The Ultimate Combat Round

[Nolo]

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.

 

[Bobarino]

.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]

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


7.62x51 NATO
-Muzzle Velocity: 2800 ft/s
-Bullet Weight: 150 gr.
-Muzzle Energy: 2600 ft-lbs


7.62x39
-Muzzle Velocity: 2300 ft/s
-Bullet Weight: 125 gr.
-Muzzle Energy: 1500 ft-lbs


5.56x45 NATO
-Muzzle Velocity: 3000 ft/s
-Bullet Weight: 65 gr.
-Muzzle Energy: 1300 ft-lbs


5.45x39
-Muzzle Velocity: 2900 ft/s
-Bullet Weight: 65 gr.
-Muzzle Energy: 1200 ft-lbs


5.7x28 FN
-Muzzle Velocity: 2350 ft/s
-Bullet Weight: 30 gr.
-Muzzle Energy: 370 ft-lbs


6.5 Grendel
-Muzzle Velocity: 2700 ft/s
-Bullet Weight: 120 gr.
-Muzzle Energy: 1950 ft-lbs


6.8 Remington SPC
-Muzzle Velocity: 2625 ft/s
-Bullet Weight: 115 gr.
-Muzzle Energy: 1800 ft-lbs


.30-II
-Muzzle Velocity: 2400 ft/s
-Bullet Weight: 125 gr.
-Muzzle Energy: 1600 ft-lbs


7x45 Firebrand
-Muzzle Velocity: 2800 ft/s
-Bullet Weight: 135 gr.
-Muzzle Energy: 2300 ft-lbs


6.5x47 Firebrand
-Muzzle Velocity: 3000 ft/s
-Bullet Weight: 120 gr.
-Muzzle Energy: 2400 ft-lbs


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]

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]

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]

6.5 grendel seems like it would come closest

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]

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]

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]

.250 savage

 

[GunTech]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

I would have to say that the 7.62x54R round pretty much wins here.

 

[Nolo]

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]

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]

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!