.222 Remington with super-heavy bullet?

I've been looking closely into a variant of the .222 Remington with the case neck of the .223 Remington as a useful cartridge with ultra-heavy bullets.
How fast could such an animal send a 105-grain bullet out of a 20" barrel?
Just by eyeballing it, I think 2400 is a good estimate, but there could be factors in there that make it wayyy lower.
I hate to ask you guys such a trivial question, but I can't afford QuickLoad yet, or else I'd do it myself.
I already have to get CAD, QuickLoad, etc., etc...
So much money!
Anyway, help would be greatly appreciated.
Thanks in advance,
-Nolo

Uhhhh... current .223 rounds propel a 75gr at about 2700fps in a 20" barrel. The .223 has more case capacity than a .222 Remington. I don't have quickload, but I'm going to guess something more like 2000fps is a realistic guess for the combo you're suggesting.

More importantly, a spitzer style 105gr bullet in .22 cal, if anyone even makes one (?), would require a twist rate of something like 1-in-6" to stabilize. The tightest .22 cal barrels I've heard of are 1-in-6.5" and those are quite rare. Using such a tight twist really shortens barrel life and will likely cause pressure problems.

I have nothing against wildcats and experimenting, but I don't see this combo going anywhere good. Why not try one of the 6mm cartridges?

Who makes a 105gr .224 bullet? Just curious...

I have nothing against wildcats and experimenting, but I don't see this combo going anywhere good. Why not try one of the 6mm cartridges?
The actual bullet diameter I'm looking at is .236". But, obviously, there's kind of a shortage of bullets in that caliber. So I've gone with .224 for this question.
I think 6mm is a little big for what I'm trying to do.
I'm thinking about an entirely new platform and cartridge, so twist rate can be adjusted.
I just want to know whether it's possible without doing anything weird.
Essentially what I'm trying to do is get as close to Grendel ballistics as I can in as small a package as I can.

...why?

Despite the legions of fans (Of whom it seems very few actually own a rifle chambered for it), the Grendel is not the be-all end-all of rifle cartridges that it is hyped up to be...

I got to play with one a while back and I really couldn't see a thing it could do practically and ethically that a .223 couldn't do at half the price... or that a better chambering couldn't do better.

Long story short, everything is a compromise... you want more power, you get more recoil, you're going to need a bigger case, etc, etc.

I think 105 .224s do exist, but I've never used them. Perhaps JLK or Berger has some type like that or near that weight?

That said, neither .222 or .223 is going to be too great with those... I can guarantee you that you are going to have to seat bullets like that far too long to fit into any normal sized magazine for those cartridges. .222 Rem Mag may be a slightly better choice, but I can't see why you would do this when you could move to 6mm or .25 cal for bullets of that weight.

6X45 is fairly close to what you are envisioning.

Take a look at the new(ish) 6XC cartridge. It looks wonderful. 6 Benchrest is also good. These would be much better cartridges to propel 105gr at a nice flat-shooting speed.

BTW, .236" is closer to .243" (6mm) than to .223.

the Grendel is not the be-all end-all of rifle cartridges that it is hyped up to be...
I don't claim it to be. However, what I am concerned with is its BC (with 123-grain bullet), which allows the bullet to maintain fragmentation velocity (2000 fps with a properly-designed bullet, according to tests with Mk. 262) out to 300 yards (90 percent combat range) with low (2550 fps) velocity.
In addition, this performance has many benefits outside of the infantry rifle, and into the SAW, LMG and DMR weapon systems.
I'm also thinking about a lighter (90-grain) bullet at higher velocity.
I'm trying to get said performance (105 @ 2550 out of 20" @ 50KPSI) in as light a package as possible (otherwise it gives no advantages over other designs out there), and I was wondering if I could approach that with .222 Remington.
Maybe if I used .223 Remington as the base... Of course that means my OAL has to go up.
BTW, .236" is closer to .243" (6mm) than to .223.
Yeah, but it makes me less optimistic, as there will be a performance decrease when you neck down. :(

If your goal is terminal performance, I think you'd have more success pursuing variations in bullet construction than trying to work out in the far end of what's ballistically plausible with really long bullets.

Alternatively, you could begin examining saboted projectiles.

