirable purposes.

GunTech
August 1, 2007, 01:01 AM
Nolo, even lengthening the 6x45 to 49mm, to get 300 with a 100gn bullet generates a pressure of 72,000psi. Your cartridge has a smaller base and thus less volume, leading to higher pressure.

I was able to get 3000 fps with suitable (although high) pressure by starting with a 7.62x39 case and increasing the case length to 49mm. By dropping bullet weight down to 90gn (Sierra 90gn FMJBT), pressure was reduced to under 50,000psi. A charge of 38.5gns of H5350 will accomplish the velocity required with a loading ration of 98.6%

Nolo
August 1, 2007, 01:12 AM
Interesting. Well, what velocity would the 6x49mm cartridge get as is?
It seems that the velocity may be scaling with the cartridge, something that I should have expected. If it is, I can only expect about 2300 f/s with the 6x49 Firebrand, which would be highly disappointing to me. And I scaled the cartridge diameter correctly, I believe, but let me double check.
Yep, it's correct, 9.46mm for the cartridge base. That's the base for a scaled down .30-06. Damn, I sure hope the speed is not scaling with the cartridge. That would suck. And, yes, I was thinking about necking up the 5.45x39mm cartridge (which is highly similar to the 7.62x39mm, but not identical) to 6mm, but I was not thinking of lengthening it. That would, in my opinion, make the cartridge have a EPP of not greater than the Grendel (due to the increase in weight), which is the EPP I'm trying to beat.

By the way, yes I did think of scaling the bullet weight of the .30-06, and the weight I have now is actually under the scaled weight (118 grains).

Nolo
August 1, 2007, 01:25 AM
I just found a neat round:
6mm AR. It's basically a 6.5 Grendel necked down to 6mm. It pushes a 105 grain bullet with a better than .5 ballistic coefficient out the barrel at 2900 fps. That beats the Grendel in EPP, I'm sure.
Now why aren't we getting performance like that out of 6x49mm? It seems to me that there's not internal spatial difference. Is it because pressure is greater inside the longer cartridge of the 6x47? If so, let's just neck up 5.45x39mm!

kaizer
August 1, 2007, 01:32 AM
What about the .243? Shoots flat as an arrow and will cover the 400 yards no problem. Easily adapted to the AR platform. More punch than 5.56

Frog48
August 1, 2007, 01:33 AM
I've taken an interest in the 6.5 Grendel lately.

Hopefully its not just a passing fad, but unfortunately aftermarket support (thus far) has been minimal at best, so it could eventually be nothing more than a novelty.

zinj
August 1, 2007, 02:00 AM
I think .250-3000 Savage would make an excellent service rifle round. It can be loaded with bullets from 87 to 115 grains, has a standard .473in case head, is fairly compact and has moderate recoil. Unfortunately it was invented in 1915 and doesn't have a sexy metric designation, so it would never be adopted.

GunTech
August 1, 2007, 11:18 AM
Anything with a 473 case head is going to be big, defeating the requirement for a light round.

The issue with the grendel as a fighting round is the sharp shoulder and the almost non-existant body taper. It's really a target round - basically an opened up 6mm PPC.

The problem with a lot of these rounds is if you restrict yourself to an M16 magazine, you are basically limited in performance. You can increase persormance marginally by going to a fatter case (and reducing mag capacity) but you cannot duplicate the performance of a full power cartridge in an assault rifle sized case.

Further, recoil is a huge factor in auto weapons. You need to keep recoil at or below that of the 7.62x39 AK. Other wise, you might as well go semi-automatic and use a full power case.

The current 5.56 fires a 62 bullet with a spec'd 3000fps in a 20" barrel. That can be beat, although when limited to ball ammo, lethality with a larger cartridge is an issue. The 223, at optimal ranges, tumbles and breaks up, giving it a huge advantage in wounding over other cartridges such as the various 7.62.

Here's what I would look for in a combat cartridge.

A bullet in the 80-110gn range with a velocity between 2500-2800 and a high BC. This will equal or better the energy of the 5.56. High BC, allowing the round to retain high energy at long range, making it suitabel for DMR and GPMG

Shoulder angle of between 20 and 25 degrees. Body taper of not less than 30 minutes of angle, and ideally about 1 degree.

Case head of 0.452 or less, otherwise just use a full power case.

Lose the requirement of M16 magazine size, but keep the overall length to less tha 2.600 inches and case length of less than 50mm.

The best bullet possibilities look to be 6mm, 6.5mm and 7mm as these have a number of suitible High BC bullets in the right weight range. A BC of over 0.400 is highly desireable. Over 0.500 is outstanding.

For developmental purposes, it is probably easiest to stick with standard case head size: 0.387, 0.422, 0.453.

Tod

dodging230grainers
August 1, 2007, 12:47 PM
I don't think there can be an "ultimate" combat round because it depends on what kind of people you're fighting.

If you're on the U.S. military side fighting completely unarmored insurgents with ****ty medical care, the 5.56mm NATO cartridge fits the bill perfectly. However, if we were fighting a modern army in WW2 style fighting, we might find the 5.56mm becomes much less effective due to increased ranges and the fact our enemy would have body armor similar to ours. Don't forget they'd have vehicles too.

From the insurgent point of view, the 5.56mm NATO might not be as effective against their enemies- U.S. soldiers. Our troops wear some of the most modern body armor to date, and we have some of the best medical care in the world.
Our troops are often behind cover, or inside a vehicle, meaning the insurgents are going to need a more powerful rifle cartridge to do the job.

So in short, the ultimate rifle combat round is the one that fits the job at the time. For us, right now, with the people we're currently fighting, I think the 5.56mm NATO does fine.

Nolo
August 1, 2007, 01:19 PM
In my first post I stated that there was really no such think as an "ultimate combat round", but I went ahead anyway. I think that, for an assault rifle, 6mm bullets are the best. They have extremely high ballistic coefficients (sometimes as high as .55) and have decent weight to them (80-120 grains). If you fitted that bullet with a case that had it doing around 3000 f/s and still was under 70mm (total cartridge length), you'd be golden. I think that could be accomplished by opening up the 5.45x39mm case (to 6mm) and lengthening it until you got acceptable pressures.

Nolo
August 1, 2007, 01:25 PM
Hey GunTech, could you run what velocities you'd get out of a 5.45x39mm case necked up to 6mm (100 grain bullet) through your doohickey?

GunTech
August 1, 2007, 08:14 PM
Here's you 5.45x39mm necked up to 0.243 with no other changes. BL-C(2) looks like one of the better powders.

Cartridge : 6 mm x 39 Nolo
Bullet : .243, 100, Sierra SPBT 1560
Cartridge O.A.L. L6: 2.244 inch or 57.00 mm
Barrel Length : 18.0 inch or 457.2 mm
Powder : Hodgdon BL-C2

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.735% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-07.4 90 22.24 2190 1065 37271 7804 91.5 1.187
-06.6 91 22.41 2209 1083 38189 7879 91.9 1.173
-05.9 92 22.59 2227 1102 39138 7952 92.3 1.160
-05.1 93 22.76 2246 1120 40110 8025 92.7 1.147
-04.4 93 22.94 2265 1139 41108 8097 93.1 1.134
-03.7 94 23.12 2283 1158 42135 8167 93.5 1.121
-02.9 95 23.29 2302 1177 43191 8236 93.9 1.109
-02.2 95 23.47 2321 1196 44276 8304 94.2 1.096
-01.5 96 23.65 2340 1216 45392 8370 94.6 1.084
-00.7 97 23.82 2358 1235 46540 8435 94.9 1.072
+00.0 98 24.00 2377 1255 47722 8499 95.2 1.060 ! Near Maximum !
+00.7 98 24.18 2396 1275 48939 8561 95.5 1.048 ! Near Maximum !
+01.5 99 24.35 2415 1295 50188 8622 95.8 1.037 ! Near Maximum !
+02.2 100 24.53 2434 1315 51477 8681 96.1 1.025 ! Near Maximum !
+02.9 100 24.71 2453 1336 52804 8738 96.4 1.014 ! Near Maximum !
+03.7 101 24.88 2472 1356 54169 8794 96.7 1.003 ! Near Maximum !

Nolo
August 1, 2007, 08:18 PM
That's all I get, huh? 1300 ft-lbs? Hmmm... How much longer would I have to make the case to get 2000 ft-lbs?

GunTech
August 1, 2007, 08:32 PM
My cartridge isn't doing much better:

http://guntech.com/ammo/6.5cmbt.jpg

At least it has a 40 minute of angle body taper and 23 degree shoulder


Cartridge : 6.5 combat
Bullet : .264, 108, Lapua Scenar GB464
Cartridge O.A.L. L6: 2.571 inch or 65.30 mm
Barrel Length : 20.0 inch or 508.0 mm
Powder : Winchester 760

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.735% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-07.4 91 34.28 2419 1403 35453 8526 84.8 1.239
-06.6 92 34.55 2440 1428 36302 8621 85.3 1.227
-05.9 93 34.82 2461 1453 37173 8716 85.8 1.215
-05.1 93 35.10 2483 1478 38067 8810 86.3 1.200
-04.4 94 35.37 2504 1504 38983 8903 86.8 1.187
-03.7 95 35.64 2525 1529 39924 8995 87.3 1.174
-02.9 95 35.91 2547 1555 40890 9086 87.7 1.161
-02.2 96 36.18 2568 1582 41883 9176 88.2 1.148
-01.5 97 36.46 2590 1608 42903 9265 88.7 1.135
-00.7 98 36.73 2612 1635 43948 9354 89.1 1.122 ! Near Maximum !
+00.0 98 37.00 2633 1663 45024 9440 89.6 1.110 ! Near Maximum !
+00.7 99 37.27 2655 1690 46126 9526 90.0 1.098 ! Near Maximum !
+01.5 100 37.54 2677 1718 47264 9610 90.5 1.085 ! Near Maximum !
+02.2 100 37.82 2698 1746 48431 9693 90.9 1.073 ! Near Maximum !
+02.9 101 38.09 2720 1774 49631 9774 91.3 1.062 ! Near Maximum !
+03.7 102 38.36 2742 1803 50864 9855 91.7 1.050 !DANGEROUS LOAD-DO NOT USE!

Nolo
August 1, 2007, 08:57 PM
I should be getting better performance out of this.
How long of a case do you need to propel the 6mm 100 grain bullet to 3000 f/s using a 5.45 case (lengthened, of course)?

timmyb21
August 1, 2007, 09:02 PM
6.8 spc, good comprimise between 5.56 and 7.62, already commercially available. (disclaimer: this is just my opinion, I have no professional experience with the round, but it would be cheap to convert the current issued 5.56 weapons to 6.8)

Nolo
August 1, 2007, 09:11 PM
That's not exactly the point of this, thread, however.
I know 6.8 is a good round, what I'm looking for is a round that doesn't have stupid constraints put on it by 30-year-old pieces of weaponry. I want the best.

GunTech
August 1, 2007, 09:24 PM
I already shoot 6.8. It is OK, as is 6.5 gredel, but you can only do so much when your constraint is that it has to fit in a M16 magazine. 6.8 is dtrictly a short range cartridge.

Whay I;d like to see is something suitable for an assault rifle, that can also function well in a DMR or GPMG. 6.5 gre.del actually has more energy at long range than 308 thanks to a high BC bullet. But the gredel has almost no body taper and a steep shoulder, making it less than ideal in auto weapons.

My own idea was to lengthen and taper the 6.5 grendel to optimize it for auto weapons. Target velocity with the 108 gn Lapua scenar is 2800 fps.

Nolo
August 1, 2007, 09:31 PM
GunTech, how long does a 5.45 case have to be to push the 6mm 100gr. bullet 3000 f/s?

Oh, and a new, improved 6x49mm round:

http://i200.photobucket.com/albums/aa149/Nolo_photo/6x49mmImproved.gif

Base Diameter: .414 inches or 10.523mm
Length of Case Under Shoulder: 1.529 inches or 38.838mm
Length of Case Under Neck: 1.683 inches or 42.736mm
Length of Case Overall: 1.963 inches or 49.860mm
Shoulder Angle: 30 degrees
Diameter of Case Opening: .267 inches or 6.782mm
Weight of Projectile: 100 or 110 grains

jerkface11
August 1, 2007, 09:51 PM
.250 savage is big now?? Ever seen a loaded round?Hardly a large cartridge.It gets 300fps easily without high pressures. Of course it won't fit in an m16 mag but so what?The sexy military designation would be 6.65x48.

GunTech
August 1, 2007, 10:26 PM
I finally did it. I reached my goal of 2800 fps with a 108 gn 6.5 lapua scenar at about 49,000psi. Case has a 45 minute taper and a 23 degree shoulder for optimal feeding.

6.5x48

http://guntech.com/ammo/6.5x48.jpg

The 6.5x48 is based on a lengthed 7.62x39, and makes 2800 fps with moderate pressure - well under 6.5 Grendel. In a strong action, it could make 3000 fps at 260 Rem pressures.

Cartridge : 6.5x48
Bullet : .264, 108, Lapua Scenar GB464
Cartridge O.A.L. L6: 2.625 inch or 66.68 mm
Barrel Length : 24.0 inch or 610.0 mm
Powder : IMR 4895

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.735% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-07.4 90 30.39 2609 1632 39310 6856 96.7 1.299
-06.6 91 30.63 2628 1657 40179 6906 97.0 1.286
-05.9 92 30.87 2648 1681 41069 6955 97.2 1.273
-05.1 93 31.11 2667 1706 41978 7002 97.5 1.261
-04.4 93 31.35 2686 1730 42908 7048 97.7 1.248
-03.7 94 31.59 2705 1755 43856 7093 98.0 1.236
-02.9 95 31.84 2725 1780 44832 7136 98.2 1.224
-02.2 95 32.08 2744 1805 45826 7178 98.4 1.212
-01.5 96 32.32 2763 1830 46845 7218 98.6 1.201
-00.7 97 32.56 2782 1856 47886 7257 98.7 1.189
+00.0 98 32.80 2801 1881 48952 7294 98.9 1.178
+00.7 98 33.04 2820 1907 50041 7330 99.1 1.166 ! Near Maximum !
+01.5 99 33.28 2839 1933 51156 7364 99.2 1.155 ! Near Maximum !
+02.2 100 33.52 2858 1958 52298 7396 99.3 1.144 ! Near Maximum !
+02.9 100 33.76 2877 1984 53467 7427 99.5 1.133 ! Near Maximum !
+03.7 101 34.01 2895 2010 54663 7456 99.6 1.122 ! Near Maximum !

GunTech
August 1, 2007, 10:41 PM
Starting with a 7.62x39 case head (0.452 same as 5.45) you have to blow out and lengthen the case to about 51mm to make 3000 with a 90gn 243 bullet without going ionto the realm of extreme pressure.

GunTech
August 1, 2007, 11:06 PM
Oh, and a new, improved 6x49mm round:

http://i200.photobucket.com/albums/aa149/Nolo_photo/6x49mmImproved.gif

Base Diameter: .414 inches or 10.523mm
Length of Case Under Shoulder: 1.529 inches or 38.838mm
Length of Case Under Neck: 1.683 inches or 42.736mm
Length of Case Overall: 1.963 inches or 49.860mm
Shoulder Angle: 30 degrees
Diameter of Case Opening: .267 inches or 6.782mm
Weight of Projectile: 100 or 110 grains



Cartridge : 6x49
Bullet : .243, 100, Lapua MEGA E457
Cartridge O.A.L. L6: 2.635 inch or 66.93 mm
Barrel Length : 20.0 inch or 508.0 mm
Powder : Hodgdon H4350

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.735% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-07.4 90 31.96 2462 1346 38120 10344 92.1 1.243
-06.6 91 32.22 2482 1368 39018 10445 92.6 1.230
-05.9 91 32.47 2503 1391 39928 10545 93.0 1.216
-05.1 92 32.72 2524 1414 40859 10643 93.4 1.203
-04.4 93 32.98 2544 1437 41811 10739 93.8 1.190
-03.7 93 33.23 2565 1461 42794 10834 94.2 1.177
-02.9 94 33.49 2586 1484 43795 10927 94.5 1.164
-02.2 95 33.74 2606 1508 44823 11018 94.9 1.152
-01.5 95 33.99 2627 1532 45877 11108 95.2 1.139
-00.7 96 34.25 2648 1557 46959 11195 95.6 1.127
+00.0 97 34.50 2669 1581 48066 11280 95.9 1.115
+00.7 98 34.75 2689 1606 49202 11364 96.2 1.103
+01.5 98 35.01 2710 1631 50368 11445 96.5 1.091 ! Near Maximum !
+02.2 99 35.26 2731 1656 51562 11524 96.8 1.079 ! Near Maximum !
+02.9 100 35.51 2751 1681 52789 11601 97.1 1.067 ! Near Maximum !
+03.7 100 35.77 2772 1707 54047 11676 97.3 1.056 ! Near Maximum !

Tony Williams
August 2, 2007, 01:53 AM
I posted my analysis of the assault rifle round issue here: http://www.quarry.nildram.co.uk/Assault.htm

This is an extract from it:

Such an "ideal" cartridge would need to combine a long-range effectiveness comparable with the 7.62mm, with a recoil light enough to permit controlled, full-auto fire. Is it possible to achieve this? The evidence suggests strongly that it is. The British aimed to do this with the 7x43 cartridge half a century ago, and by all accounts succeeded admirably. This gives us an upper calibre limit. I don't think that a useful increase in performance over the 5.56mm can be achieved with anything smaller than 6mm calibre, which gives us the lower limit. We need to specify a bullet sectional density ratio of about .230 in order to retain velocity better than the 7.62mm (whose 9.33g bullet has an SDR of 0.217 - the 5.56mm SS109 bullet has an SDR of 0.174,and the new 5.0g Mk 262 is 0.220) and thereby deliver the long-range performance we want. We also need a muzzle energy of no more than 2,500 joules to provide the right balance of power and recoil. Taking into account that smaller calibres need less energy to penetrate armour, this works out as the following range of choices in common calibres:

7mm/.276": bullet weight 8.4g (130 grains) at 770 m/s (2,525 fps) = 2,500j

6.85mm/.270": bullet weight 7.9g (122 grains) at 784 m/s (2,570 fps) = 2,430j

6.5mm/.258": bullet weight 6.9g (106 grains) at 820 m/s (2,690 fps) = 2,330j

6.35mm/.25": bullet weight 6.5g (100 grains) at 834 m/s (2,736 fps) = 2,260j

6mm/.24": bullet weight 5.9g (91 grains) at 854 m/s (2,800 fps) = 2,150j

Any of the above options would do, but for the sake of argument let's take the 6.5mm. A cartridge of this calibre would be smaller than the more powerful 6.5mm Arisaka. If a similar case diameter were retained then length could be reduced to about 45mm. In fact, the case diameter and length would be similar for all of the above cartridges.

These rounds - especially at the larger calibre end - are pushing the maximum recoil for controllability in auto fire, so stepping up the power by any significant amount will limit you to semi-auto only.

On the problem of piercing body armour, raised earlier by 'Don't Tread On Me', these can be addressed by improving the bullets - tungsten-cored 5.56mm and 7.62mm AP ammo is available already, and APDS could be used if required. It's worth noting that the Russians have been ramping up the AP performance of the 5.45mm with better penetrating cores, including tungsten carbide.

Nolo
August 2, 2007, 09:44 AM
Hehehe...
I read your stuff all the time.
:)
Good stuff.
I'm still flabbergasted at why I can't get the velocities that I want out of my 6mm. I don't get it. Basically, my maximum velocity (for an assault rifle) is 2700. I want to add about 300 f/s to that, but I'm definitely hitting the ceiling of how big my cartridge can be. If I go any larger, my velocity will get higher, but my EPP will pretty much stay stagnant or, even worse, go lower. As is, I've only got an EPP of about 48000, which is lower than that of any of the other calibers that I've calculated before. :cuss: :banghead: :cuss: :banghead: So we might as well use .223 as my 6mm, because you get no weight benefits from it. This is what I'm trying to defeat. Let me check your cartridge, GunTech. How much does it weigh? And I like your cartridge, but the weight of the bullet seems too light (for a 6.5mm) to me, and the cartridge too big. Still good, though.
Oh, and what are you using to generate those images? I want one.