If your goal is terminal performance, I think you'd have more success pursuing variations in bullet construction than trying to work out in the far end of what's ballistically plausible with really long bullets.

Alternatively, you could begin examining saboted projectiles.
I'm already brainstorming all of that. If only I had a way to get some empirical data on this stuff.
I'm convinced that you can make a bullet that both penetrates non-armor barriers (like car doors) and has excellent fragmentation properties on flesh.
The reason is because a hard surface with little behind it (car door) is different than a soft compound surface (like a human). I want to exploit that difference.
The only question is how much research will it take to make it suitable for mass-production.

I just did a little playing with QuickLOAD for you. I set it up with a .222 Rem cartridge, moly-coated 75gr Hornady BTHP manually bumped up to 105gr, 2.490 OAL, 50Kpsi limit, and 20" barrel. Crude, but hopefully ballpark.

Cartridge : .222 Rem.
Bullet : .224, 75, HDY BTHP M 2279, friction proofed
Cartridge O.A.L. L6 : 2.490 inch or 63.25 mm
Barrel Length : 20.0 inch or 508.0 mm

Predicted Data for Indicated Charges of the Following Powders.
Matching Maximum Pressure: 50000 psi or 344 MPa

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 ordering 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 85%. These powders have been skipped.

Powder type Filling/Loading Ratio Charge Vel. Prop.Burnt P max P muzz Btime
% Grains fps % psi psi ms
--------------------------------- -------------------------------------------------------
Norma MRP 113.0 28.0 2448 95.0 50000 12704 1.172 ! HOT LOAD !
Alliant Reloder-25 117.6 28.4 2431 97.0 50000 12445 1.172 ! HOT LOAD !
Somchem S365 106.0 25.6 2427 100.0 50000 11068 1.179 ! HOT LOAD !
Acc.Arms XMR4350 107.8 25.6 2420 99.9 50000 11012 1.177 ! HOT LOAD !
Hodgdon H4350 105.0 25.8 2418 96.8 50000 11692 1.176 ! HOT LOAD !
Alliant Reloder-22 111.5 27.4 2414 93.3 50000 12099 1.177 ! HOT LOAD !
Winchester WXR 110.3 27.5 2413 93.1 50000 12100 1.177 ! HOT LOAD !
Norma 204 107.1 26.3 2411 95.8 50000 11741 1.183 ! HOT LOAD !
Hodgdon H414 96.5 25.5 2404 95.9 50000 11556 1.187 ! HOT LOAD !
Vihtavuori N165 112.8 28.3 2403 96.8 50000 11600 1.179 ! HOT LOAD !
Rottweil R905 111.6 27.1 2396 91.9 50000 11828 1.177 ! HOT LOAD !
Rottweil R904 106.4 25.8 2392 96.1 50000 11418 1.193 ! HOT LOAD !
Vihtavuori N560 107.1 27.2 2389 91.1 50000 11776 1.181 ! HOT LOAD !
IMR 4831 109.3 26.5 2388 96.1 50000 11322 1.190 ! HOT LOAD !
Winchester 760 94.4 24.9 2385 95.6 50000 11200 1.187 ! HOT LOAD !
Rottweil R907 94.6 24.0 2383 98.5 50000 10861 1.188 ! HOT LOAD !
Vihtavuori N550 97.2 24.6 2383 98.1 50000 11093 1.196 ! HOT LOAD !
Hodgdon H870 126.6 32.1 2381 85.5 50000 12897 1.180 ! HOT LOAD !
IMR 7828 113.5 27.3 2378 89.8 50000 11777 1.176 ! HOT LOAD !
Ramshot Magnum (Big Boy) 113.3 29.4 2377 90.2 50000 12149 1.176 ! HOT LOAD !
IMR 4350 103.6 24.9 2376 94.9 50000 11099 1.182 ! HOT LOAD !
PB Clermont PCL 517 113.4 29.4 2376 90.2 50000 12138 1.176 ! HOT LOAD !
Alliant Reloder-19 108.2 26.0 2374 93.2 50000 11318 1.182 ! HOT LOAD !
Vihtavuori N160 107.8 26.7 2365 94.8 50000 11060 1.183 ! HOT LOAD !
Hodgdon H4350 SC 105.0 25.8 2362 92.8 50000 11221 1.178 ! HOT LOAD !
Somchem S385 107.4 26.5 2360 94.7 50000 11059 1.197 ! HOT LOAD !
Hodgdon H380 95.2 23.9 2357 97.8 50000 10735 1.215 ! HOT LOAD !
Norma 203 old 97.8 23.3 2352 99.7 50000 10279 1.215 ! HOT LOAD !
Rottweil R903 97.9 23.3 2351 99.6 50000 10287 1.215 ! HOT LOAD !
Vihtavuori N160 ,fast lot 99.2 24.6 2349 98.1 50000 10388 1.193 ! HOT LOAD !
SNPE Vectan Sp 7 92.3 24.0 2349 98.9 50000 10361 1.202 ! HOT LOAD !
Hodgdon H4831 SC 109.0 27.4 2344 89.6 50000 11285 1.181 ! HOT LOAD !
Hodgdon H1000 114.4 28.6 2331 89.3 50000 11407 1.182 ! HOT LOAD !
Rottweil R901 85.9 20.3 2287 100.0 50000 9039 1.233 ! HOT LOAD !
PB Clermont PCL 513/520 132.8 33.0 2285 79.5 50000 11391 1.193 ! HOT LOAD !
Vihtavuori N170 117.4 29.8 2285 80.9 50000 10709 1.194 ! HOT LOAD !
Vihtavuori 24N41 120.1 31.1 2284 78.0 50000 11355 1.193 ! HOT LOAD !
Vihtavuori 20N29 130.8 34.2 2262 76.7 50000 11435 1.198 ! HOT LOAD !
Hodgdon H50BMG 124.0 32.1 2155 63.3 50000 9991 1.218 ! HOT LOAD !
TLP A 502(RH) ,test only 137.1 32.6 2139 61.5 50000 9500 1.222 ! HOT LOAD !
NC A3502 ,test only 134.5 32.0 2086 54.8 50000 8435 1.233 ! HOT LOAD !
V1734 7-multiperf ,test only 150.6 35.8 1754 32.2 50000 5322 1.335 ! HOT LOAD !