Nolo
August 2, 2007, 09:47 AM
BLARG!!!!!
Why can't I get the velocities that I want out of a 6mm cartridge of acceptable size with a 10mm (or smaller) base!?!?!?!?!?!
:banghead::banghead::banghead::banghead::banghead::banghead::banghead::banghead::banghead::banghead::banghead::banghead::banghead::banghead::banghead::banghead::banghead::banghead::banghead::banghead::banghead::banghead::banghead::banghead::banghead:

glockman19
August 2, 2007, 10:03 AM
+1 to everyting Nolo said.

JWarren
August 2, 2007, 10:11 AM
Interesting thread-- one that is a bit more technical than I can really contribute to.

I do have one question and one comment however.

Regarding "Gun hose"... Isn't this a SMG? SMG's are usually designated as a special purpose SMG or a general purpose SMG. This is mostly a funtion of their rate-of-fire respectively. SP-SMG's operate with significantly higher rates of fire than GP-SMGs. At any rate, I am just wondering why we are using the term "gun hose?"




So the Glock has seen service, it hasn't seen combat, as far as I'm aware. Plus, we haven't really seen the true test of plastics: the test of time. Will they wear out? Do they create structural problems later in life? Until I see that they are truly successful, I will stick to the good ole' mostly metal guns.


Nola, the are durable. I can understand if one doesn't LIKE Glocks, but they've proven to hold up. I've been daily carrying a Generation-II Glock 19 for literally 13 years. Same gun. It's been with me everywhere from deer hunting (as a side arm) in swamps to hanging on the beach at our condo. I won't say that I've never had a milfunction, but I honestly can't think of one. Anyway, I thought you'd like to have that in your assessment. I'm not trying to go "Fanboy" for Glocks-- but I think they've put down the concerns of holding up. That said, my 1911A1 comes in tomorrow. :)



--John

jerkface11
August 2, 2007, 10:24 AM
Why the desire to make the cartridge have a base diameter of 10mm or smaller? That is the ONLY criteria of yours that 6.65x48 does not meet. It even makes a 100 grain bullet go 3000 fps.

GunTech
August 2, 2007, 11:19 AM
Nolo,

The software I use for cartridge design and load analysis are called quickdesign and quickload, respectively. They are exceptionally useful to wildcatters and cartridge developers, but are really only a guide. You have to follow up with real world testing. In most cases, I find Quickload very accurate to real orld performance, but not always.

Each program costs $150, and runs on a PC running windows 98, XP or vista. I am actually running it on my mac under parallels.

Also note, I am calculating all velocities from a 20 inch barrel. Shorter or longer barrels will effect velocity. The industry standard is typically a 24 inch barrel, which can add as much as 200 fps to velocity, which may be why these numbers look low to many peopl. All of my calculations are based on conservative numbers: 20 inch barrel, low pressure, etc. You could easily get better performance using higher pressures and longer barrels, but this would not reflect current military rifles.

I'll post some more options on the 6.5x58. The cartridge came out big because I kept the shoulder angle under 25 degrees and doubles the body taper of the 5.56x45. If you adopt small body taper and sharp shoulder, you can get a shorter case, but at the expense of reliability.

QuickLoad and QuickDesign are available here:

http://www.neconos.com/

PercyShelley
August 2, 2007, 11:38 AM
I know that we're not considering the weapons platform for these cartridges, but taking a more holistic look for just a moment, what about a short, fat cartridge with no body taper at all?

Consider the FN P90; the cases have a special polymer coating to ensure reliable feeding despite the lack of taper. Since the cases are straight, they maximise volume, although nobody would hold up the 5.7 as a ballistic majesty by any means.

Suppose that we sink the bullet fully into such a case in the manner of the Nagant gas-sealed revolver round, except with as short as possible a neck and extend the shoulder out to reclaim lost powder space. The shoulder could be made rather sharp without causing feeding difficulties, since there will be no bullet to catch on. This arrangement may necessitate the use of sabots to give the neck something to grab near the front of the bullet.

If we keep the cartridge to a reasonable OAL, we can use a P90 horizontal feed, which on an assault rifle could be quite an asset. Since the magazine could be made very long compared to the magazine on the P90; we could have potentially half a meter to work with if the assault rifle is a bullpup, the cartridges could be made as fat as we want. In addition to being ballistically vogue right now, I suspect that they will be lighter, since geometry alone would suggest that a short fat cylinder of equal volume to a long skinny one will have less surface area, and thus less brass weight.

Nolo
August 2, 2007, 12:47 PM
Thank you all.
I've really honed what I want to do with "my" assault rifle here. I want to send a 6mm (100 grain) bullet 3000 f/s with a better than 55000 EPP. Hard, but I think I can do it as long as I work long enough on it. And I realize that only the real-world test is enough, hence my assessment of "plastic guns". I have absolutely nothing against these guns, but reliability is key, and I don't want to trust the structural integrity of my weapon to plastic... yet.
As for the service that your Glock has seen, have you ever gone into combat with it (this is an actual question, it's quite possible that you have), and, if so, how has it performed? Being in a holster all day is very different from being in the sandbox. Even the most reliable shotguns (for instance) in the civilian market seem unreliable when shoved into military combat. It is truly a different world. Also, for GunTech, I would not put too much into reliability of feeding, while that is highly important to a weapon like the M16, if you mate an "unreliable" cartridge with a reliable rifle, your shouldn't have a problem.

Now, let me explain the "gun hose" concept. You may be asking, why in the world doesn't he just call it a submachine gun? Well, because it's not a submachine gun. Subbies shoot pistol ammunition, a "gun hose", as I conceive it, shoots miniature (very miniature, as small as 4mm) rifle ammunition. Also, subbies tend to (not always, look at the 10-pound Thompson) weigh less than assault rifles, whereas "gun hoses" weigh the same as assault rifles, up to 10 pounds. Also, submachine guns generally use 30- or 50- round box magazines, a "gun hose" uses 75- or 100-round magazines (drum or otherwise), and, depending on the gun, sometimes as much as 200-round magazines. Thus, for a "gun hose", weight of the ammunition is key. It must be small, or else the poor soldier carrying the weapon will be overburdened. Also, "gun hoses" must not only have high rates of fire, they must have extreme rates of fire, preferrably in the 2000 rpm range. When your round only produces 300 ft-lbs of energy or less, you'd better be dishing those puppies out at high rates of fire. Also, burst settings for "gun hoses" should be as large as 7-10 rounds per burst, or else your effectiveness is moot over an assault rifle. Also, "gun hoses" need to be accurate, so that you don't lose any of that effectiveness. So that's a "gun hose", and the differences between it and a submachine gun. Oh, and if anyone can think of a better name for the "gun hose" concept, please let me know.

Some pictures of the weapons that inspired the "gun hose" concept:

The American 180 submachine gun:
http://i200.photobucket.com/albums/aa149/Nolo_photo/am180-1.jpg
Caliber: .22 ILARCO proprietary ammunition
Magazine Capacity: Up to 275 rounds
Rate of Fire: 1500 rounds per minute

The Fabrique Nationale P90 PDW:
http://i200.photobucket.com/albums/aa149/Nolo_photo/fn_p90_2.jpg
Caliber: 5.7x28mm proprietary ammunition
Magazine Capacity: 50 rounds
Rate of Fire: 900 rounds per minute

Nolo
August 2, 2007, 12:51 PM
Percy Shelley, in my first post, I said that we weren't considering platforms unless it directly pertained to the choice of round. Which is exactly what you are doing. You idea is excellent. I appreciate the input of thought, it's exactly what I'm here for.

Excellent input. I'll look into that idea. It also makes the round light, which adds to the EPP (see my earlier post).

Nolo
August 2, 2007, 12:54 PM
Jerkface, I want the cartridge to be smaller than 10mm because of the fact that anything larger comes close to a battle rifle case, and weight is highly important. Any modern combat weapon should have an EPP of above 50000, ideally above 55000, and, in my dreams, 60000 or higher.

GunTech
August 2, 2007, 01:02 PM
Nolo, here's a new 6.5 round, based on a 6.5 Grendel. lengthened to 45mm, hence 6.5x45. It has less body taper than the previous cartridge, and a sharper shoulder. I increase body taper so that it is still more than 5.56x45.

http://guntech.com/ammo/6.5x45.jpg

Here's a comparison to 308

http://guntech.com/ammo/6.5vs308.jpg

Loading data:

With 108gn 6.5mm Lapua Scenar (BC 0.478) from a 20 inch barrel


Cartridge : 6.5x45
Bullet : .264, 108, Lapua Scenar GB464
Cartridge O.A.L. L6: 2.507 inch or 63.68 mm
Barrel Length : 20.0 inch or 508.0 mm
Powder : Winchester 748

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.735% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-07.4 84 30.39 2502 1501 39757 8210 95.9 1.176
-06.6 85 30.63 2521 1525 40682 8274 96.2 1.164
-05.9 86 30.87 2541 1548 41628 8336 96.5 1.152
-05.1 86 31.11 2560 1572 42598 8397 96.8 1.140
-04.4 87 31.35 2579 1595 43588 8457 97.0 1.128
-03.7 88 31.59 2599 1619 44607 8515 97.3 1.116
-02.9 88 31.84 2618 1643 45648 8571 97.5 1.105
-02.2 89 32.08 2637 1668 46717 8626 97.8 1.093
-01.5 90 32.32 2656 1692 47811 8679 98.0 1.082
-00.7 90 32.56 2675 1717 48932 8730 98.2 1.071
+00.0 91 32.80 2695 1741 50081 8780 98.4 1.060 ! Near Maximum !
+00.7 92 33.04 2714 1766 51259 8827 98.6 1.049 ! Near Maximum !
+01.5 93 33.28 2733 1791 52467 8873 98.8 1.038 ! Near Maximum !
+02.2 93 33.52 2752 1816 53704 8918 98.9 1.028 ! Near Maximum !
+02.9 94 33.76 2771 1841 54970 8960 99.1 1.017 ! Near Maximum !
+03.7 95 34.01 2790 1866 56274 9000 99.2 1.007 ! Near Maximum !


With a 123gn Lapua Scenar (BC 0.547)


Cartridge : 6.5x45
Bullet : .264, 123, Lapua Scenar GB489
Cartridge O.A.L. L6: 2.507 inch or 63.68 mm
Barrel Length : 20.0 inch or 508.0 mm
Powder : IMR 4895

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.735% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-07.4 89 28.72 2355 1514 39680 8132 96.8 1.233
-06.6 89 28.95 2372 1537 40540 8194 97.1 1.221
-05.9 90 29.18 2390 1560 41424 8255 97.3 1.209
-05.1 91 29.40 2408 1583 42325 8314 97.6 1.197
-04.4 92 29.63 2425 1606 43245 8371 97.8 1.185
-03.7 92 29.86 2443 1629 44185 8427 98.0 1.173
-02.9 93 30.09 2460 1653 45145 8482 98.2 1.162
-02.2 94 30.32 2478 1676 46127 8535 98.4 1.150
-01.5 94 30.54 2495 1700 47131 8586 98.6 1.139
-00.7 95 30.77 2512 1724 48156 8635 98.8 1.128
+00.0 96 31.00 2530 1748 49206 8682 99.0 1.117
+00.7 97 31.23 2547 1772 50279 8728 99.1 1.106 ! Near Maximum !
+01.5 97 31.46 2564 1796 51375 8772 99.2 1.095 ! Near Maximum !
+02.2 98 31.68 2582 1820 52496 8815 99.4 1.085 ! Near Maximum !
+02.9 99 31.91 2599 1845 53642 8855 99.5 1.075 ! Near Maximum !
+03.7 99 32.14 2616 1869 54816 8893 99.6 1.064 ! Near Maximum !


With a 139gn Lapua Scenar (BC 0.615)


Cartridge : 6.5x45
Bullet : .264, 139, Lapua Scenar GB458
Cartridge O.A.L. L6: 2.507 inch or 63.68 mm
Barrel Length : 20.0 inch or 508.0 mm
Powder : Winchester 760

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.735% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-07.4 91 31.69 2248 1560 40439 8631 91.4 1.302
-06.6 92 31.94 2267 1586 41419 8712 91.8 1.288
-05.9 93 32.19 2286 1613 42425 8792 92.2 1.273
-05.1 94 32.44 2305 1639 43457 8871 92.6 1.259
-04.4 94 32.69 2324 1666 44514 8949 93.0 1.245
-03.7 95 32.94 2342 1694 45601 9026 93.3 1.231
-02.9 96 33.19 2361 1721 46717 9101 93.7 1.218
-02.2 97 33.45 2380 1749 47863 9174 94.1 1.205
-01.5 97 33.70 2399 1777 49039 9247 94.4 1.191
-00.7 98 33.95 2418 1805 50249 9317 94.7 1.178 ! Near Maximum !
+00.0 99 34.20 2437 1833 51486 9386 95.1 1.166 ! Near Maximum !
+00.7 99 34.45 2456 1862 52765 9454 95.4 1.153 ! Near Maximum !
+01.5 100 34.70 2475 1891 54076 9520 95.7 1.140 ! Near Maximum !
+02.2 101 34.95 2494 1920 55424 9584 96.0 1.128 ! Near Maximum !
+02.9 102 35.21 2513 1949 56810 9646 96.3 1.115 ! Near Maximum !
+03.7 102 35.46 2532 1979 58234 9707 96.6 1.103 !DANGEROUS LOAD-DO NOT USE!




Ballistics:

Velocity

M855 3000 2721 2458 2210 1977 1760 1561 1384 1236 1121 1037
108 2695 2529 2369 2214 2065 1923 1786 1657 1536 1424 1323
123 2530 2390 2254 2122 1995 1873 1755 1644 1538 1440 1349
139 2437 2315 2196 2080 1968 1860 1756 1656 1561 1472 1388
M80 2700 2498 2306 2121 1946 1780 1624 1481 1352 1240 1148


Energy

M855 1239 1019 832 673 538 426 335 264 210 173 148
108 1742 1533 1345 1176 1023 886 765 659 566 486 419
123 1748 1559 1387 1230 1087 958 841 738 646 566 497
139 1833 1653 1488 1335 1195 1068 952 847 752 669 595
M80 2412 2065 1759 1489 1253 1048 873 725 605 509 436


Recoil of round in a 9 pound rifle (M43 7,62x39mm included)

Bullet Impulse Free Velocity Free Energy
M855 1.3 lbs-sec 4.5 fps 2.9 ft-lbs
108 1.4 4.9 3.4
123 1.9 7.6 6.8
139 2.1 7.4 7.7
M43 1.9 6.8 6.4
M80 2.5 8.9 11.1


Please note the 6.5x45mm veolities are very conservative copmpared to 6.5 Grendel.

Nolo
August 2, 2007, 01:12 PM
That seems really good for a mid-range (AK-sized) rifle. For a smaller rifle, I'd like something in 6mm. What do you get if you neck that down to 6mm?

Oh, and, if you expand the case of the 6mm Firebrand to the same case diameter as the 6.8 Remington SPC, what do we get out of it?

Nolo
August 2, 2007, 01:17 PM
By the way, I think you've just cracked the mid range weapon here.
Let me calculate the EPP for it.
The EPP for that cartridge (6.5x45mm) is only 50000. :fire: How much does it weigh, approximately? Can you figure that out?

Nolo
August 2, 2007, 01:20 PM
HEY GUYS!
I'M A SENIOR MEMBER!
I feel so old...

GunTech
August 2, 2007, 01:33 PM
I looked at the figures for the 6.5 Grendel, and they show 2700 fps for the 108 lapua scenar. To get that, they use a 24 inch barrel and a chamber pressure or around 52,000psi (calculated). Loading the 6.5x45 to the same pressure, that gives 2875fps in a 24 inch barrel, and 2825fps in 20 inches, 175fps faster than I originally calculated. Let me run the new numbers.

I think recoil will be a bit high - not up in 308 land, but more than an AK-47. Ballistic should beat the 308 at 400 yards or so, and weigh about 2/3s

Nolo, I'll work up a 6mm, but with a 100 gn bullet, performace should be similar. I think you are looking at around 2850fps from a 20 inch barrel, which is rocking!

Nolo
August 2, 2007, 01:52 PM
If your cartridge weighs 2/3s of a .308, then you get over 55000 EPP, which is right on target.
Similar for a 6mm, but a higher ballistic coefficient? Sounds good. Can you run my widened 6mm (to SPC base) through your doohickey?
By the way, if we choose the right rifle, recoil is essentially a non-issue.

Nolo
August 2, 2007, 01:56 PM
Oh, and GunTech, can you keep that performance and thin up or taper you case?

Tony Williams
August 2, 2007, 02:50 PM
By the way, if we choose the right rifle, recoil is essentially a non-issue.

Well, true enough if you only want semi-auto fire - or if the 'right rifle' weighs 20 lbs!

GunTech
August 2, 2007, 03:13 PM
I set the rifle weight at 9 pounds, AK weight, or an M16 with all the doodads. 9 Pound seems to be pretty typical for a military rifle. I didn't factor in a muzzle brake, which is becoming standard on Russian weapons. A suppressor would be even better, since it works as a recoil reducer as well as keeping sound and flash to manageable levels.

NOLO,

I'll post more data later this afternoon once I get done with some chores.

Nolo
August 2, 2007, 05:28 PM
Yes, Tony Williams, recoil can be a non-issue if we choose the right weapon. In otherwords, a weapon that either uses constant recoil, the laterally moving breechblock system or a balanced action.

GunTech
August 2, 2007, 11:52 PM
Here's the updated data for 6.5x45mm using 6.5 Grendel pressures

Velocity:


Bullet 0 100 200 300 400 500 600 700 800 900 1000
M855 3000 2721 2458 2210 1977 1760 1561 1384 1236 1121 1037
108 2824 2753 2488 2329 2176 2029 1888 1754 1626 1507 1398
123 2650 2506 2366 2231 2100 1974 1852 1736 1625 1521 1424
139 2514 2389 2268 2151 2036 1926 1819 1717 1619 1526 1439
M80 2700 2498 2306 2121 1946 1780 1624 1481 1352 1240 1148


Energy:

M855 1239 1019 832 673 538 426 335 264 210 173 148
108 1912 1688 1485 1301 1136 987 855 737 634 545 469
123 1918 1715 1529 1359 1205 1064 937 823 721 632 554
139 1951 1762 1588 1427 1280 1145 1022 910 809 719 639
M80 2412 2065 1759 1489 1253 1048 873 725 605 509 436


Recoil

Bullet Impulse Free Velocity Free Energy
M855 1.3 lbs-sec 4.5 fps 2.9 ft-lbs
108 1.9 6.9 6.6
123 2 7.2 7.3
139 2.1 7.6 8
M43 1.9 6.8 6.4
M80 2.5 8.9 11.1


The 108gn Lapua Scenar at 2825 is a pretty substantial round. Bear in mind that the velocity shown is from a 20 inch barrel.

The 108 6.5x45mm betters the velocity of M80 7.62x31 at all ranges. At 600 yards, the 6.5 passed the 308 in energy, and yet has about half the recoil (Close to the AK-47 M43) with a cartridge about 2/3 the size.

GunTech
August 3, 2007, 12:03 AM
Nolo,

Here's the 6x45 Nolo, the 6.5x45 necked down to 0.243 with no other changes


Cartridge : 6x45 Nolo
Bullet : .243, 100, Lapua MEGA E457
Cartridge O.A.L. L6: 2.507 inch or 63.67 mm
Barrel Length : 20.0 inch or 508.0 mm
Powder : Hodgdon H4350

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.735% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-07.4 89 32.89 2512 1401 38032 10819 92.0 1.236
-06.6 90 33.15 2533 1424 38908 10927 92.4 1.222
-05.9 91 33.41 2554 1448 39806 11033 92.8 1.209
-05.1 92 33.67 2575 1472 40726 11138 93.2 1.196
-04.4 92 33.93 2596 1496 41669 11242 93.6 1.182
-03.7 93 34.19 2617 1521 42632 11343 94.0 1.170
-02.9 94 34.46 2638 1546 43622 11443 94.4 1.157
-02.2 94 34.72 2660 1571 44637 11541 94.7 1.144
-01.5 95 34.98 2681 1596 45676 11638 95.1 1.132
-00.7 96 35.24 2702 1621 46741 11732 95.4 1.120
+00.0 97 35.50 2723 1647 47831 11824 95.7 1.107
+00.7 97 35.76 2745 1673 48951 11915 96.0 1.096
+01.5 98 36.02 2766 1699 50094 12003 96.4 1.084 ! Near Maximum !
+02.2 99 36.28 2787 1725 51274 12089 96.6 1.072 ! Near Maximum !
+02.9 99 36.54 2809 1752 52481 12173 96.9 1.061 ! Near Maximum !
+03.7 100 36.81 2830 1778 53719 12255 97.2 1.049 ! Near Maximum !

chemist308
August 3, 2007, 12:05 AM
How is it more folks are not saying 243 Winchester?! It fits most of the original poster's requirements prefectly!

And if AR-10s and M14s take the 308, why could the original M-16 have been designed to take the 243?

GunTech
August 3, 2007, 12:22 AM
I randthe numbers with a bullet with higher BC. the Lapua Scenar 105 with a BC of 0.540. Muzzel velocity at 6.5 Grendel pressure is 2707 fps. Here's how it stacks up against other catridges already shown.

Velocity

Bullet 0 100 200 300 400 500 600 700 800 900 1000
M855 3000 2721 2458 2210 1977 1760 1561 1384 1236 1121 1037
6 105 2707 2559 2416 2278 2144 2014 1889 1770 1656 1548 1448
6.5 108 2824 2753 2488 2329 2176 2029 1888 1754 1626 1507 1398
6.5 123 2650 2506 2366 2231 2100 1974 1852 1736 1625 1521 1424
6.5 139 2514 2389 2268 2151 2036 1926 1819 1717 1619 1526 1439
M80 2700 2498 2306 2121 1946 1780 1624 1481 1352 1240 1148


Energy:

M855 1239 1019 832 673 538 426 335 264 210 173 148
6 105 1741 1556 1387 1232 1092 964 848 744 652 570 498
6.5 108 1912 1688 1485 1301 1136 987 855 737 634 545 469
6.5 123 1918 1715 1529 1359 1205 1064 937 823 721 632 554
6.5 139 1951 1762 1588 1427 1280 1145 1022 910 809 719 639
M80 2412 2065 1759 1489 1253 1048 873 725 605 509 436


Recoil:

Bullet Impulse Free Velocity Free Energy
M855 1.3 lbs-sec 4.5 fps 2.9 ft-lbs
6 105 1.9 6.8 6.5
6.5 108 1.9 6.9 6.6
6.5 123 2 7.2 7.3
6.5 139 2.1 7.6 8
M43 1.9 6.8 6.4
M80 2.5 8.9 11.1

GunTech
August 3, 2007, 12:29 AM
243 Winchester doesn't buy you much. The case is quite a bit bigger - 6mm longer and with a case head size of 0.473. It's about 50% bigger, and at the same pressure only gives you and extra 28 fps. It requires a much larger action. Why bother for a military rifle?

243 using the same 105 gn Lapua scenar. Note the velocity around 52,000 psi - only about 2735 fps compared with the 6x45 Nolo at 2707.


Cartridge : .243 Win.
Bullet : .243, 105, Lapua HPBT Scenar GB478
Cartridge O.A.L. L6: 2.710 inch or 68.83 mm
Barrel Length : 20.0 inch or 508.0 mm
Powder : Hodgdon H4350

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.735% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-07.4 84 36.78 2557 1524 42065 11891 96.8 1.255
-06.6 85 37.07 2577 1548 43030 11985 97.1 1.241
-05.9 86 37.36 2597 1572 44018 12076 97.4 1.228
-05.1 86 37.66 2616 1596 45029 12166 97.6 1.215
-04.4 87 37.95 2636 1620 46064 12253 97.9 1.202
-03.7 88 38.24 2656 1645 47113 12337 98.1 1.190
-02.9 88 38.53 2676 1669 48206 12419 98.3 1.177
-02.2 89 38.82 2695 1694 49314 12499 98.5 1.165
-01.5 90 39.12 2715 1719 50447 12576 98.7 1.152
-00.7 90 39.41 2735 1744 51603 12651 98.9 1.141 ! Near Maximum !
+00.0 91 39.70 2754 1769 52781 12722 99.1 1.129 ! Near Maximum !
+00.7 92 39.99 2774 1794 53982 12791 99.2 1.117 ! Near Maximum !
+01.5 93 40.28 2794 1819 55209 12857 99.4 1.106 ! Near Maximum !
+02.2 93 40.58 2813 1845 56463 12921 99.5 1.094 ! Near Maximum !
+02.9 94 40.87 2832 1871 57745 12981 99.6 1.083 ! Near Maximum !
+03.7 95 41.16 2852 1896 59056 13039 99.7 1.072 ! Near Maximum !

GunTech
August 3, 2007, 12:31 AM
The 243 would have to use an AR-10 action. The M16 is sized fior a much shorter and smaller case. The upper limit the 7.62x39 or the 6.5 Grendel or similar sized case. The 243 requires the same sized action as the 308.

GunTech
August 3, 2007, 12:42 AM
I added 243 to the matrix, just for comparison. Note that the 243 uses about 5 grains of powder to gain 28 fps over the 6x45 Nolo. That extra powder also adds up to extra recoil. I still like the way the 6.5x45 looks compared to all others.

Velocity

Bullet 0 100 200 300 400 500 600 700 800 900 1000
M855 3000 2721 2458 2210 1977 1760 1561 1384 1236 1121 1037
6 105 2707 2559 2416 2278 2144 2014 1889 1770 1656 1548 1448
243 2735 2586 2442 2303 2168 2038 1912 1792 1677 1568 1466
6.5 108 2824 2753 2488 2329 2176 2029 1888 1754 1626 1507 1398
6.5 123 2650 2506 2366 2231 2100 1974 1852 1736 1625 1521 1424
6.5 139 2514 2389 2268 2151 2036 1926 1819 1717 1619 1526 1439
M80 2700 2498 2306 2121 1946 1780 1624 1481 1352 1240 1148


Energy

M855 1239 1019 832 673 538 426 335 264 210 173 148
6 105 1741 1556 1387 1232 1092 964 848 744 652 570 498
243 1777 1589 1417 1260 1117 987 869 763 668 584 511
6.5 108 1912 1688 1485 1301 1136 987 855 737 634 545 469
6.5 123 1918 1715 1529 1359 1205 1064 937 823 721 632 554
6.5 139 1951 1762 1588 1427 1280 1145 1022 910 809 719 639
M80 2412 2065 1759 1489 1253 1048 873 725 605 509 436


Recoil

Bullet Impulse Free Velocity Free Energy
M855 1.3 lbs-sec 4.5 fps 2.9 ft-lbs
6 105 1.9 6.8 6.5
243 2 7.2 7.2
6.5 108 1.9 6.9 6.6
6.5 123 2 7.2 7.3
6.5 139 2.1 7.6 8
M43 1.9 6.8 6.4
M80 2.5 8.9 11.1

GunTech
August 3, 2007, 12:47 AM
Here is a more limited view. 6x45 Nolo (105 gn Laupua Scenar) vs 243 (108 gn Laupua Scenar) vs 6.5x45 (105 gn Laupua Scenar).

Velocity:

Bullet 0 100 200 300 400 500 600 700 800 900 1000
6 105 2707 2559 2416 2278 2144 2014 1889 1770 1656 1548 1448
243 2735 2586 2442 2303 2168 2038 1912 1792 1677 1568 1466
6.5 108 2824 2753 2488 2329 2176 2029 1888 1754 1626 1507 1398


Energy

Bullet 0 100 200 300 400 500 600 700 800 900 1000
6 105 1741 1556 1387 1232 1092 964 848 744 652 570 498
243 1777 1589 1417 1260 1117 987 869 763 668 584 511
6.5 108 1912 1688 1485 1301 1136 987 855 737 634 545 469


Recoil

Bullet Impulse Free Velocity Free Energy
6 105 1.9 6.8 6.5
243 2 7.2 7.2
6.5 108 1.9 6.9 6.6


If one keeps in mind that 90% of all infantry small arms combat happens at 300 yards or less, 6.5x45mm looks pretty good. For DMR & Sniper applications, the 139 gn Scenar can be issued. This round adds recoil but performs better than the 6mms at long range.

FLORIDA KEVIN
August 3, 2007, 01:00 AM
This has been very interesting ! How about we lose the cartridge all togetherwe use a combustion chamber and an electrically ignited liquid fuel ,with a magazine full of projectiles ! Nothing to eject and a very short action as it only has to chamber a projectile !when you switch the selector to full auto ,it also turns down the metering on the fuel /propellant for lower velocity and recoil resulting in better controll ??!! What do you think ? Kevin

Evil Monkey
August 3, 2007, 01:26 AM
I think it's nice that people want to progress and figure out new things and such in the small arms world but "The Ultimate Combat Round" is extremely unnecessary. What militaries are using today WORKS.

The 5.56mm & 7.62mm NATO combo works. The amount of money needed to change from these two rounds to a 6-point-whatever is too much to make a difference on the field.

Even if there was a change, eventually there would be specialized rounds for each platform, rifle, MG, marksman rifle. Look at the Chinese and their 5.8x42mm round. They have a standard loading for the rifles, a heavy load for LSW's and their "GPMG", if you want to call it that, and they also have a sniper loading for their marksman rifle!! WHY!?! If you're going to specialize, wouldn't it just be better to use a bigger or smaller round depending on the application?

Their QJY88 5.8mm GPMG utilizing a heavy loading was found to be unsatisfactory at longer ranges of 600+ meters. So now they use it as a squad machine gun and went back to the PKM 7.62x54mm for GPMG use.

GunTech
August 3, 2007, 01:41 AM
Nolo,

FYI, your 6x45

http://guntech.com/ammo/6x45nolo.jpg

GunTech
August 3, 2007, 01:51 AM
This has been very interesting ! How about we lose the cartridge all togetherwe use a combustion chamber and an electrically ignited liquid fuel ,with a magazine full of projectiles ! Nothing to eject and a very short action as it only has to chamber a projectile !when you switch the selector to full auto ,it also turns down the metering on the fuel /propellant for lower velocity and recoil resulting in better controll ??!! What do you think ? Kevin

For a start, read "Liquid propellan gun technology" by Klingenberg, Knapton, Morrison and Wren. Then ask yourself if you want any of the chemicals being used in experimental LPG monopropellants or Binaries anywhere near your body parts.

Looking at a few of the hypergolic bipropellant fuels, we see nice stuff like hydrazine, amino alcohols, unsatured hydrocarbons and various heterocyclic compounds. For the nonhypergolics fuels, stuff like N-octane, N-hexadecane, JP4, Isopropanol and decahydro-naphtaeln are popular.

Of course, being bipropellants, you need to mix the fuel with an oxidizer. Currently in vogue are things like white fuming nitric acid, red fuming nitric acid, hydrogen peroxide, di-nitrogen tetroxide etc.

Monopropellants look much better. Stuff like methyl nitrate, nitomethan, exthelene oxide hydrogen peroxide and hydroxilammonium nitrate are popular. In addition there are monopropellant mixtures - scary witches brews that don't requite an oxidizer.

I'll pass.

GunTech
August 3, 2007, 02:01 AM
Evil Monkey,

No doubt cost rules the day, when you buy rifles and ammo by the cargo ship load. But it certainly looks like there are rounds that would do very well as general purpose cartridges replacing both the 5.56x45 and 7.62x51 with a single round. That simplifies logistics. As I noted, you can optimize mission by simply changing loadings of the same cartridge if necessay.

The 6.5, in it's varying guises, has more energy at short ranges than the 5.56x45mm - with manageable recoil, while at longer range, the higher BC and sectional density allow the 6.5 outperform the 7.62x51.

There would be a huge advantage to have a single round of ammo for all your assault rifles, DMR, Sniper rifles, LMGs and GPMGs.

Yes, it would be costly, but the cost of adopting annew cartridge pales in comparison to more sexy DOD projects like tanks, planes, etc.

Of course, the boot on the ground get's last consideration. Managing a project like a new rifle isn't sexy, and doesn't get you noticed at the pentagon the way a new missile, tank or plane does.

Utimately, the real deciding factor is that the rifle has basically reached it's peak. The military is interested in the next thing. The OICW is the start of the concept, and directly addresses issues with the current military rifle.

Even so, the M16 is now America's longest serving rifle. Maybe we should thing of some interim solution to last us until the next great leap forward.

Tony Williams
August 3, 2007, 02:53 AM
Yes, Tony Williams, recoil can be a non-issue if we choose the right weapon. In otherwords, a weapon that either uses constant recoil, the laterally moving breechblock system or a balanced action.

Some such devices may change the nature of the recoil kick experienced by the shooter (by making it softer but longer, as opposed to short and hard), but there's no escaping Newton's Third Law (for every action, there's an equal and opposite reaction). Only a muzzle brake or suppressor will actually reduce the recoil impulse generated by firing a cartridge.

Nolo
August 3, 2007, 05:07 AM
No, muzzle brakes will not, TW, they, just like all of these other methods, merely reduce felt recoil. The recoil is still there. Nevertheless, reducing felt recoil allows your rifle to fire longer on full auto, keep on target and do important things like shove more rounds into more important parts of your enemy. Just watch videos of the KRISS and AA-12, and tell me that they don't work (which, to me, seemed to be what you were impying).

As for all the money issues, I never said anything about the U.S. miltary adopting this technology. Just check, I never did. I'm not going to go over it, I don't recall saying it, so I'm pretty certain that I never did in this thread.

I'm merely trying to optimize.

Tony Williams
August 3, 2007, 05:31 AM
No, muzzle brakes will not, TW, they, just like all of these other methods, merely reduce felt recoil. The recoil is still there.

Sorry, but you are wrong there. Recoil is generated by two elements: one is the bullet weight and muzzle velocity, the other is the propellant weight and the velocity of the gasses as they escape the muzzle - a kind of "rocket effect". In a typical high-velocity military rifle cartridge, about 30-40% of the recoil impulse comes from the propellant gasses. So if you can stop these gasses from rushing forwards but turn them to one side (or even better, to the rear) you will lose the rocket effect or even turn it slightly to your advantage. And that's what a muzzle brake does.

Of course, you can never trap all of the gasses - some will escape through the hole in the muzzle brake which the bullet passes through, others will pass on either side of it - but a good design can significantly reduce the actual recoil. If it is arranged that a part of the gasses vents upwards (as with the AK-74's brake) then the downward push helps to counteract muzzle rise as well (in that instance, it's acting as a compensator as well as a brake).

Suppressors trap and slow down much of the gas, letting it leak out of the gun more slowly, so they reduce recoil as well.

You can find out how to calculate the two different elements of recoil in this article on my site: http://www.quarry.nildram.co.uk/ballistics.htm

As far as gun design is concerned, this can have a minor effect on actual recoil (a gas-operated gun bleeds off some of the gas which would otherwise be rushing out of the muzzle), but most of the effects are concerned with reducing the perceived recoil, usually by smoothing out the recoil pulse over a longer time period. The benefits can be considerable, but the firer still gets pushed back by the same force. The shape of the stock is also important in affecting perceived recoil.

GunTech
August 3, 2007, 07:42 AM
There's also 'soft recoil' systems - primarily used on artillery, but employed on weapons like the XM-307/XM-312. In this case, the barrel and action are held to the rear under spring tension. On firing, the barrel and action are released, flying forward and firing when the action and barrel have attained maximum velocity. Recoil has to overcome this forward momentum, significantly reducing recoil.

Whether this technique can be utilized successfully is another matter. A well designed muzzle brake is much simpler.

How much difference will a muzzle brake make? As Tony noted, recoil is caused by both the bullet and the escaping propellant. In the case of our 6.5x45 round, lets look at the before and after, assuming a muzzle brake that completely eliminates the effect of the propellant gases (ideal case).

Again, the reference rifle weighs 9 pounds.

Bullet Ipulse Free Recoil Free Energy
M855 1.3 4.5 2.9
6.5 w/o 1.9 6.8 6.5
6.5 w 1.4 4.8 3.3
M43 1.9 6.8 6.4
M80 2.5 8.9 11.1


Naturally, it is unlikely that 100% of the recoil created by the escaping propellant gases will be eliminated by the brake, but a well designed brake will have a large impact on recoil (as anyone who has fired one of the various 50 caliber rifles can attest.)

Note in the above, the braked 6.5 has less recoil than the 7.62x39mm and only slightly more than the 5.56x45mm.

If anyone doubts that recoil brakes work, here's a rather poor video of a test of a muzzle brake I designed, fitted to an aluminum receiver FAL weighing a mere 7 pounds. Please note that I am firing this rifle off my chin. Without a brake, this rifle should generate a recoil impulse of 2.5 lbs-sec, a free velocity of 11.5 fps and a free energy of 14.4 ft-lbs.

http://www.guntech.com/muzzle/muzzle_mpeg2.html

Here's a close up of the barke in question:

http://guntech.com/muzzle/newmuzzle2.jpg

Tod

Nolo
August 3, 2007, 12:52 PM
They reduce felt recoil by counteracting the recoil the rifle through redirecting the gases. Recoil is just about impulse, the opposite impulse from the energy of the round, which there are various ways to counter.

Either way, there are known ways to counter it, so the discussion is moot.

Oohrah
August 3, 2007, 02:21 PM
Presently a report states that 30,000 rounds are used per target. Marine
NCOs have given up their M9 and they have been replaced with A-4
rifles. We are giving supposedly friendly Iraqi troops M-16s in trade for
those AKs. At distance, the 223 is the same no bullet energy crap that
it always has been, even with all the modifications made over the years.
Double tap training kind of proves it is not an effective round in it's
ball form. Makes you wonder why there is a shortage of this not so
great round? Is it because the amount of rounds expended per target,
or because we will arm potential enemies. Pretty sad when our main
supply of ammo comes from other countries like Israel to take up the
slack. Wonder if we still get our combat boots from China!!! There
was nothing wrong with the 7.62x51. Why we got into a less effective
mode is beyond me. I think the spray and pray has put us back to
where they have to fix don't work to may work!:fire:

GunTech
August 3, 2007, 04:22 PM
7.62x51 is not usable under full auto, and weighs too much. Remember, 90% of all infantry fire occurs at 300 yards or less, 80% at 200 yards or less and about 70% at 100 yards or less, regardless of terrain. During WWII, the average range of engagement was about 70 yards.

There are times such as assaulting where auto fire is appropriate. It's also useful for fixing the enemy during fire and maneuver. The effectiveness of 'aimed fire' under combat conditions is overrated.

I'll quote myself from another post on the subject


The assumption of long range performance is based on what I call the "Rifle Range Mentality". The fact of the matter is that studies have consistently shown that the infantryman is not able to engage target over about 300 meters, regardless of how accurate the weapons is *(note that this is infantry combat, as opposed to sniping).

The whole rationale of the assault rifle is built around this fact. The reality is that most rifle fire occurs at 100 meters or less. *I've posted more detailed explanations of this on this list before. Those conclusions (and other more interesting ones) are drawn from Hitchman's "Operational Requirements for an Infantry Hand Weapon". Hitchman based his analysis on the ALCLAD study.

During the Korean war, as study on the effectiveness of body armor was commissioned and was later known as ALCLAD (sorry, I don't know what that stands for). One of the factors that became apparent during ALCLAD was that there had never been a detailed analysis of how hits are incurred in combat. Careful analysis was made of all casualty reports from WWII and Korea (data from Vietnam and the Arab-Israeli conflicts was later added and proved the validity of the model.

Hitchman and the ORO made use of this data for their report . Many of their conclusions were controversial, but to date no one has been able to dispute them scientifically. Here are some of the relevant quotes. As the 'Fireside Theater' said, everything you know is wrong.

Quoting Hitchman (and with my own comments):

"Rifle fire and its effects were deficient in some important military respects...in combat, hits from bullets are incurred by the body at random:..the same as for fragment missiles..which are not 'aimed'...Exposure was the chief factor...aimed or directed fire does not influence the manner in which hits are sustained...[Despite] evidence of prodigious rifle ammunition expenditure per hit,..the comparison of hits from bullets with those of fragments shows that the rifle bullet is not actually better directed towards vulnerable parts of the body"

If time and degree of exposure was the chief factor in whether a hit was obtained, what was the point of long range shooting? Further, analysis of actual combat in showed that 90% of all rifle fire occured at 300 yards or less and that 70% occurs at 100 yards or less. Interveneing terrain, camouflage and an inability to adequately identify targets were cited. Indeed, the effectiveness of rifle fire drops rapidly to zero at ranges greater than 300 yards.

Hitchman continues:

"It is interesting..that at all common ranges weapons errors are without significance in the man-weapon system...the dispersion of the weapon could be more than double without materially affecting the probability of hitting the target...weapons-design standards which seek perfection by making the rifle more accurate (approach zero dispersion)..are not supported by this analysis as genuine military requirements. Errors in aiming have been found to be the greatest single factor contributing to the lack of effectiveness of the man-rifle system...[in combat] men who are graded..as expert riflemen do not perform satisfactorily at common battle ranges."

"Either a simultaneous [salvo], or a high cyclic rate burst, with the number of rounds per burst automatically set rather than be dependant on the trigger release. In the (single barrel burst) design, controlled nutation [nutate: to nod or droop] of the rifle muzzle would provide the desired shot dispersion or pattern; in the..(salvo), the scatter would be obtained and controlled by multiple barrels, a mother-daughter type of projectile, or projection of missiles in the manner of a shotgun."

Nolo
August 3, 2007, 04:25 PM
That is the reason for this thread; to improve the effectiveness of the combat rifle.

GunTech, could you run me a 5.45x39mm round necked up to 5.75mm with a 80, 85 and 90 grain bullet? What kind of speed and energy do I get?

GunTech
August 3, 2007, 04:30 PM
They reduce felt recoil by counteracting the recoil the rifle through redirecting the gases. Recoil is just about impulse, the opposite impulse from the energy of the round, which there are various ways to counter.

Actually, propellant gases cause about 1/3 of the of the recoil generated. Bear in mind that Newtons law require an equal and opposite reaction. It not just the bullet going down the barrel, but anywhere from 25-50 grains of powder, converted to combustion products and moving at around 4000fps.

If you redirect the gasses, their forward momentum does not contribute to recoil to the same extent. If you direct the gasses rearward, it can actually counter act the recoil generated by the bullet.

GunTech
August 3, 2007, 04:37 PM
Presently a report states that 30,000 rounds are used per target.

That means troops are getting better. The ratio in Vietnam was closer to 1000,000 round per casualty.

BTW, those number are deceptive. The vast majority of rounds are spent fixing the enemy, providing cover and suppressive fire and basically trading ammunition expenditure for casualties. I'll gladly burn ammo to save servicemen's lives.

The low rounds count per casualty ration in WWI (7,000 rounds per casualty) is miore reflective of the iddiotic tactics of the time than superior marksmanship.

30,000 round per casualty is about equal to WWII, and better than KOrea and Vietnam.

Do you have a cite for this data? This reflects a radical change in ammo expenditure per casualty.

Nolo
August 3, 2007, 04:37 PM
Okay.
My point was, it works.
We know it does. So there is no reason to bicker about why. :D

GunTech
August 3, 2007, 04:56 PM
GunTech, could you run me a 5.45x39mm round necked up to 5.75mm with a 80, 85 and 90 grain bullet? What kind of speed and energy do I get?

Unfortunately, I am stuck with bullets in the database, so unless I build a 5.75 bullet, such a task isn't doable.

It should be noted however that without changing the allowable pressure or case capacity, minor changes in bullets won't have much of an effect. You can trade things like short range energy for long range performance, but ultimately, you are just trading back and forth, not gaining.

A good example is the 6.5 Grendel. There are some good gains over the 5.56 because you are blowing out the case and sharpening the shoulder, and running the cartridge severa thousand psi over the 7.62x39mm. That will make a difference.

Now consider the 6x45 vs the 5.56x45 - the same case necked up to 243.

Muzzle velocity drops, meaning less muzzle energy. You trade short range energy for long range energy because the 243 bullets tend to have much better BC. You can also adopt a 223 bullet with better bc, and you get similar performance.

6.5 bullets, at moderate weights, tend to have very good BC. If yourt drive them at relatively decent velocities the have plenty of energy, and retain it well. Note that the 308 has much more energy, but the existing ball ammunition has relatively poor BC, so that the 6.5, starting slower and with less energy than the 308, eventually surpasses that cartridge (at around 500 yards)

There are high BC bullets for 308, but these tend to be heaver, meaning more recoil, every thing else being equal.

The real trick is to develop a cartridge that does a lot of things well, even if it doesn't do one thing really well. It a case of generalization versus specialization. If you have one round for machine guns, one for assault rifles, one for DMR and one for snipers, you can optimize each one for that one specific job. Of course, you've created a logistical nightmare, because now you have to supply 4 or more catridges.

Logistics is a huge factor in winning wars. So build you cartridge right, and possibly you can hace one round that performs pretty well in an assault rfile, not too bad in a machinegun, fairly decent in a dmr rifle and adequate as a sniper round.

And that is a very good thing.

The 6.5x45 decribed above is going to be a little too powerful for light and compact assault rifles - you are going to want to add a brake. It will be great for semi-auto fire, but much less contyrollable in autofire than 5.56.

In a full sized rifle with a 20 inch + barrel, it will do very well at intermediate range, and with good sectional density, shoud be good against walls and such.

Put it into a 24 inch DMR, or a prescision built 26 inch sniper rifle and it should be plenty accurate. If necessary, and where recoil isn't a factor, you can load the same round with a heavy, very high BC bullet and get long range performance that rewally shines - superior to M80, and very clode to M852 or M118LR special ball.

The rifle requires no change, and can be based on the same platform as the basic military rifle - highly refined and with match grade parts. in a pinch, the sniper can still shoot the general issue ammo, just losing some accuracy and long range performance. This is much more desireabe than issuing a completely separate catridge with a separate logistical train.

One Round to rule them all, One Round to find them,
One Round to bring them all and in the darkness bind them."

Nolo
August 3, 2007, 05:08 PM
Here's how I see it as far as logistics is concerned:
2 rounds. Make two rounds, each specialized to the opposite ends of the spectrum. DMR (I am excluding sniper because they are already specialized and can make their own choices for ammunition) and GPMG effectively can use the same round. There is not enough difference there (in my mind) to warrant a separate cartridge for each. You can (and should) also cater that cartridge to snipers because it is easy, DMRs are pretty close to sniper requirements. I think that for those missions, a 7mm or 6.5mm bullet is ideal, with a case between the 6.5 GunTech's and the 7.62 NATO's. So that leaves PDWs and assault rifles. They can easily share a round, if one uses a low-end cartridge like 5.56 or 5.45. So I'm basically, at this point, focused on improving that cartridge. How I think that might be achieved is by improving the bullet of the 5.45x39mm cartridge, and the first idea I had was necking up to 6mm, but that proved to be too much. So now I'm thinking of somewhere in between. Well, exactly in between is 5.75mm, so that's why I asked about that. I want to see the data for 80, 85, and 90 grain bullets as pushed by that case. The closer you can get to 5.75mm for the bullet, the better. 5.8 would work.

Also, can you give me a comparison of the powder capacity of the 5.56mm case and the 5.45mm case? I'd very much like to see which one has more powder.

Nolo
August 3, 2007, 05:34 PM
Here are some calibers that would work, provided they had the proper weights:
.225
5.6
5.7
5.8
But, again, I don't know what the bullet weights for those are.

GunTech
August 3, 2007, 07:37 PM
If you are going to have two cartridges, there's little reason to change the current 5.56x45mm and 7.62x51mm, IMO.

Nolo
August 3, 2007, 08:38 PM
Little reason, yes, GunTech, but I don't need a reason to develop something. Most often you will find that I do stuff because I can. I can make a better bullet, and I want to. Plus, I'm trying to beat the 52000 EPP of the 5.56. That's a big enough reason for me.

JWarren
August 3, 2007, 08:50 PM
Nola,

I see your reasoning on the term 'Gun hose." It's something to think about. It may be a good idea to start a seperate thread to consider this and any terminology associated with it.

Putting it in this thread would take away from the quality discussion you guys are having here. Thanks for this, and thanks for clearing up the "Gun hose" reasoning.


-- John

Nolo
August 3, 2007, 08:57 PM
You're quite welcome.
This thread was solely about the assault rifle anyway, and I was going to start a thread on the other two later, so I may just do that.

Bigfoot
August 3, 2007, 10:07 PM
Look at the 6.5x52mm Carcano case. A tiny bit wider than the 7.62x39 and 6.5 Grendel so it fits and feeds well in 6.5 G magazines after shortening. New brass is available from Norma.

raubritter
August 3, 2007, 10:19 PM
If I was really going to standardize an assault rifle cartridge, it would simply be the 7.62x39 necked down to 7mm, using a 100grn steel core. That would have a good BC and shoot flatter.

Nolo
August 3, 2007, 10:26 PM
The beef I have with that is weight. I bet it wouldn't exceed the EPP of the 5.56mm.
Feel free to calculate it for me.
Really, the Grendel case is about as wide as I want to go, so too with the Carcano case. I'd shorten it up anyway, which would end up being basically the same thing as the 6.5x45 GunTech.

GunTech
August 3, 2007, 10:39 PM
If I was really going to standardize an assault rifle cartridge, it would simply be the 7.62x39 necked down to 7mm, using a 100grn steel core. That would have a good BC and shoot flatter.

In the 100 grain range, the 6.5 has a better BC than the 7mm by a pretty good margin. Why not take a 7.62x39, neck it down to 6.5, and blow the case out to near 'improved' standards.

Crap - we just reinvented the 6.5 grendel :)

Nolo
August 3, 2007, 10:47 PM
Excellent point, GunTech.
Actually, I would like an AK in 6.5 Grendel, will they start making them soon?

Nolo
August 3, 2007, 11:49 PM
Found some very exciting data a minute ago.
Really just realized it had been there all along.
The USA is undertaking a Lightweight Small Arms Technologies development programme, with the aim of halving the weight of the current 5.56 mm M249 (FN Minimi) LMG and its ammunition. Two different cartridge designs are being tested, shown here in comparison with the 5.56x45 (top). In the middle is a polymer-cased telescoped round (by ARES), and below that a caseless round (by ATK) based on HK G11 technology. The linked polymer-cased rounds are showing a 33% reduction in weight over conventional 5.56x45 ammunition, the caseless rounds a 51% reduction. The initial calibre and ballistics have been chosen to match the 5.56x45 SS109/M855 for comparison purposes, but in parallel with this, research is being carried out into using the weight savings to produce a "Company" MG which might replace both 5.56mm and 7.62mm MGs.
http://i200.photobucket.com/albums/aa149/Nolo_photo/AAILSAT1.jpg
Basically, what this means is the EPP of these cartridges is shooting way, way up. Makes me feel kind of stupid for discounting caseless ammunition now. Actually, really stupid.
EPP of 5.56x45mm: 52000 (approx.)
EPP of 5.56 Telescoping: 79000 (approx.)
EPP of 5.56 Caseless: 102000 (approx.)
Those are some stunning figures!
So, here's the question: what problems do caseless cartridges have? Can you have caseless cartridges that fire using caps? I heard that HK (or whoever they had doing the work for them) basically solved the problems associated with the caseless ammunition, but I was wondering if there was any opposition to that statement.

GunTech
August 4, 2007, 12:06 AM
It won;t make you feel stupid when you realize what a pain it is to make caseless ammo work. People don;t aporeciate all the wondeful thikngs the case does. It protects the round from rough handling and non-ideal environmental conditions. It extracts heat from the chamber. It obturates - that is - expands to seal the chamber, and then shrinks slightly so it can be removed fairly easily. It gives the extractor something to grab. Without the casing, you have to deal with all this stuff.

How do you seal the breech?
How do you deal with the extra heat in the chamber
How do you keep the propellant from being damaged by water, oil, heat and cold, etc, etc. ?
How do you protect the integrety of the round from the mechanical handling of the action itself?

It's not as easy as people thing. How many caseless autoweaopons do you see out there - particularly in rifle calibers? It's an attractive solution - ne that has been in development for the military for at least 50 years.

IIRC, there are a couple of aircraft canon that iuse caseless ammo, and that's about it.

Nolo
August 4, 2007, 12:09 AM
Hmmm... I remember that HK seemed to have solved all the problems. The G11 was combat-grade, no? Certainly if I were to try and "adopt" caseless ammo, I wouldn't do it with a conventional rifle.

GunTech
August 4, 2007, 01:07 AM
HKs G11 basically reached the point where it was ready to start undergoing serious field testing. Why developmentally pretty much feature complete, it was in no way a proven or ready for issue weapon.

The main thing that killed the G11, aside from German reunification, was the HKs performance in the ACR tests of the 1980s. The goal was to investigate future rifle concepts and attemp to increase the hit probability of military rifles by 100%.

Entrants in the ACR trials included the Colt ACR using duplex ammunition. Basically a product improved M16
http://img.search.com/thumb/8/88/Colt_ACR.jpg/400px-Colt_ACR.jpg

The Stey ACR a novel bullpup with bottom ejection using platic cases and firing flechettes
http://www.steyr-aug.com/acr1.gif

The HK G11 caseless rifle
http://aster.iespana.es/images/g11c.jpg

The AAI ACR - another flechette rifle built on AAI's (now part of ATK) experience with the SPIW.
http://pages.sbcglobal.net/blyle/images/g_aaiacr.gif

Hughes and ARES dropped out before the ACR tests began. My recollection is that the Hughes gun used a variant of their 'chicklet' plastic cased ammunition, which the ARES AIWS was a derivitive of Eugene Stoners promising FARC.

Nolo
August 4, 2007, 01:43 AM
I see. Couldn't you, however, resurrect and fully develop the G11?

Tony Williams
August 4, 2007, 02:54 AM
There's also 'soft recoil' systems - primarily used on artillery, but employed on weapons like the XM-307/XM-312. In this case, the barrel and action are held to the rear under spring tension. On firing, the barrel and action are released, flying forward and firing when the action and barrel have attained maximum velocity. Recoil has to overcome this forward momentum, significantly reducing recoil.

Yes, it is also known as "differential recoil" or "floating firing" and is common with AA cannon systems. However, it does not reduce the total recoil force (Newton doesn't allow that!). What happens is that the recoil begins as soon as the barrel and action start moving forwards, and continues through the cycle. So the graph of the recoil impulse, instead of showing sharp peaks and troughs with each shot, is much more level, and that makes automatic fire more controllable.

A designer called Robinson produced small arms using this system, during and after WW2 - including a light .50 BMG cal MG which he fired from the shoulder. I don't know why the idea didn't take off for MGs, but as you say the XM307 seems to be the first modern version. For a rifle, the problem is that there is a looong delay before the gun fires after pulling the trigger, during which time the barrel and action is trundling forwards in the receiver and disturbing the aim, so single-shot accuracy would be poor.

Tony Williams
August 4, 2007, 03:01 AM
Caseless ammo does indeed have its problems, but it also has some big advantages, so the question is whether the advantages outweigh the problems. In the case of the HK G11 they probably did - but the ACR trials, in setting a target of a doubled hit probability over the M16, were setting a very high hurdle which none of the competing rifles was able to clear.

It'll be interesting to see how the current lightweight MG trials work out. As I've pointed out in THIS (http://www.quarry.nildram.co.uk/Assault.htm) article, they are also looking at a "company MG" able to replace 5.56mm and 7.62mm MGs, which suggests a caseless or plastic-cased round intermediate between them - perhaps with a calibre and ballistics similar to the 6.5mm Grendel. That would make a good basis for an assault rifle too...

Nolo
August 4, 2007, 01:30 PM
Tony, I'd like to see a point-by-point discussion of the benefits and disadvantages of caseless ammunition, if you have one.

sturmgewehr
August 4, 2007, 01:46 PM
Actually, the G11 was no where near ready for prime time. The Germans had field tested it and it had too many problems to be seriously considered as a main line service rifle.

First off, the internals of the G11 were similar in complexity to a Swiss watch.

http://www.hkpro.com/image/g11open.jpg
http://www.hkpro.com/image/g11bolt.jpg

Could you imagine getting that thing wet or, God forbid, muddy? Yeah, that won't last long in a war zone. A military rifle must be simple, easily maintained and reliable. The G11 was none of none of the above. It was a great concept, but it had other serious issues...

...like the ammo. It was easily damaged, prone to "cooking off" and the technology just wasn't evolved. It was susceptible to water, the powder would become brittle when stored and ultimately the various prototypes had issues with burning way too dirty (due to the protective coating around the powder).

Here are some of the various ammo prototypes:

http://www.hkpro.com/image/g11round3.jpg
http://www.hkpro.com/image/g11round4.jpg

Most countries have abandon, at least for now, the caseless concept due to the issues mostly related to the propellant.

Nolo
August 4, 2007, 01:59 PM
The HK's internals, at least in theory, would be completely shut off from any damage, due to the sealed weapon (no ejection port).
Also, the ammunition you have shown there was prone to cook-offs, which is why they switched to the other HTIP propellant (which you can actually see in the picture of the field-stripped G11).
And, yes, the internal mechanism was complex, but I think you could simplify it significantly if you redesigned the weapon. I also heard reports that the G11 was quite reliable in HK's famous mudbath tests. But whether those reports were founded or not, I don't know. As for the dirty and "half-lived" cartridges, I've never heard any reports to support that, but on the gripping hand I've never heard any reports to counter it, either.

Owen
August 4, 2007, 02:00 PM
NOLO

do you think maybe that peoplethe with doctorates that design cartridges maybe have a handle on the efficiency curve and are riding it with their designs?

You're trying to stuff 10 pounds of crap into a 5 pound bag, and wondering why you have poo on your hands.

sturmgewehr
August 4, 2007, 02:06 PM
The HK's internals, at least in theory, would be completely shut off from any damage, due to the sealed weapon (no ejection port).
That's what they thought originally, until they had a bad round and it couldn't be ejected to clear the weapon without field stripping. It would also make unloading the weapon troublesome as well... so, an ejection port is in fact required.

Nolo
August 4, 2007, 02:09 PM
I do not understand what you mean, sir.
If you are saying to me "stay away from our area of expertise, we know better, f00l", then all I have to reply to that is:
Kalashnikov as a young boy liked taking things apart, and he liked experimenting.
Eugene Stoner was an inventor from a young age.
You started doing designs before you got your doctorate, I'm sure.
If you think I'm wrong, correct me, don't deride me.

Nolo
August 4, 2007, 02:11 PM
Touche, Sturmgewer. It was on the underside of the weapon, no?
I wonder if they did the mudbath tests on the prototype with the ejection port.
See, we need more data!
We don't have it.
Ressurect and redesign G11!

sturmgewehr
August 4, 2007, 02:12 PM
This round:

http://www.hkpro.com/image/g11round4.jpg

Is the HITP round.

sturmgewehr
August 4, 2007, 02:13 PM
I wish the project would have continued, it was promising... and those who fired the G11 were amazed at how easy it was to hit targets out to 300m with multiple rounds (it fired 3 rounds so fast it almost sounded like one shot).

Let's harass HK into bringing it back. :D

Nolo
August 4, 2007, 02:18 PM
Yes, let's.
And that is the early HITP round, the final rounds did not have a protruding bullet:
http://i200.photobucket.com/albums/aa149/Nolo_photo/g11_ammo.jpg
The final variant is the one on the right.

sturmgewehr
August 4, 2007, 02:26 PM
Yeah, I couldn't find a pic of the later round. Obviously they pushed the bullet back in the case to help protect it from damage.

The design was really unique as it had a booster charge just behind the bullet that ignited and pushed the bullet forward, before the rest of the propellant ignited so that it could actually push the round down the barrel vs. just burning around it... it was something of a two stage design, totally unique. I've heard that it too had its share of reliability problems.

Nolo
August 4, 2007, 02:28 PM
Something like that.
And, strangely, I too couldn't really find a good picture of it either, though I've seen one before.
Yeah that was an interesting design.
If you took the trouble to work on the G11 some more, you'd end up with a truly revolutionary weapon.
I'd put it in 5.5mm, though.

Owen
August 4, 2007, 02:36 PM
I don't have a doctorate, but there are a lot of people in the ballistics field that do.

It's just that you seem surprised that you can't escape the curve generated by existing cartridges. Considering the 130 years plus of development, you're trying to make a radical improvement on an existing, mature technology. In all likelihood, with existing propellents, we are within a few percent of the peak performance for cartridge firearms.

The advances aren't going to come from drawing a new cartridge shape in MS paint. That's already been done. You know that Quickoad program the GunTech is using? The cartridge designers have been using stuff like that for decades. The differnce is that they try hundred of variables at once, generate curves and pick the sweet spots. To the point where they say "I want this ME with this bullet in this length, with the minimum amount of propellant, so me what we can do"

The advances in conventional firearms are going to come from finding better propellants, better materials and ergonomics. Otherwise we are just rearranging deck chairs. 2 of those things are only going to come from a laboratory. TANSTAFL

The G11 is certainly a viable path, but i think you will find that designing on a napkin is a walk in the park compared to building the hardware.

The G11 bankrupted HK, and put a serious dent in Dynamit-Nobel.

(BTW easy on the ashingbay of onyTay illiamsWay He knows what he's talking about. Recoil is all about impulse, and a muzzle brake creates a counter impulse)

Nolo
August 4, 2007, 02:45 PM
I didn't bash him.
I merely disagreed, then realized I was wrong.
I'm allowed to be wrong, no?
The whole thread was designed for me to learn from you, not the other way around. And I did. Most of what I learned was exactly what you said ('cept the napkin stuff, I already knew that, hence the thread). It looked like I had a way out, but it turned out to be a dead end. Which is why I'm now looking at caseless ammo. And it's TANSTAAFL, buddy. Two "A's" in the last part. I don't have the ability to even run data through a computer, much less experiment with cartridges in the real world. I discounted caseless ammo and other things because they weren't perfected and no amount of talk on an internet forum will change that (that's still true). However, bringing cartridge data onto the forum with know and tried and true technologies will get us somewhere. If only half a step forward, it's still progress. And the G11 only bankrupted HK because they put a Hell of alot of time and effort and money into it and did get any reward. That'd bankrupt anybody.
The point is, I think I have something to contribute to you, but I think you have far more to contribute to me.

Owen
August 4, 2007, 03:14 PM
you can get the ability to run data pretty easily. The program GunTech is using is called quickload/Quickdesign

http://www.neconos.com/details3.htm

It looks like it'll cost about $300 for the package, which is cheap if you're serious about this.

I haven't played with it much, because I mostly use handguns, and care alot more about shooting than ammunition. Once I find a load that works the gun, and hits the target reliably, I stop development, and crank out 10 or 20k rounds. When I was working as a designer, the ammuntion was a constant, so I didn't really play with it then, either.

http://www.neconos.com/details3a.htm

Buy a physics text book, and a drafting/detailing book. Mechanical design is something you can do on your own. You might want to dig up a copy of Cartridges of the World.

Tony Williams
August 4, 2007, 03:18 PM
A quick summary of pros and cons of caseless ammo, with the HK G11 specifically in mind.

Pros:

1. Ammo weight about half that of a brass round - especially important for MGs, but useful for any poor grunt carrying a huge load (as they do).

2. The action stays shut as it operates - it doesn't open to let in dirt which might jam the mechanism (G11 does have an ejection port, but it's only opened to clear the chamber after firing, or if there's a faulty round).

3. There isn't a case to eject - faulty ejection is a significant contributor to jams.

Cons:

1. Ammo is fragile (G11 met this by providing it in sealed magazine packs)

2. Risk of cook-offs due to lack of brass cases, which remove heat from chamber (Dynamit Nobel pretty well cracked this with insensitive propellant).

3. No brass case to seal the chamber (seems to have been sorted in G11 - it just makes the breech design more difficult).

Clearly, the US was sufficiently impressed by the G11's ammo technology to buy the rights to use it from Dynamit Nobel. It is now being developed for the LSAT MG.

Nolo
August 4, 2007, 04:00 PM
Yeah.
Sounds good, with the caseless stuff. Nothing that can't be overcome with development.
Oh, Owen, I don't have $300. I just don't... yet. I'm already on track to become a ME, so that's not an issue, it's what I was going to do anyway.

PercyShelley
August 5, 2007, 05:41 AM
There are those of us who are of the opinion that, since muskets lacked metallic cartridges, caseless ammunition clearly represents a step backwards.

:neener:

Actually, if a semi-auto caseless rifle is ever made in the US, I will be first in line to buy the thing, as a salute to brave engineers as much as to the great interest I have in the concept itself. Besides, my AR needs company, and I refuse to house it with one of those poorly bred mongrel AKs!

There is another, less discussed method of improving firearms efficiency I've been peddling about in my head.

Consider the following:

http://www.z-hat.com/Efficiency%20of%20the%20300%20Hawk.htm

About a third of the energy contained in a cartridge becomes waste heat; absorbed by the barrel, action and casing. This heat both fails to propel the bullet any faster and impairs the proper function of the firearm.

If the barrel of a firearm could be lined with a sufficiently hard and insulative substance (ceraplate has been recommended), not only could the barrel be made thinner and lighter, because it would no longer have to function as much as a heat sink, but velocities would improve.

I pitched this idea to Chris Byrne at the Anarchangel blog, and he says that it will cause a lumpy pressure curve that would destroy accuracy (as I understood his words). I'm not so sure; I would think that it would produce a pressure curve that drops off less dramatically towards the end, which would just increase velocity. It is worth noting that Chris Byrne is a trained engineer, and I am not.

Liquid propellants were mentioned earlier, esp. hydrazine, which is one of the nastiest chemicals that man regularly puts in his machines (it's used in the shuttle and F-16 APUs, as well as many satellites). HAN-based monopropellants are much less toxic, and have a higher specific impulse, which should net you some gain in velocity when used as a gun propellant.

GunTech
August 5, 2007, 11:20 AM
BTW, just because we are gtting into exotica, another solution to the weight/capacuty/energy issue of cartridges is to use a technology like CAP/ET/ETC.

The limiting factor in conventional cartridges pressure is the aability of the chamber to handle peak pressure. Unfortunately, conventional propellants have a sharp pressure spike, while the pressure profile of the barrel is much broader at peak pressure.

If you replace propellant gases with a plasma stimulated working fluid, you can control the pressure curve to match the characteristics of the barrel. The net result is that you can have huge increases in velocity without an increase in case size or peak chamber pressure. The the 1980s Hughes demonstrated a modified M16 that used ET (electro-thermal) to almost double the velocity at the same peak pressure. The the main issue with ET and ETC (Electrothermal chemical) rounds is the demand for externl electrical power. With a whole new generation of supercapacitors on the horizon, ET and ETC guns could become viable very soon.

As Tony noted, there are compelling military reasons for caseless ammo and the weapons that use it. Anyone who has lugges around a lot of ammo and other military impedimenta will immediately recognized the appeal in a reduction of size and weight. The problem is that the military environment is incredibly unforgiving.

There's little civilian appeal for caseless ammo, as there is typically a demand for a large variet of loadings in any given caliber and no ability to 'reload'. Caselss ammo makes most sense when you are manufacturing huge quantities to exactly the same thing. The material making up caseless ammo also tend to be more expensive than standard propellands, offsetting any cost savings.

Finally, my recollection is that HK had issues with their ammo and creating a tracer round. And a lot of traditionally minded infantry types were really keen on going to a bullet that was even smaller than the 5.56x54.

As an aside, there have been at least two civilian firearms that used caseless ammo, and neither was a success. Google 'Daisy VL' and 'Voere VEC 91'

PercyShelley
August 6, 2007, 12:42 AM
Electrothermal propulsion is interesting, but current batteries don't have anything like the energy density of chemical propellants. I don't think you could shave enough weight off the barrel to make up for the massive power cells you would have to haul around.

GunTech
August 6, 2007, 01:21 AM
As noted, awating something like the new carbon-nanotube based supercapcitors. Not that ET and ETC weapons relay on plasma stimulated working fluid - sometimes in conjunction with chemical propellants (ETC). PSWF expand at a rate much faster than chemical propellants as well. There a reason why you don't see velocitie much over 4000 fps. The theorertical max rate of propellant gas expansion is under 6,000 fps, and realistically under about 5,000. PSWF don't have this same restriction.

In any case, I was amazed at how little power ETs actually require, since you are only converting a small amount of working fluid into plasma - typically about 5%. And being able to 'throttle' the pressure means you can match the pressure profile of the barrel. Ig battery technology ever becomes light enough and cheap enough, you could dispense with propellant and use something like water. I'm not sure there are any useful military applications, but it an interesting though - you could vary your by changing the electrical pulse - just dial the power up or down.

At this point, we are really getting into speculative stuff. I don'y see anything like that in the near future. Caseless, if it ever comes, will be first. And it looks like the military is favoring railguns over ET and ETC research these days.

Anteater1717
August 6, 2007, 01:21 AM
7.62x45

PercyShelley
August 6, 2007, 01:41 AM
At this point, we are really getting into speculative stuff. I don'y see anything like that in the near future. Caseless, if it ever comes, will be first. And it looks like the military is favoring railguns over ET and ETC research these days.

Any gun that relies on a working fluid to propel the missile will be limited by the speed of sound in that working fluid. Using HAN as a monopropellant or ETC would give you better performance than conventional gunpowder because the reaction products are lighter and therefore have a higher sound barrier. It's a similar problem to wringing specific impulse out of a rocket really.

The best working fluid would be pressurized monoatomic hydrogen; but show me the barrel material that could stand up to that again and again.

Railguns have a much higher fundamental speed limit; c as far as I know. I don't think that they're as energy-efficient as ET propulsion, but when you're desired end product is a ground-based hypervelocity ASAT or ABM weapon, energy efficiency can take a back seat.

I agree, however, that this is all pie-in-the-sky for those of us without extensive home laboratories and powerful capacitor banks. For the rest of us, there's http://www.powerlabs.org/ .

If we limit ourselves to more proven technology, how much could be gained by electrical ignition? It occurs to me that the primer has to be some sort of limiting factor on case pressures, and that the time between pulling the trigger and the hammer coming down affects accuracy.

zinj
August 6, 2007, 01:42 AM
I think the jump from metallic cartridges to caseless ammunition is too great a leap for right now. Rather, why hasn't serious research been applied into following the shotgun shell's lead and switching to plastic cases?

They are cheaper and lighter than brass, yet don't have the drawbacks of caseless ammo. Plus the technology is already well established; I'm sure a working design could be produced in less than a year by a committed team.

Evidentally one company did try this (NATEC), producing plastic cased ammo with a brass base. However, I would go for an all plastic design, like Activ shotgun shells*. This would be cheaper to manufacture, and weigh even less.

The benefits of this ammunition would be great. If the same cartridge design was kept the ammunition would function in all guns currently in inventory, while allowing more ammunition to be carried. If you went the other direction and upgraded weapons a new cartridge could be developed that was more effective than the previous issue yet weigh the same.

*The brass base on modern plastic shotgun shells is purely decorative. On paper shells it served the purpose of sealing the chamber, and helped to prevent the power burning through the hull when fired (hence the association of "High-Brass" with greater power.)

GunTech
August 6, 2007, 01:52 AM
Shotguns work at significantly ower pressure than rifles. You'd need a plastic that had the strength or ordnance brasse. Not saying it couldn't be done, but it would take work.

I tried the 223 half plastic cases in my AR, and had all sorts of problems. I don't know if it's the case, or the loading, but they weren't reliable. A stub case should work - with a plastic body and a brass base for obturation and to stand up to the extractor.

Of course it's not reloadable, and I don't think it was significantly cheaper at the time. That might be different now.

Tony Williams
August 6, 2007, 02:41 AM
Plastic cases are being tried as an alternative to the caseless rounds in the LSAT project. They are entirely plastic, and telescoped (the bullet is buried within the case). However, they only deliver a 33% saving on weight rather than 50%, and are bulkier.

You can have all-plastic versions of revolver ammo (they exist) but not of conventional self-loading rifle ammo, partly because of the pressures but mainly because the rim can't be made strong enough to resist being ripped up by the extractor as it tries to yank the fired case from the chamber. You need a different kind of gun action to handle all-plastic cases.

Nolo
August 6, 2007, 10:57 AM
Here's something:
http://i200.photobucket.com/albums/aa149/Nolo_photo/enchim9.jpg
Knox Engineering Company (or Corporation, I can't remember) is developing (or has developed, I'm not sure how far along they are) a powder that uses only 1/3 the weight of normal propellants. Basically this means that a cartridge like the 5.56 can be *gasp* straight-walled! Yes, they figured out pressures and everything (GunTech, that's why I asked you for the 3000 f/s 6mm cartridge) by telescoping the round (i.e., a small charge in the base pushes the bullet [and, in this case, some of the charge] forward before the rest of the powder fires to create a bigger chamber). Thus, I created the 5.56 Firebrand:
http://i200.photobucket.com/albums/aa149/Nolo_photo/5.56mmFA.jpg
which has the bullet (a 90-grain) buried in the case (which is the same diameter as the original 5.56) and sealed off with a plastic cap or crimp (similar to a shotgun shell). It should (though I haven't calculated internal volume) be able to push the 90 grainer to 3100 fps.
Oh, and if I'm not mistaken, this will give you a 30% weight saving. Also, it (the length) allows you to put the magazine in the grip of the rifle (the rounds are approximately the same length as a 7.62x25 Tok), greatly improving balance, and creating a "half bullpup".
By the way, thanks to raubritter for the info.

raubritter
August 6, 2007, 02:22 PM
A 90grn 5.56 would be great. A rifle with the magazine in the grip would be very useful, handy, and fast to reload.

Nolo
August 6, 2007, 03:33 PM
I'm about to render the 6mm (100 grain) telescoping improved round and I was wondering whether to use a 9.6mm diameter cartridge or a 10.5mm diameter cartridge.
Can anyone give me a suggestion?

Nolo
August 6, 2007, 04:45 PM
I rendered both.
Anyway, I have a question:
Do I need to modify the cartridge so than all of the powder is behind the center of the bullet? It's not a big problem, I'm just wondering if it's a problem.
Here's my 6mm carts:
http://i200.photobucket.com/albums/aa149/Nolo_photo/6mmFirebrand.jpg
http://i200.photobucket.com/albums/aa149/Nolo_photo/6mmFirebrandBeta.jpg
The top one is short enough to fit in a grip magazine, but the bottom one would make for shorter magazines.
Which one should I keep? They're approximately the same power, I think. It's more difficult to do output calculations with a nonbasic area of powder.
Also, does anyone know if .30 Carbine is used in any grip-magazine loaders? At least comfortably (I think an Automag or Coonan did once, but boy, their grips are wide!).
Could you fit a 40mm long cart magazine in a grip? Comfortably?

Nolo
August 6, 2007, 05:13 PM
Updated to solve the powder-in-front-of-the-bullet problem:
http://i200.photobucket.com/albums/aa149/Nolo_photo/5.56mmFirebrandBeta.jpg
At least I think it was a problem.
The blue stuff should be a lightweight sealant.

Owen
August 6, 2007, 05:30 PM
where does the sealant go?

GunTech
August 6, 2007, 06:29 PM
Instead of sealant, just make it a plastic sabot. It gets dropped once the bullet exits the barrel. Sabots resukt in much lower pressure, usually at the expens of accuracy (e.g. the old accelerator projectiles).
http://www.firearmsid.com/class_tests/images/bt/bt18.jpg

I don;t dount you can have more compact propellants, but I have real doubts about lower pressures. You need a certain pressure to achieve a certain velocity. If you can stretch out the time/pressure curve, you can have lower peak pressure, but you must have the same area under the curve to achieve the same velocity. You can't get around the physics. Let's just say I am dubious about the claims of Knox Engineering.

ET and ETC can get around this, but that is an entirely different, and not really practical solution. Modern smokeless propellants have been under refinelent for over 100 years, and yet no one has found a viable method to significantly alter the pressure/time curve, and if someone does, it will be huge news for the shooting industry.

GunTech
August 6, 2007, 06:40 PM
I always wanted to try 22 sabots in a 30 carbine case. I have no idea how to set up QuickLoad to simulate it.

Here;s 30 caliober compared to a 22 in a 30 caliber sabot. You get the idea.

http://www.reloadammo.com/sabot2.jpg

tinygnat219
August 6, 2007, 07:06 PM
Ummm, it's been around since 1891, the 7.62X54R.

Nolo
August 6, 2007, 08:30 PM
@ owen: Good question. I was thinking about using a burnable sealant, but you'd have to make it so that it wouldn't interfer with the rifle (by gunking it up or such), and I was also going to shorten up the case so that there wasn't as much of it and so that the weight would be lower ('cause it's all just dead space).
@ GunTech: Telescoping solves the problem of pressure. Basically they made the powder burn slightly slower so that it would expand using part of the barrel as the chamber, thus creating enough of a space to not have high pressures. By the time the bullet exits the barrel, it's doing 3100 f/s, and the "delay" is miniscule as to be not noticeable.
As for the sabots, I still want a .22 calber barrel. I think we can get around it without sabots.
@ tinygnat: that was entirely irrelevant.

Owen
August 6, 2007, 09:41 PM
Hey Nolo,

in your search for velocity with manageable pressure, i have a question for you.

Why can a shotgun push a full ounce at 1300 fps, and 6000psi, when a 9mm can only push a 124 grain bullet that fast with 25,000 psi?

I have a hint. F=PA, F=ma.

Nolo
August 6, 2007, 11:58 PM
It's easy. The total force of the projectiles coming out of the shell is increased because the particles have more area in a shotgun shell (as opposed to a 9mm) to push off of. It's like trying to jump off a (taut) wire as opposed to the floor. You just get more energy.
I feel dumb for not trying to include that in my calculations.
:uhoh:
:cuss:

Tony Williams
August 7, 2007, 01:41 AM
Nolo said: Telescoping solves the problem of pressure. Basically they made the powder burn slightly slower so that it would expand using part of the barrel as the chamber, thus creating enough of a space to not have high pressures. By the time the bullet exits the barrel, it's doing 3100 f/s, and the "delay" is miniscule as to be not noticeable.

GunTech has it right: its the pressure of the gas behind the bullet that generates the velocity: no pressure = no velocity. As he said, you might be able to flatten out the pressure curve so that the peak pressure, near the chamber, is lower, but that just means that the pressure down the barrel has to be greater to compensate, otherwise you'll lose velocity.

Nolo
August 7, 2007, 09:14 AM
They don't have no pressure, they just have acceptable pressures. And I'm not sure how they do it, but it seems viable to me.

Owen
August 7, 2007, 09:29 AM
I don't think I understand your analogy Nolo.

Yeah, the larger area of the shotgun wad means that at any given pressure, the overall force on the wad is much higher than it is on, say, a 9mm bullet.

The other side of the coin is that you can't make it too easy for the projectile to go down the barrel, or you won't generate any pressure. The combustion of smokeless powder is dependent on pressure. The higher the pressure, the faster it burns.

Note that shotguns use a very fast powder. Large bore rifles tend to use very slow burning powders. Mull over that for a bit.

Now, can you think of a way to to increse the resistance of the projectile as it goes down the bore? That should help to flatten out the pressure curve.

Nolo
August 7, 2007, 09:35 AM
The powder for the round as I understand it is a slow-burning one, based off and developed from powders used in 40mm cannons.as for increasing resistance, the original charge, which may or may not be made out of conventional powders, pushes the round past the powder to create an optimum chamber size, low pressure (50,000 psi), but still resistant. Essentially, it becomes no different from a 5.56 round at that point. You aren't accelerating (per se) the projectile, I'm sorry if it sounded like that, but the speed of the round does increase, from a push with the initial charge to full velocity instantaneously (relatively).
As for my analogy, you just explained it.

Tony Williams
August 7, 2007, 12:10 PM
You aren't accelerating (per se) the projectile, I'm sorry if it sounded like that, but the speed of the round does increase, from a push with the initial charge to full velocity instantaneously (relatively).

I don't understand that - what accelerates the bullet is pressure. The more rapid the acceleration, the higher the pressure you need to achieve it. To achieve full velocity anything like instantaneously would require enormous pressure, and that would blow up the gun.

Nolo
August 7, 2007, 12:19 PM
You are, but you aren't doing it gradually, is what I mean.
Sorry for the confusion.

Monkeybear
August 11, 2007, 01:25 AM
Very interesting thread. Its good to see people out there trying new things and trying to solve problems themselves.


I was also going to shorten up the case so that there wasn't as much of it and so that the weight would be lower ('cause it's all just dead space).

I have a little experience with reloading and and I was a bit alarmed by this statement. The .357 Magnum revolver round, after you have charged it with with powder and depending on your load, can have about half of the case empty. When you insert your bullet into the case you have to be careful and maintain your Over All Length because if your OAL is too small it means that the bullet is seated too deeply. The resultant increase in pressure can be very dangerous. The increase in pressure is caused by the decrease in case volume caused by your bullet seating depth. I'm sure its a slower burning powder your talking about for your rifle round but my point is simply- case volume doesn't just mean how much powder you can fit. Perhaps, if you have not already, you should read a few reloading manuals and spend some time on the reloading forum if you are going to design your own ammo. Anyone; please correct me if I am wrong.

Also I notice that you tend to quickly gloss over very complex problems.



And, yes, the internal mechanism was complex, but I think you could simplify it significantly if you redesigned the weapon.



Simplify it how? Redesign it how? I understand that this the purpose of this thread is not to debate the design of various rifles but as this statement was made as a rebuttal to the argument that rifles using case-less ammunition were overly complex I think you should either conceded the fact that they are extremely complex or qualify your rebuttal. I am sure anything can be improved if done differently but the trick is in "How?".


Telescoping solves the problem of pressure. Basically they made the powder burn slightly slower so that it would expand using part of the barrel as the chamber, thus creating enough of a space to not have high pressures. By the time the bullet exits the barrel, it's doing 3100 f/s, and the "delay" is miniscule as to be not noticeable.


Statements like this sound good but once again the interesting part is- "How?". Cars work by exploding gasoline mixed with air in an engine to produce power that turns wheels. Sounds good enough to most people but if thats the extent of your knowledge, your not really qualified to build a better car.

I'm not trying to bust your chops so please excuse any rough language. I like your zeal and willingness to learn but I think your starting to run before you can walk. i know you are young and don't have access to a large amount of resources but get some some books on reloading, physics, design, strength of materials, anything along those lines. Used bookstores and used books on Amazon are your friends. Start actually making bullets from proven designs, and working with those. Take lots of math/science courses until you graduate highschool and take as many as you can in college. Don't stop playing and tooling around with ideas, thats the fun part, but don't forget the math and science of "Why?" is the hard part.

Nolo
August 11, 2007, 02:10 AM
Thanks, Monkeybear.
Yes, I know I'm jumping the gun. I always have. I look back at designs I did literally weeks ago and I know they they won't work, or they won't work as I want them to. I can't really help it. I try and redesign everything. I'm not sure where you got my first quote from, but I think it was from much earlier in the thread, and probably from an obsolete design. Oh well. It still applies, and you are still right.

Yes, I can gloss over complex problems, but I come back to them eventually. Sure, if I decided with the thread to go the caseless route (which I didn't), I would redesign the G11, internals and all. I looked at the insides and the basic operation and I said "there's got to be a better way to do that". Whether there is or not, I don't know, and, if I cared about it right now, I'd be spending most of my time trying to figure out that better way.

How does telescoping work? The pin strikes the primer. The primer lights a fast burning powder that pushes the bullet and some of the powder down the barrel far enough so that pressures will be acceptable. Then the rest of the powder ignites pushing the bullet out of the barrel at high speed. The Army is actually looking at a telescoping MG design right now.

Tony Williams
August 11, 2007, 04:08 AM
Nolo said: How does telescoping work? The pin strikes the primer. The primer lights a fast burning powder that pushes the bullet and some of the powder down the barrel far enough so that pressures will be acceptable. Then the rest of the powder ignites pushing the bullet out of the barrel at high speed. The Army is actually looking at a telescoping MG design right now.

Correct, but that isn't going to change the relationship between pressure and velocity by comparison with conventional ammunition. All it does is enable telescoped ammunition to be made more compact than conventional ammo of the same performance.

Nolo
August 11, 2007, 10:19 AM
Sure it doesn't. The reason that you don't need as much powder in the Knox rounds is because they use a more efficient (i.e. produces more gas per gram of powder), slower burning powder. I see nothing particularly special about smokeless powder, and I see no reason why someone couldn't improve on it, and, apparently, someone did.

jkingrph
August 11, 2007, 10:39 AM
Why reinvent, Look at the 6.5 Swede.

Nolo
August 11, 2007, 01:48 PM
Why reinvent? Because I can. Anyway, the rounds that I've come up with are far superior to the Swede, as well as most other rounds currently being fielded.
That is, of course, provided that they work.

Tony Williams
August 11, 2007, 04:10 PM
Sure it doesn't.
I'm not sure whether you're agreeing with me or not :confused:

The reason that you don't need as much powder in the Knox rounds is because they use a more efficient (i.e. produces more gas per gram of powder), slower burning powder. I see nothing particularly special about smokeless powder, and I see no reason why someone couldn't improve on it, and, apparently, someone did.
Certainly better powder can be invented. But the point I was making is that to achieve a given velocity with a given bullet, you need the same total "push" behind the bullet to get it up to that velocity. And that "push" is pressure. This is basic physics: the pressure curve can be altered, but the total "push" has to be the same.

If powder is tightly compressed, the pressure goes up. Conventional ammo has plenty of air spaces between the grains (even if the case is full), which gives some expansion room. Ammo for telescoped rounds is often finer grained and packed more tightly, so it uses a lot less space. This would normally cause an unacceptable increase in pressure, but the fact that the bullet is kicked up into the barrel by a smaller charge first provides that expansion room to keep the pressure in check.

Nolo
August 11, 2007, 04:16 PM
I'm agreeing with you.
What you said is absolutely true, the only difference with the Knox rounds is that their powders are more efficient, that's all. So, not only are they saving space by telescoping, they're saving space by having a more efficient powder.

Jason_G
August 11, 2007, 05:14 PM
This might sound a little odd, but honestly I can't see why a steel core version of the 6mm Remington wouldn't be a good choice. It's flatter shooting than the 5.56 NATO, with ballistics very similar to the 6.8 SPC. It also has the same mass as the SPC, but would be a little better in terms of penetration due to the smaller diameter. Put a steel AP core in it and you would have a good combat round with little recoil, light weight, and more umph than the 5.56.

Jason

Nolo
August 11, 2007, 05:58 PM
It's the weight, Jason. I'm guessing the 6mm Remington pushes a 100-grain-ish bullet down at 3000-ish f/s. That'll give you about 2000 ft-lbs, and, in a package the size of 6mm Remington, I'm estimating about 50000 EPP, which is no better than 5.56. Sure, it's performance is better than 5.56, so it's technically a better choice, but we can do better. See my 6mm carts.

Jason_G
August 12, 2007, 04:07 PM
It's the weight, Jason. I'm guessing the 6mm Remington pushes a 100-grain-ish bullet down at 3000-ish f/s. That'll give you about 2000 ft-lbs, and, in a package the size of 6mm Remington, I'm estimating about 50000 EPP, which is no better than 5.56. Sure, it's performance is better than 5.56, so it's technically a better choice, but we can do better. See my 6mm carts.
It ain't that heavy. Not a whole lot more than the 5.56 really. Anyway, I think at best EPP and EPM are fairly useless stats. At worst they are downright misleading. I think individual round performance (short range, long range, and terminal ballistics) vs. overall weight are what would be wisest to look at, especially for the rifleman's role. A soldier in the field isn't going to give a rat's ___ as to how much potential energy is stored in his mags. He's just wanting the bullet to go where it's supposed to go and kill what it's supposed to kill, none of which are ultimately dependent on the amount of energy present, although it doesn't hurt. If each bullet can do its job effectively, you don't need as many rounds, and EPM and EPP just don't matter. Also, the 6mm could be loaded hotter than civilian factory loadings, which currently push it at about 3100 fps, and the longer caseneck could accept a wider variety of bullets. There may be better choices out there, but I think it would definitely be a huge step up from the 5.56 NATO. Just MHO.

Jason

GunTech
August 12, 2007, 04:56 PM
Anteater1717,

7.62x45 is a case I had forgotten about, but it might be a good base. I necked the Czech round down to 6.7, and it falls nicely between 6.6 grendel and my 6.5x45mm based on a lengthed 6.5 PPC case. Assuming brass is available, here;s what the round looks like.


Cartridge : 6.5 x 45 Czech
Bullet : .264, 108, Lapua Scenar GB464
Cartridge O.A.L. L6: 2.362 inch or 60.00 mm
Barrel Length : 20.0 inch or 508.0 mm
Powder : Winchester 748

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.735% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-07.4 87 28.72 2442 1430 40631 7437 95.9 1.185
-06.6 88 28.95 2461 1452 41603 7492 96.2 1.172
-05.9 88 29.18 2480 1475 42600 7546 96.5 1.160
-05.1 89 29.40 2499 1497 43621 7599 96.8 1.147
-04.4 90 29.63 2517 1520 44669 7650 97.1 1.135
-03.7 90 29.86 2536 1543 45743 7699 97.3 1.124
-02.9 91 30.09 2555 1565 46845 7747 97.6 1.112
-02.2 92 30.32 2574 1589 47976 7793 97.8 1.100
-01.5 92 30.54 2593 1612 49136 7837 98.1 1.089
-00.7 93 30.77 2611 1635 50310 7880 98.3 1.078
+00.0 94 31.00 2630 1659 51547 7921 98.5 1.066
+00.7 94 31.23 2649 1682 52801 7961 98.7 1.055
+01.5 95 31.46 2667 1706 54087 7999 98.8 1.045 ! Near Maximum !
+02.2 96 31.68 2686 1730 55408 8035 99.0 1.034 ! Near Maximum !
+02.9 97 31.91 2704 1754 56765 8069 99.2 1.023 ! Near Maximum !
+03.7 97 32.14 2723 1778 58156 8101 99.3 1.013 ! Near Maximum !

Nolo
September 20, 2007, 06:31 PM
It ain't that heavy. Not a whole lot more than the 5.56 really. Anyway, I think at best EPP and EPM are fairly useless stats. At worst they are downright misleading. I think individual round performance (short range, long range, and terminal ballistics) vs. overall weight are what would be wisest to look at, especially for the rifleman's role. A soldier in the field isn't going to give a rat's ___ as to how much potential energy is stored in his mags. He's just wanting the bullet to go where it's supposed to go and kill what it's supposed to kill, none of which are ultimately dependent on the amount of energy present, although it doesn't hurt. If each bullet can do its job effectively, you don't need as many rounds, and EPM and EPP just don't matter. Also, the 6mm could be loaded hotter than civilian factory loadings, which currently push it at about 3100 fps, and the longer caseneck could accept a wider variety of bullets. There may be better choices out there, but I think it would definitely be a huge step up from the 5.56 NATO. Just MHO.
They really aren't useless. EPP and TME are useful because they tell you, in simple ratings, how much basic stopping power (One of the things that is important to the urban infantryman) is in every pound (the other thing he's worried about, i.e. weight) of ordinance he is carrying. It's efficiency. If you could do exactly the same thing that 6mm Remington does in a package that's half as heavy, would you? Absolutely. Is 6mm Remington better than 5.56? In my opinion, yes. Is it the best we can do? I think not. Now, is foot-pounds energy the end-all and be-all of stopping power? No, but if you do things (in otherwords, bullet design) right, then you can effectively make it a marker for stopping power. The most energy-efficient bullet out there is a hollowpoint. Now, the U.S. military can't use hollowpoints (would that they could!), so we have to find another way, or disguise them very well. :evil: That's what I plan to do with all of my bullets, and so I can use EPP as and effective short-range rating. You are correct that the EPP rating disintegrates at long ranges. That's okay, because I plan to make up for that with high velocities (which help the EPP anyway, because you are using the light powder instead of the heavy bullet to create energy) and really awesome BCs.

An update on what rounds I am currently attached to (all of them use Knox powder):
http://i200.photobucket.com/albums/aa149/Nolo_photo/5.56mmFirebrandEpsilon.jpg
I call this round the 5.56x39mm Firebrand Epsilon (as it is the 5th [E] in the series of 5.56mm designs). It pushes a 90-grain bullet at 3550 f/s, and is within the 5.56 NATO OAL. It also has recoil slightly higher than the 7.62x39mm and produces 2500 ft-lbs energy. Would make a great overall standard round, as it is quite capable as a DMR cartridge, an MG cartridge, a SAW cartridge and an assault rifle/carbine cartridge.
http://i200.photobucket.com/albums/aa149/Nolo_photo/6mmFirebrandGamma.jpg
Not sure if I've put this one up before, it's the 6mm Firebrand Gamma, a 110-grainer doing 2,900 f/s for 2000 ft-lbs.
http://i200.photobucket.com/albums/aa149/Nolo_photo/5.56mmFirebrandDelta.jpg
This is the 5.56x28mm Firebrand Delta. It does 3,000 f/s with a 90-grain bullet. It also has the advantage of being able to use a through-the-grip magazine.

GunTech
September 20, 2007, 08:19 PM
Telecoping rounds are nothing new. In modern ammunition they date back to at least the 1940s and the Hughes Chicklet. They are a change in form factor, nothing more.

I am extremely suspicious of any claims of more efficient powders. Generating more gas from a small amount of propellant buys you exactly nothing. It is the volume of the gas in the case. If you have a powder that reuires less volume and put it in a smaller case, pressure shoots up.

The only way to increase velocity without increasing peak pressure is to extend the working pressure over a longer period of time. This has proved to be extremely hard to do with propellants alone. It can easilt done by electrotherm (ET) and electromtheral chemical (ETC) protellants, but this has not proved practical in small arms.

Basically, you can compromise. You still have to deal with pressure, velocity, size and recoil no matter what. There is no magical solution that will give you the perfect round.

Nolo
September 20, 2007, 09:03 PM
Even if the Knox powders aren't truthful, I'm sure one can do it somehow.
Maybe even me. :D
I see no reason why you couldn't use the telescoping ammunition to reduce the pressure of the round. You use a small, efficient powder charge and then telescope it to reduce the pressure.

GunTech
September 21, 2007, 12:28 AM
Unfortunately, it doesn't work that way. The bullet doesn't start to move until the pressure is fairly high, and the pressure wave moves faster than the bullet can (propellant gas expands at at leat 4000 fps, any can be as high as 6,000 fps). You might be able to do something with a sabot which had a low coefficient of friction and a fairly large area, however this concept has been around since before WWII and hasn't met with any success to date. If you look at the time/pressure curve of typical propellants, it easy to see why. Most of the propellant burns before the bullet has even left the cartridge.

Nolo
September 21, 2007, 09:19 AM
:scrutiny:
It's not that you are incorrect, it's just that I don't see why. I get that you need pressure to push something fast. That's a "duh" for me. But by what you said as I understand it, you could never push something past a certain speed, no matter what powder and case capacity you had. I know it is impractical to push a bullet faster than about 5,500 f/s, but that's not the speed I'm looking for.

Rifleman 173
October 6, 2007, 10:38 PM
Having been in combat, one thing that most ammo designers FAIL to understand is that American soliders and marines will, sooner or later, be going up against enemy forces who use narcotics/drugs to DELIBERATELY offset the effects of our shots. In Nam we sometimes faced communist troops that were stoned to the gills with opium or heroin in them. In Mogodishu (Black Hawk down) it was suspected that the troops that attacked the Americans there used very strong hashish possibly laced with something like opium. Your minimum bullet weight should be 120 grains and more would be better. Your minimum bullet diameter should be 7.62/.30 caliber. The length of the bullet should be more like a spear (long, heavy & thin) than a dart (short & light). The bullet should have good velocity to give it punch and accuracy. You do not need to have a 30 round magazine. If you design your ammo right, you can use 25 round magazines instead. Your firearm should be "modular" in design sort of like a FN/FAL, Steyr AUG or good AR-15/M-4. My suggestion would be to have each weapon come with a system of changeable uppers so that the user could switch upper halves from rifle to carbine to light machinegun (heavy barrel) depending upon desired use OR design it to be like a light machinegun with a selector switch to allow the shooter to also use it as a rifle. Sort of like the combination machinegun/rifle that the old German paratroopers had in WW2. They loved their firearm. Also do NOT try to re-design the AK-47 (7.62 X 39) cartridge. Come up with something new that uses new technology and new chemistry. If you meet all of these suggested ideas, you WILL make a large number of people happy.

rangerruck
October 6, 2007, 11:54 PM
Basically , the round you have in mind allready has been round long time. 5.6 x52. Also known as the savage hipower. shoots an 80 grain bullet at 3400 fps from a 24 inch bbl. slender cartridge, light, can carry a bunch , can belt feed no problems, nice long necks. If we dont' wanna do this, the the old 6mm remmy would do all the above, even easier, with 95 grain fmjs or power points. superlong necks for better bbl life, easier on the wear and tear, smoothly tapered cartridge. 600 yard shots, and knock over a deer like it has been struck by lightning.

Nolo
October 7, 2007, 02:14 AM
Having been in combat, one thing that most ammo designers FAIL to understand is that American soliders and marines will, sooner or later, be going up against enemy forces who use narcotics/drugs to DELIBERATELY offset the effects of our shots.
You're absolutely right. Which is exactly why I'm trying to design a round that incapacitates the enemy as quickly as possible. The real way to do that is by opening up as many arteries and veins as possible in the target. I think fragmentation is the key here.

Your minimum bullet weight should be 120 grains and more would be better. Your minimum bullet diameter should be 7.62/.30 caliber. The length of the bullet should be more like a spear (long, heavy & thin) than a dart (short & light).
I hate to say it, but a 120-grain .30-caliber bullet is not going to be shaped like spear. It will be shaped like dart (short & light). Heavy and thin would be a 120-grain 6.5mm, a 105-grain 5.56mm or a 90-grain 4.7mm. I don't want to go all the way down to 4.7mm, so I'm going with a 90-grain 5.56mm round. Much heavier than our current round, the same standard caliber and the bullet goes as fast.
You do not need to have a 30 round magazine Technically, you only need a single-shot weapon. But a 30-round mag is nice. I think that mags should be arranged with bullet power according to a logical table, like this:
-500-900 ft-lbs; 50 round mag
-1000-1400 ft-lbs; 40 round mag
-1500-1800 ft-lbs; 30 round mag
-1900-2500 ft-lbs; 20 round mag

Your firearm should be "modular" in design sort of like a FN/FAL, Steyr AUG or good AR-15/M-4
I agree. But this is about the rounds, not the rifle.

Also do NOT try to re-design the AK-47 (7.62 X 39) cartridge. Come up with something new that uses new technology and new chemistry.
Well, if you look at the redesign that I did for the 7.62x39 round, it did precisely what you suggested. When I designed that cartridge, I wasn't thinking about the 7.62x39mm cartridge at all. I actually was trying to apply Knox technology to a round that would push a 180-grain, .30 caliber bullet at 2800-2900 f/s. When I designed it, it was so similar in dimensions to the 7.62x39mm round that I decided to just use that case. You get the performance of a 7.62N in heavy loadings, a good 6mm cartridge (saboted) in lighter loadings, and you have the added benefit of being able to use captured ammo.

Basically , the round you have in mind allready has been round long time. 5.6 x52.
Performance-wise, maybe. But not exactly. See, unless 5.6x52 has an extremely thin (I suspect that it is about 9-10mm, which is far too large) case, which I doubt, then it is much heavier than the cartridges I am looking at. Soldiers care about weight. They care about the amount of ammunition they can carry before they become overburdened. My goal is partially to imporve performance, but it is more about reducing weight.

rangerruck
October 7, 2007, 03:46 AM
http://www.loaddata.com/images/database/ACFA3E.gif
http://accurateshooter.net/Diagrams/223remx330.gif

Nolo
October 7, 2007, 09:35 AM
That's bad for a couple of reasons. The .22 Savage high power appears to be rimmed, not a good fit for automatics. Second, it appears to be quite old (utilizing less advanced technology). Third, it's even larger than I expected it to be (12mm!). Fourth, if I were to fix all these problems and then improve on it, I'd end up with the cartridges I've already shown you.

GunTech
October 7, 2007, 12:57 PM
You don't want to make a conventional FMJ bullet long and thin. It won't tumble and fracture and yuou end up with the lethality of the Italian Carcano. Big bullets aren't necessarily good either. Remember that you are limited to FMJ by treaty. All of the 30 caliber bullets the US has used are very stable and tend to drill right through a target with little upset and distortion. It's owrht noting that in Vietnam, the 5.56x45mm M193 was actually shown to be 11% more lethal at combat ranges than the more powerful 7.62x51mm. The reason is simple - the M193 would tumble and fracture in tissue creating multiple submissiles. The 7.62x51 would pass straight through losing v=little velocity. This has all been covered in this thread previously.

With regard to a new cartridge, it is worth noting that there has been very little improvement in propellant technology in the last 100 years, so assuming there will be a great change is a false hope. What has change thing somewhat is new materials, and cartridges can be loaded to slightly higher pressures.

It is ultimately the total volume og gas produced in deflagration that will determine velocity. More powder produces more gas, but the more gas in a given case, the higher the peak pressure. Thus, you will have a larger case volume for a higher velocity for the same bullet.

Ultimately, there is no magic formula that will get you a super-cartridge. You have to make compromises. You can have a larger, fast projectile from a small cartridge at safe pressure. The 5.56x45 was a concious decision to limit range and power in exchange for more ammunition. If you don't think 5.56 has enough power, you can go up in caliber and you'll end up with a larger cartridge. Period.

Many here are basically arguing that therer exists a middle ground catridge that splits the difference. Rounds like the 6.8 SPC and 6.5 Grendel fall into this category. Are they clearly suoperior? Probably not. They just change the compromises. They may have more general utility than existing rounds, and thus be more approrpiate for more situations than existing rounds. You are never going to have a perfect round for every conceivable military scenario. Whay works very well in dense jungle may not be appropriate for open mountainous terrain. But perhaps there is a decent 'jack of all trades, master of none' round.

My own 6.5x45 was lterally a 'split the difference round'

5.56x45 62gn bullet
7.62x51 150gn bullet
Average 106gn

5.56 = 0.224
7.62 = 0.306
Average = 0.266 = 0.264 =6.5mm

M855 3000fps
M80 2850fps
Target velocity ~2925

So, a 106gn 6.5mm bullet at about 2900. And thus a catridge somewhere in zize between the 7.62x51 and the 5.56x45

Resulting in the 6.5x45

http://guntech.com/ammo/6.5x45.jpg

This cartridge, 'on paper', will throw a 107gn SMK at 2900fps with M16 safe pressures, or a 100gn FMJ at over 3000. If long range precision is needed, a 'special ball' analog to the M118LR could be created using a 123 or 139gn Scenar bullet that will compare vert favorably with the best 7.62x51 LR ammunition.

The downside's are that the rifle will have to be slightly larger - basically a M16 with a magazine that is 0.250 inches longer. The ammunition will be larger and heavier, thus fewer rounds could be carried - more than 7.62x51 but fewer than 5.56x45. Recoil would also be heavier than 5.56x45. Just slightly more than a 9 pound AK firing M43 ball.

As noted, it just a 'different' compromise.

GunTech
October 7, 2007, 01:14 PM
Nolo,

Here's my 5.7x45mm, which will toss a 62gn M855 bullet at a calculated 3395fps with normal M16 safe pressure. It will even fit in an existing M16 magazine. Based on the 7.62x45mm Czech with 5.56x45 shoulder (23 degrees) and a slightly more tapered case (30 minutes 30 seconds).

It's only 100 fps slower than a 22-50 and can be fired from an AR-15.

http://guntech.com/ammo/5.7x45.jpg

HorseSoldier
October 7, 2007, 01:18 PM
Trying to tailor rounds to stop people on drugs is kind of pointless. It happens occasionally, but is one of those things highly mythologized and exagerrated (especially by those who find real world bullet performance in any caliber to not match their Hollywood fueled expectations, etc.).

And when people are in some altered state of conciousness due to drugs you get a declining benefit trying to make the bullet do the work. Central nervous system hits work regardless of caliber, and anything else is uncertain if drugs (or more commonly adrenalin surge) are letting someone shrug off injuries. The training to put the bullets where it matters and the mindset to recognize that you're going to kill someone and if one bullet doesn't do the job you need to continue attacking, continue shooting, and put someone on the ground dying are worth more than some special junkie-busting bullet.

Slugless
October 7, 2007, 01:59 PM
I admit to not having read this entire thread but skimming for the more interesting bits...

Nolo, have you been looking into terminal effects of bullets? I saw you mention fragmentation to open up vein & arteries, but it's a bit more complex than that.

My understanding - it's common for weapons designers to start with the bullet, then go to the casing, and finally the rifle. The bullet is designed for certain terminal characteristics, such as:

crushing, which produces a permanent cavity
stretching of tissue producing a temporary cavity

That's really it. Since a hollowpoint is out of the question (I'm not sure what you mean by "that's what I plan to do with all of my bullets"), the bullet must be designed to tumble at all effective ranges. The AK74 projectile has a 5mm long air space in the tip to move the CG back towards the tail so it tumbles very effectively, a little sooner than ours. Tumbling should start very early, 10 cm or so. Fragmentation is great but given our experience with the 5.56 rounds fragmentation should not be counted on but it sure is a plus. The Russians could have done that but their round appears to be designed for two tumbles while in flesh. I don't know what the 5.56 does w.r.t. tumbling if it doesn't fragment.

I've not looked at the pretty pics of ballistic gel tests, my reference is Emergency War Surgery, a NATO handbook, 1988 ed. The surgeons know what kills and incapacitates.

I think you'd like this book very interesting. Let us know what the school librarian thinks when you ask for it inter-library loan! "It's for a biology class project, ma'am"

Anyone have a good link to gel tests?

HorseSoldier, I hear you & know what you mean but I recently spoke with a Marine who fought in Fallujah and they were clamoring for a more effective round because their opponents were high. They found some opponents "on the ground dying" who turned into "ghosts" and had to be re-shot. Hence the Kevin Site's video. Pointless to tailor rounds to stop people on drugs? Where did the development of the .45APC come from? It was certainly a perception before.

Food for thought.

GunTech
October 7, 2007, 02:03 PM
Great post HorseSoldier.

It's also worth considering that there are people walking around who've been hit with 50 caliber mahineguns, cannon and even RPG rounds. If you look at polive files, there are plenty of examples of druggged up criminals absorbine insane amounts of damage and continuing to fuction. No round short of somrthing that blow a person into chuncks is going to be 100% effective.

One of the issues brought up in the Somoalia conflict is that the Somalis had so little muscle mass that round typically went right through before tumbling or breaking up. I'm not sure how you address that.

Nolo
October 7, 2007, 04:19 PM
GunTech, I like your 6.5mm cart, but I don't think I understand your hesitation to utilize new technology. If we were to try old technology, we all know what would happen, we'd basically end up with a longer 6.5 Grendel. Which is roughly what you have there. That's fine, and would be an excellent round, but it doesn't improve on anything, really. I understand that a long bullet is less likely to fragment, but if you use proper bullet construction, I think you can mitigate this and get both superior long-range performance and terminal performance.
It is ultimately the total volume of gas produced in deflagration that will determine velocity. More powder produces more gas, but the more gas in a given case, the higher the peak pressure. Thus, you will have a larger case volume for a higher velocity for the same bullet.
You are correct but in one word: case. It is not case volume that is greater for higher velocities, it is chamber volume. This is important. It is true that my cases are far to small to adequately contain the pressures that my cartridges produce. However, my rounds have a larger chamber than most cartridges, i.e., they use part of the barrel for the chamber, which should (but nothing is ever proven until it's tested to death) reduce the pressures to acceptable levels.
Ultimately, there is no magic formula that will get you a super-cartridge. You have to make compromises.
You are right, but technology can be improved and, quite frankly, I think we are due for a change. I mean, people tried to balance most of the same things that we did back in the late 1800s and they eventually reached the level that they reached. Then Mauser came out with his spitzer bullets and suddenly rounds just got better. That happens sometimes. I hope it happens (or has happened) soon.
Trying to tailor rounds to stop people on drugs is kind of pointless. It happens occasionally, but is one of those things highly mythologized and exaggerated (especially by those who find real world bullet performance in any caliber to not match their Hollywood fueled expectations, etc.).
True, but there's no problem in trying to tailor rounds to kill people faster. If it will kill a druggie faster, it will kill a regular person faster. Drug addicts seem to be the acid test.
Since a hollowpoint is out of the question
Who says? The Hague Convention? Since this is pretty much a pen-and-paper exercise anyway, why do we need to worry about stupid laws? Okay, if you want to make a cartridge that fits with the HC, then fine. I think you'll find that that's a simple bullet design change. I don't think it really changes the cartridge any. Not the direction I'm going, anyway.
(I'm not sure what you mean by "that's what I plan to do with all of my bullets")
I mean that I think all of my cartridges are going to use a frangible-AP bullet.
The AK74 projectile has a 5mm long air space in the tip to move the CG back towards the tail so it tumbles very effectively, a little sooner than ours. Tumbling should start very early, 10 cm or so. Fragmentation is great but given our experience with the 5.56 rounds fragmentation should not be counted on but it sure is a plus.
As far as I know, tumbling and fragging are pretty much equally reliable. You can make them more reliable (like the 5N7 bullet or frangible bullets), but as far as normal bullets are concerned, I believe that both fragmentation and tumbling are relatively equally reliable.

GunTech
October 7, 2007, 04:45 PM
Nolo,

Telescoped rounds have been tried in the past. They don't reduce chamber pressure. It's a nice concept but it doesn't work. The pressure rise time is too fast. 90% of peak pressure is reached typicaly before the bullet has even started to move, so the idea of using the barrel as part of the chamber doesn't work to reduce peak chamber pressure. If it did, conventional rounds would benefit the same way.

Sorry.

If you rteally want to gain velocity without peak pressure probklems, you need to find a way to flatten the time pressure curve they way they do in CAP, ETC and ET guns. But iun that case, you can vary the current delivered to the working fluid via electronic control. That's not an optiom in a purely chemical combustion system. You can control burn rate and pressure curve through propellant composition, grain geometry and retardants, but that only helps a little.

Nolo
October 7, 2007, 04:53 PM
Telescoped rounds have been tried in the past. They don't reduce chamber pressure. It's a nice concept but it doesn't work. The pressure rise time is too fast. 90% of peak pressure is reached typically before the bullet has even started to move, so the idea of using the barrel as part of the chamber doesn't work to reduce peak chamber pressure. If it did, conventional rounds would benefit the same way.
I know, with modern powders that is true. But if you used a powder that burned slower and more efficiently, then it would work. I don't think I'm missing anything there.
If you really want to gain velocity without peak pressure problems, you need to find a way to flatten the time pressure curve they way they do in CAP, ETC and ET guns. But in that case, you can vary the current delivered to the working fluid via electronic control. That's not an option in a purely chemical combustion system. You can control burn rate and pressure curve through propellant composition, grain geometry and retardants, but that only helps a little.
I don't see why using slower-burning powders and composite powders wouldn't make a significant difference. I think you could engineer it to work. And, if you did, the benefits would be enormous. You could carry half again as much ammunition with better ballistics and a smaller weapon.

Nolo
October 7, 2007, 04:55 PM
Hey, GunTech, what would it look like to neck up the 6.5x45mm GT to 6.8mm with a 123-grain bullet?

Slugless
October 7, 2007, 05:16 PM
Nolo,

Fair enough, your round, you can make it "illegal" if you want. (I love hearing euro-weenies talking about the law of war as if it were traffic regulation)

According to the bible w.r.t M-193, "The degree of bullet fragmentation decreases with increasing shooting distance, as striking velocity decreases. At a distance of 80 meters, the bullet breaks in half, forming two large fragments. At ranges in excess of 180 meters, this projectile does not break in two and the wounding capacity and mechanisms are essentially the same as those of the AK-74."

Are frangible and AP compatible? It will tumble, fly into little pieces at the first touch of soft tissue and yet defeat modern body armor? Will it dance and sing, too? ;) Note that the steel core ammo we use is not armor piercing.

And no, frangible and tumbling are not equally effective. Read the book. If you mean equally reliable, it's your bullet.

I often thank people who I believe are offering constructive comments. The last time I was almost dismissive of someone here on THR he came back with another comment that allowed me to solve the problem

Nolo
October 7, 2007, 05:23 PM
I often thank people who I believe are offering constructive comments. The last time I was almost dismissive of someone here on THR he came back with another comment that allowed me to solve the problem
I'm not sure what this means... :uhoh:
According to the bible w.r.t M-193, "The degree of bullet fragmentation decreases with increasing shooting distance, as striking velocity decreases. At a distance of 80 meters, the bullet breaks in half, forming two large fragments. At ranges in excess of 180 meters, this projectile does not break in two and the wounding capacity and mechanisms are essentially the same as those of the AK-74."
That's true. But the M193 wasn't designed for fragmentation (or, at least, it was HC compliant, which is almost the same thing :rolleyes:). If you made a bullet that was easily torn apart, I think you would find a very different result.
Are frangible and AP compatible? It will tumble, fly into little pieces at the first touch of soft tissue and yet defeat modern body armor? Will it dance and sing, too? Note that the steel core ammo we use is not armor piercing.
Yes. They are. I think it was Bugger and Thomet who created a round that had a Hollopoint jacket around an armor piercing core for a PDW-type weapon. This is the same concept. The frangible outside will not defeat body armor and the tungsten core will not fracture in tissue. But both will do their thing and that's a good compromise between frangibility and penetration.

Slugless
October 7, 2007, 05:27 PM
I was attempting to point out that it's not a good idea to be dismissive of people trying to help you. They may have information and experience you don't.

For example, the M-193 was designed to be frangible. It was made to be easily torn apart.

Nolo
October 7, 2007, 05:41 PM
I was attempting to point out that it's not a good idea to be dismissive of people trying to help you. They may have information and experience you don't.

For example, the M-193 was designed to be frangible. It was made to be easily torn apart.
I'm not dismissing you. You have knowledge and you are sharing it with me. I appreciate that. I thank you for that, but I also see flaws in you arguments. The M193 was designed to be frangible within the parameters of the Hague Convention, which severely restrict that property of terminal damage. For instance, the M193 has no facility (by breaks, gaps or other structural compromisers) for breakage of the copper jacket. If you were to cut a cross- or star-shape in the tip of the bullet of an M193, you would find that it would fragment much more easily, that's why hollowpoints are designed with such facilities. The 5N7 bullet has no such legal restrictions on its ability to tumble in the body. It's like comparing the HK SL8 to the SIG 550 and then asking which is the better assault rifle. Well, of course the 550 is, but that's only because the SL8 has all these restrictions placed upon it. A better comparison would be the G36 to the 550, because they are both relatively unrestricted by legality.

GunTech
October 7, 2007, 07:15 PM
I don't see why using slower-burning powders and composite powders wouldn't make a significant difference. I think you could engineer it to work. And, if you did, the benefits would be enormous. You could carry half again as much ammunition with better ballistics and a smaller weapon.

If you could, they'd already be doing it.

GunTech
October 7, 2007, 07:27 PM
The fact that the M193 breaks up is pure serendipity. Stoner designed the rounds by scaling down a 308 caliber bullet. The fact that it fragments in tissue wasn't reported widely until many years after the M193 was in service. Dr M. Fackler is generally regarded as the first person to publish extensively on why the M193 is effective, after the Army discovered that statistically the M193 was 11% more lethal than the M80. In the jungles of Vietnam, the majority of combat was meeting engagements and ambushes - perfect environment for the 5.56x45 as these general occured at relatively short range.

Fast forward to the 1980, and the SS109. It was originally championed by the Swede's and other Europeans as being less nasty than the American M193 (See "Anti-personnel Weapons" published by the Stokholm International Peace Research Institute, or SIPRI). Europeans were slowly following the US lead to 5.56x45 from 7.62x51 but were conserned by the 'inhumane' wounds created by the M193. The US adopted the SS109 to the M855, more concerned with long range performance in the SAW than its more humane wounding. The 6x45mm SAW was dead and a simple replacement was needed. Again, engineer added a very deep canneleur, plus a penetrator, that led to a projectile that was unstable in tissue and tended to fragment. Nothing in the developmental work on the M855 suggests that fragmentation was a desired characteristic that was designed in. It was again, just serendipity.

It is in fact rather easy to make an FMJ bullet fragment catastrophicly if you follow a couple of rules: Use a thin jacket. Use a deep canneleur. And make it relatively base heavy. In fact, the germans developed a 7.82x51mm cartridge that behaved exactly like the M193 and M885 bullets in tissue, but it was never issues in quantity. All of these rounds meet the letter of the Hague conventions, while being much more lethal than more conventional analogs.

Nolo
October 7, 2007, 07:28 PM
Really? The British could have switched over to a semiautomatic rimless-cased rifle in the '20s or '30s, but they kept the SMLEs until the '50s. The United States military could have switched from a muzzle-loading weapon to a breech-loading weapon in the 1850s and '60s, but we didn't. There are various reasons why technologies are or aren't adopted, so one can't simply explain away things by saying "if it was doable, we'd be doing it". In fact, the US military is looking into a cased, telescoping SAW that reduces the weight of the 5.56 cartridge by about 33%. It's in testing I believe. Don't recall its name, though... I want to say that it's a version of the Ultimax 100 or somesuch.

Nolo
October 7, 2007, 07:30 PM
GunTech, you rock. Knowrage is powah. :D

GunTech
October 7, 2007, 07:40 PM
It should be noted that most rounds that use an embedded penetrator aren't very lethal. Combinations tend to be pretty poor at both jobs. Imbed a pentrator in a 223 bullet and you end up with something under 20 caliber and probablt 30 grain.

The Eupeans have a different idea of lethality. They consider the 5.7x28mm a reasonable combat round. That's a round that is basically a glorified 22 WMR. Interdynamics was actually working on a rifle that would be very close to the 17HMR in performance. Many Americans consider the 5.56 woefully underpowered.

GunTech
October 7, 2007, 07:48 PM
Not militaries, but commercial producers. Militaries are very conservative, but if one of the big commercial powder manufacturers could imporve significantly over what's offered, they'd jump on it like a shot because plenty of people (like me) would gladly pay for it.

There have been imporvements over time, but these are generally minor and sometimes have other effects. Vihtavuori Oy for example has a range of powders, their 500 seried, that generate higher velocitis with the same pressures by using double base propellants with a higher proportion of nitroglycerine. However, there are indications that these powders are less stable in long term storage and more temperature sensitive.

The kind of improvements you are positing would be worth a lot of money on the xommercial market, particularly as there is now little to distinguish one brand over the other.

GunTech
October 7, 2007, 07:57 PM
BTW, re 6.8 in the 6.5x45. I haven't run the numbers, but I did look at what you would get if you used 7.62x45 as the basis iof the 6.8SPC instead of the 30 Remington. With the same shoulder angle and body taper, but the slightly larger case head, you gain an easy 150 fps in velocity. I expect that using the unshortened 7.62x45 necked down to 6.8, you gain at least another 150 fps.

I still prefer the 6.5 bullet for its better sectional density, but as noted, the 6.5 lacks a decent FMJ bullet that compares favorably with the 6.8. But The 6.5 seems to be more flexible. Stuff a 100gn bullet it it, and you get 3000 fps easily, a 40% gain in energy over the 5.56x45mm. Using a high BC 123gn bullet, you have enough retained energy to make the same cartridge lethal at over 1000 yards.

The 6.5 also has better potential as a hunting round. However, any of these require a new weapon, unlike 6.8 and 6.5 Grendel.

Lately, I have been playing with my 5.7x45mm. It looks like you can get very close to 22-250 ballistics (within 100 fps) from the AR-15 platform. You could drive a M855 at 3400 fps with reasonable pressure, which might be interesting.

But I don't see 5.7x45mm as a combat round - strictly as a varmint cartridge.

Nolo
October 7, 2007, 08:33 PM
GunTech, if an embedded penetrator sucks, then I'll just go to one AP version and one frangible version. Easy. As for the powder improvements, I believe that the US military is looking into an LMG using the very same technology that I am talking about. But what you say is true. Markets are fast and competitive. Militaries are slow and reluctant.
Fair enough about the 6.x by 45mm carts. That seems par for the course. Remington choose one direction, Alexander Arms chose another.
I could see a 90-grain 5.56 at ~3000 f/s as a combat cartridge, provided you had good fragmentation.

Slugless
October 7, 2007, 08:52 PM
GunTech,

The fact that the M193 breaks up is pure serendipity. Stoner designed the rounds by scaling down a 308 caliber bullet. The fact that it fragments in tissue wasn't reported widely until many years after the M193 was in service. Dr M. Fackler is generally regarded as the first person to publish extensively on why the M193 is effective, after the Army discovered that statistically the M193 was 11% more lethal than the M80. In the jungles of Vietnam, the majority of combat was meeting engagements and ambushes - perfect environment for the 5.56x45 as these general occured at relatively short range.

I should have read my reference more carefully.

The large permanent cavity shown in the profile was observed by many surgeons who served in Vietnam, but the tissue disruption mechanism responsible was not clear until the importance of bullet fragmentation as a cause of tissue dispruption was worked out.

Tony Williams
October 7, 2007, 09:43 PM
One possible solution to the controlled pressure rise is to learn from rocket propellant technology (I have often wondered why this hasn't been done).

Produce a solid propellant which is cast into the case, with a hole down the length of it. When first ignited, the surface area of the inside of the hole would be small so not much gas would be generated. But as the propellant burns away, the hole gets bigger and the burning surface gets steadily larger, producing increasing quantities of gas. In theory, at least, that should result in a much more gradual pressure rise. It could also have the incidental benefit of keeping chamber temperatures lower, since the burning area wouldn't reach the case walls until right at the end of combustion.

Of course, it would require a different propellant chemistry and case filling technology, and you can forget about handloads, but I wouldn't have thought that would trouble the military too much.

HorseSoldier
October 7, 2007, 09:54 PM
The M193 was designed to be frangible within the parameters of the Hague Convention, which severely restrict that property of terminal damage. For instance, the M193 has no facility (by breaks, gaps or other structural compromisers) for breakage of the copper jacket. If you were to cut a cross- or star-shape in the tip of the bullet of an M193, you would find that it would fragment much more easily, that's why hollowpoints are designed with such facilities. The 5N7 bullet has no such legal restrictions on its ability to tumble in the body.

I believe the Soviets considered the 5.45x39 round to be Hague compliant. As did the Germans, who deliberately built their 7.62x51 ammunition with a thin jacket and deep cannelure to fragment like M193.

Military bullet design is really tap dancing in a grey area, legally speaking, because the Hague Convention does not limit its restriction to hollow point ammunition -- it rules out the use of any round designed to increase suffering or (for all intents and purposes) enhance lethality over that achieved with an FMJ round. So, if you build a bullet with enhanced lethality features, there is no way it can truly be Hague compliant.

However, the world's militaries seem to have basically agreed to ignore the Hague Convention if the round has a full metal jacket wrapped around it and it's enhanced performance over FMJ is not so significant, or its development so blatant, as to make the polite fiction break down.

Very much getting into a Catch-22 sort of realm.

That said, the other thing to bear in mind is that there are valid reasons why you don't want a round optimized for anti-personnel use, however it achieves that performance. Barrier penetration specifically comes to mind as something that also needs to be taken into consideration. This is the main argument I see against Mk 262 5.56mm ammo -- terminal ballistics are great, but it gives up barrier penetration (something modern assault rifle rounds are already not great at) compared to M855. I feel like it would be a major issue with any round really optimized for fragmentation above and beyond what OTM rounds do.

Nolo
October 7, 2007, 10:20 PM
Which is kinda why I'm just ignoring the HC.
Oh, and Tony, that is an excellent idea.
I need to be able to test this stuff!

Nolo
October 8, 2007, 12:04 AM
Hey, GunTech, can you run the pressures for this cartridge:
http://i200.photobucket.com/albums/aa149/Nolo_photo/6.5x47Firebrandmeasurements.jpg
6.5 Firebrand
-Muzzle Velocity: 2800 ft/s
-Bullet Weight: 123 gr.
This should be from a 20-inch barrel.
Thanks a million.

GunTech
October 8, 2007, 01:19 AM
Tony, interesting thought.

As many know, powder granules are designed so that the srface area remains the same (neutral), increase (progressive) or decreases (degressive). Building a giant 'grain' on could theoretically take advantage of progressive or degressive characteristics. The big question is if burning rates would be fast enough and uniform enough.

Another possible advantage would be the aility to do things like front ignition. If the charge is ignited on the side closes to the bullet base, you tend to get more velocity and more uniform burn.

Finally, with a solid 'propellant block' you could use different buring rates and control pressure through the cycle by having various layers that would flatten out the pressure time curve to better match the theoretic pressure curve of the barrel. You could hold a given pressure over a longer period of time, without exceeding the yield pressure, meaning much more velocity.

This was a huge advantage of ET and ETC rounds. In the late 1970's, Hughes demonstrated a modified M16 that could almost double the velocity of the standard weapon without exceeding the peak pressure of the standard round.

Of course one has to wonder why the smart guys in small arms development haven't done it yet. My suspicion is probably that the cost isn't worth the effort. Just looking over the issues with ETC, as well a liquid propellant guns, I'm betting it not as simple as one thinks. Liquid propellant artillery has huge theoretical advantages over conventional artillery, and yet despite reearch since WWII, not LP gun has been fielded.

The same can be said for caseless ammo. It has been done. The G11 was working as a preproduction firearm over 25 years ago and yet there's still no caseless weapons in in use. Sometimes the disadvantages aren't as obvious.

GunTech
October 8, 2007, 01:20 AM
Hey, GunTech, can you run the pressures for this cartridge:

I'll have to draw it up in QuickDesign, then run the numbers in QuickLoad. Give me a day or so.

Tony Williams
October 8, 2007, 02:05 AM
Finally, with a solid 'propellant block' you could use different buring rates and control pressure through the cycle by having various layers that would flatten out the pressure time curve to better match the theoretic pressure curve of the barrel. You could hold a given pressure over a longer period of time, without exceeding the yield pressure, meaning much more velocity.

Yep, that's what the rocket scientists do. They usually start with a fast-burning layer to get the missile up to speed, then follow with a slow-burning sustainer layer. Might be a bit complex for small arms, though.

Another approach they use is to vary the cross-sectional shape of the hole. If they want a fast-burning boost at the start, they can make a star-shaped rather than circular hole, which increases the initial surface area.

In principle, you can fine-tune the pressure curve any way that you want, without the complexity of ETC. That's why I can't understand why the military have, AFAIK, never tried this.

GunTech
October 8, 2007, 07:53 PM
Hey, GunTech, can you run the pressures for this cartridge:

The bad news is that to make 2800 with a 123gn 6.5mm bullet, you need 70,000 psi


Cartridge : 6.5 firebrand
Bullet : .264, 123, Sierra HPBT MatchK 1727
Cartridge O.A.L. L6: 2.689 inch or 68.30 mm
Barrel Length : 20.0 inch or 508.0 mm
Powder : Winchester 748

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.282% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-12.8 93 26.15 2342 1498 44310 7385 96.1 1.156
-11.5 94 26.54 2377 1543 46378 7486 96.6 1.133
-10.3 96 26.92 2411 1588 48552 7582 97.1 1.110
-09.0 97 27.31 2446 1634 50837 7672 97.6 1.087 ! Near Maximum !
-07.7 98 27.69 2481 1681 53245 7757 98.0 1.065 ! Near Maximum !
-06.4 100 28.08 2515 1728 55779 7837 98.4 1.044 ! Near Maximum !
-05.1 101 28.46 2550 1776 58450 7911 98.7 1.023 !DANGEROUS LOAD-DO NOT USE!
-03.8 103 28.85 2585 1824 61267 7978 99.0 1.003 !DANGEROUS LOAD-DO NOT USE!
-02.6 104 29.23 2619 1873 64241 8039 99.3 0.983 !DANGEROUS LOAD-DO NOT USE!
-01.3 105 29.62 2653 1923 67383 8094 99.5 0.964 !DANGEROUS LOAD-DO NOT USE!
+00.0 107 30.00 2688 1973 70705 8142 99.7 0.945 !DANGEROUS LOAD-DO NOT USE!
+01.3 108 30.38 2722 2024 74221 8182 99.8 0.926 !DANGEROUS LOAD-DO NOT USE!
+02.6 109 30.77 2756 2075 77946 8216 99.9 0.908 !DANGEROUS LOAD-DO NOT USE!
+03.8 111 31.15 2790 2127 81894 8242 100.0 0.891 !DANGEROUS LOAD-DO NOT USE!
+05.1 112 31.54 2824 2179 86087 8261 100.0 0.873 !DANGEROUS LOAD-DO NOT USE!
+06.4 113 31.92 2858 2231 90542 8276 100.0 0.856 !DANGEROUS LOAD-DO NOT USE!


However, you probably have more body taper than necessary.

Here's the cartridge as you gave it to me with a version 2, which will do 2600 fps with a PMax of 60,000 psi

http://guntech.com/ammo/6.5firebrand.jpg

The major issue is this is a totally new case. If you want something that is doable as a wildcat, you might want to look at existing cases that you can modify.

Tod

Nolo
October 8, 2007, 08:32 PM
I figured it would be high. I designed the round for Knox powders, but it was large enough that I thought it might get me there. But it didn't. Oh well. :D
Plus, it was designed for heavy weapons, anyway.
What if you used a 7.62x45 case? Oh, wait, that's just 6.5GT.
How fast will 6.5 GT send a 123-grain LS bullet out of a 20-inch barrel?

Nolo
November 18, 2007, 09:39 PM
I think I've settled on an 87-grain 5.56 at 2800 f/s from a 15.25-inch barrel:
http://i200.photobucket.com/albums/aa149/Nolo_photo/556Meteor.jpg
I'm optimizing it for a 15.25-inch barrel, as I think that is the length (the mean of 16 and 14.5) that is most appropriate.
I've named it 5.56 Meteor. The bullet is a high-frangibility bullet with a cross-shaped break in the cupro-nickel jacket on the tip, it's also highly streamlined, unlike the 77-grain Black Hills Mk. 262. I shortened the case to 43mm and took Tony's advice and went to a formed, solid propellant with a channel in the center.
I think this really is the best choice. It'll give you really great range, with a BC higher than even the 123-grain Lapua Scenar, higher lethality versus targets (a product of its larger mass and greater ease of fragmentation) and good barrier penetration (due to increased mass).
It's only 5mm longer than the 5.56 MOAL, and could be put into a 5.56 MOAL with some changes to the case. Maybe go to a 9.8mm base and a 41mm case, perhaps?
Anyway, I designed it with the M4/M16 in mind, and I even have my own, improved version of that rifle to go with it.

Jeff White
November 18, 2007, 10:25 PM
I think I've settled on an 87-grain 5.56 at 2800 f/s from a 15.25-inch barrel:

At what chamber pressure? How fast does the bolt carrier group move with this round? You get the timing off and you get bolt bounce which causes malfunctions.

How hot does it get? What about throat erosion in the barrel?

All some thing to think about......


The bullet is a high-frangibility bullet with a cross-shaped break in the cupro-nickel jacket on the tip,

Not likely to be Hague Convention compliant. So it' will only be the ultimate combat round for civilians.

Jeff

Deer Hunter
November 18, 2007, 10:27 PM
Bullet design has a lot more to do with fragmenting than velocity. If the military used much thinner jacked bullets, a new "ultimate" round would not be needed.

Nolo
November 18, 2007, 10:49 PM
At what chamber pressure? How fast does the bolt carrier group move with this round? You get the timing off and you get bolt bounce which causes malfunctions.

How hot does it get? What about throat erosion in the barrel?

All some thing to think about......

The answer to your question is I don't know. However, there are plenty of weapons that use high-velocity rounds, so that question is just one of the normal ones to be remedied in R&D.

Not likely to be Hague Convention compliant. So it' will only be the ultimate combat round for civilians.
I believe I already addressed this earlier in the thread.

Bullet design has a lot more to do with fragmenting than velocity. If the military used much thinner jacked bullets, a new "ultimate" round would not be needed.
High-frangibility is something that this project has been eying carefully. The velocity and high BC is for flat trajectory and increased range.

Dr. Peter Venkman
November 18, 2007, 10:50 PM
http://www.roadsquadron.com/Reference/ANH/DS/DS1_01.jpg
http://www.stardestroyer.net/Empire/Tech/Beam/DeathStar2.jpg

It's not the best choice for concealed carry on the person, but it's pretty easy to hide in a nearby galaxy.

Besides that, it totes the highest effective range out of any other weapon I've seen or handled.

Deer Hunter
November 18, 2007, 10:55 PM
Aw, the Hague Convention. The bane of unhindered war.

In all honesty, that kind of trajectory would be almost un-needed if this round would be used in infantry weapons on the main line. Fragmenting and high BC are nice, of course. I'm assuming you're looking for the one bullet to rule them all? One for the entire spectrum of small-arms? If so, I wish you luck. While a novel idea, there doesn't seem to be a need for it. Every tool has its place. The 5.56 and 7.62 NATOs serve well together. Even though I'd like to see a lighter bullet in a 7.62 NATO and the troops given rifles in said load, it wont happen.

Nolo
November 18, 2007, 11:03 PM
Aw, the Hague Convention. The bane of unhindered war.

In all honesty, that kind of trajectory would be almost un-needed if this round would be used in infantry weapons on the main line. Fragmenting and high BC are nice, of course. I'm assuming you're looking for the one bullet to rule them all? One for the entire spectrum of small-arms? If so, I wish you luck. While a novel idea, there doesn't seem to be a need for it. Every tool has its place. The 5.56 and 7.62 NATOs serve well together. Even though I'd like to see a lighter bullet in a 7.62 NATO and the troops given rifles in said load, it wont happen.
Which is why I'm ignoring it. I'll fight bureaucracy with bureaucracy. They want to make a stupid law, I'll name my weapon non-threateningly.

I think that this bullet would be able to be used effectively in all theaters of combat, from long-range duty to CQB. This round would produce as much energy as a 7.62x39 Soviet, fragment (I realize the Soviet is designed to tumble) much better to create far more devastating terminal effects, have far flatter trajectory to allow much longer shots without readjusting the weapon's sights, and would be much lighter, only a shade heavier than the 5.56.

GunTech
November 18, 2007, 11:51 PM
As an aised, one of the bullets that is usually mentioned in conjunction with the 6.5 Grendel is the Lapua Scena. This is generally considered as a match bullets, and some have wondered about its effectiveness.

This past weekend, I had occasion to go deer hunting, and used my 308 with 155gn Lapua Scenars, since that was the round the rifle was sighted with and I didn't have a chance to sight in with an appropriate 'hunting' bullet.

I was concerned that expansion and weight retention might be a problem, but figured that with proper placement, it would be fine for white tail.

Lapua Scenar proved to be extremely destructive - far beyond anything I could have imagined. I took two deer at about 150 yards, one right after the other, shooting offhand. The yearling had an exit wound large enough for me to put my fist in. While not shown in the photo, the doe had it's brains blown out

Ouch.

http://guntech.com/hunt/2fer.jpg

yesit'sloaded
November 18, 2007, 11:53 PM
Did it drop both of them or how far did they get? I'm guessing not very far.

Nolo
November 19, 2007, 02:03 AM
That looks like a drop.
What is that an equivalent to in 6.5mm?
123 grain?

Nolo
November 19, 2007, 02:12 AM
It looks like the 155 grainer is equivalent to a 97 grain bullet in 6.5mm, by my calculations.
But, then again, my calculations have been wrong before.

Tony Williams
November 19, 2007, 02:49 AM
The 6.5mm (.264") bullet weight with the same SDR as a .308" 155 grain would be 114 grains.

Nolo
November 19, 2007, 03:03 AM
How do you calculate that, Tony?

GunTech
November 19, 2007, 09:15 AM
Both deer dropped within a step or two of being shot. Here's a closer shot of the Lapua exit wound

http://guntech.com/hunt/bambi.jpg

jonboynumba1
November 19, 2007, 10:01 AM
When this subject comes up I also seem tho start thinking the sweet-spot for a general purpose round is really more around 6-6.5mm in diameter and .260 rem is right in the middle of that in the same .308 case already in use. There has been a lot of play with "middle" calibers in AR's lately. 6.8 (being a .270 fan I should like this one...but it's a bitt too big in my opinion...though it does EXACTLY what it's designer intended and is a neat mini-round. I think the 6.5 grendel is probably the best of these latest projects...I don't know if it will ever really catch on. But it seems to have lighter recoil than the 6.8 and just feels better in a carbine in general to me. I don't know if it would be worth chamging millitary calibers at this point...certainly n ot right now anyway.

In a longer range MBR it's hard to beat a 7mm projectile for a high BC with enough weight to have downrange "umph" .280 rem is basically just 7mm-erized .30-06 You could probably get a 150-160gr AP type round going close to 7 mag Again the 06/308 does it at lower chamber presures so perhaps that is the best compromise and we just need better projectiles. Going from 7.62 to 7mm would probably not be any more logical that the above at this point. But it would be a modest tweak in the right direction. IMHO

That being said our current and past rounds from .30-06 to .308 to 5.56 all are very close to the ideal for what they were in fact designed for. Especially the .30 cal rounds...the propellants and in some cases projectiles have been upgraded and tweaked over the years without causing any other needed changes. And if they could use Hornady TAP the little 5.56/.223 would be a lot more effective...that being said I still think they should have gone with a 6mm. projectile :)

The most interesting thing is the sub.50 large rounds like .338 Lapua people are "rediscovering" the long heavy skinny BT bullets are REALLY good at long ranges...been "redicovering" it since Elmer Keith's Day I guess. That and that heavy bullets in handguns knockstuff down better than little light bullets.

everallm
November 19, 2007, 10:06 AM
Quick question on the telescoping round format. The design's shown have either been in a straight walled cartridge or cartridge with the tip of the round protruding.

Just how reliable would these rounds feed from a magazine? The current technology is predicated on a cartridge and projectile form that is optimised for reliable feeding from a box magazine.

It would be a tad embarassing to have developed a Wunderkind round that jams like a bastard....8-)

Nolo
November 19, 2007, 10:18 AM
Everallm, I've been wrestling with that since I started looking at those rounds. None of the rounds I'm currently considering are designed that way, and I don't expect to repeat that trend. All are in standard format.

Tony Williams
November 19, 2007, 10:41 AM
How do you calculate that, Tony?
I have sectional density calculations set up on a little hand-held computer I have: I just need to know any two of the calibre, bullet weight and SD and it works out the third.

The formula I used for the program is included in the Basic Ballstics article on my website. It's this:

For metric measurements: multiply the projectile weight in grams by 1.422, then divide the result by the square of the calibre in millimetres. So for a 12.7mm bullet weighing 40 grams: (40x1.422)/(12.7x12.7) = an SD of 0.353

For Imperial measurements: divide the projectile weight in pounds by the square of the calibre in inches (if bullet weights are in grains, divide the result by 7,000).

Bullets of the same sectional density and the same shape will have the same ballistic coefficients and therefore the same velocity loss with range.

PercyShelley
November 19, 2007, 05:53 PM
One possible solution to the controlled pressure rise is to learn from rocket propellant technology (I have often wondered why this hasn't been done).

Produce a solid propellant which is cast into the case, with a hole down the length of it. When first ignited, the surface area of the inside of the hole would be small so not much gas would be generated. But as the propellant burns away, the hole gets bigger and the burning surface gets steadily larger, producing increasing quantities of gas. In theory, at least, that should result in a much more gradual pressure rise. It could also have the incidental benefit of keeping chamber temperatures lower, since the burning area wouldn't reach the case walls until right at the end of combustion.

Of course, it would require a different propellant chemistry and case filling technology, and you can forget about handloads, but I wouldn't have thought that would trouble the military too much.

I thought that too, and then I remembered something else about rocket propellant chemistry; liquid propellants have a higher specific impulse than any solid propellants. Specific impulse is related to the weight of the propellant biproducts and heat, which in turn would roughly correspond to working fluid speed of sound and therefore be beneficial to high velocity cartridges.

I recommend the use of an aqueous solution of hydroxylammonium nitrate, since that is, to the best of my knowledge, the best performing monopropellant so far developed. Hydrazine could be used as well, as its properties are well understood and there is a large amount of industry experience with it. Last I checked though, among those properties was a tendency to make your hair fall out, cause impotence, cancer and death. Emphasize the importance of cleaning your weapon to troops if this propellant is used.

For reasons of pressure containment, the chamber should be spherical. Burn rate will be moderated by catalyst geometry. The chamber will be sealed by a very strong, precisely machined valve in the rear, and during the initial pressure spike, but the bullet or a sabot it rides in.

SoonerSP101
November 19, 2007, 06:02 PM
.276 Pedersen. It passed the pig test!

Nolo
November 21, 2007, 06:00 PM
Percy, how do you intend to make the chamber spherical?

Nolo
November 26, 2007, 08:13 PM
Here's the latest incarnation of the Ultimate Combat Round:
http://i200.photobucket.com/albums/aa149/Nolo_photo/556mmFirebrandLambda556FAZephyr.jpg
It's the 5.56 Firebrand Lambda (Unofficially the 5.56 Firebrand Zephyr), it produces 1500 ft-lbs energy out of the muzzle, shoving an 87-grain bullet at 2800 f/s out of a 16-inch barrel. It's pretty much the exact same thing as 5.56mm Meteor, but with a 4mm shorter case and redesigned internal propellant with a smaller channel as well as a more deeply seated bullet.

Groovski
November 26, 2007, 11:38 PM
This page recommends an ideal "ultimate" cartridge as 6.5x45, plus lots of info on the history of cartridge development. As a bonus, pics of some very strange looking rounds tried over the years.

http://www.quarry.nildram.co.uk/Assault.htm

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