Hm, hardly 2400 fps with a very compressed load and a 75 gr bullet.

QuickLOAD sure is a cool program.

Wayyy better than I was expecting. 2400 was optimistic.
2450! Whoohoo!
Looks like this is an avenue I can actually take.
If I use .236 caliber, that might get me up to 2500. I think I can garner the extra 50 fps pretty easily with some powder research afterwards.
I probably won't get finished until I'm in my 30s, but now there's some hope it will actually get finished.
Thanks for the glimmer of hope!
It says the loads are "hot", at 50KPSI, what does that mean, exactly? I thought that .222 Rem was proofed for 50KPSI.
CBS, he said he manually bumped it up to 105. Not sure how you do that in QL, though. Of course, I've never used the program.
I'm questioning the accuracy of the data, but it's still very encouraging to me.

Hm, hardly 2400 fps with a very compressed load and a 75 gr bullet.

QuickLOAD sure is a cool program.

Like I said, I started with data for a 75gr bullet and manually changed it 105gr. I just didn't see a 105gr bullet listed in QuickLOAD (I could have missed it though).

The highest I've seen for .224 is 90 grain. But like I say, the end idea is to be in .236 caliber.

I read an article in either Guns and Ammo or American Rifleman (possibly something else) that had a .22 ackley cartridge hitting targets at 1000 yards. I think it may have been something like the .22 AI Magnum (.308 necked down) but I'm not sure. May give you some ideas. I'll see if I can't track the magazine down and post which issue it was.

JesseL's Quickload is about as close as you are going to get without some detailed calculations followed by actual prototyping and range testing.

The real world Myra .243 (.243x.222 Rem) of about 35 years ago would only do 2300 fps with a 100 grain bullet. Maybe powder selection is better now. Maybe fiddling with the case neck length would gain enough volume to make 2400. You could run at higher pressures, the .222 is NOT a 50kpsi cartridge like the .223. But the higher sectional density of a .236" bullet vs a standard .243" will work against you.

All else I have seen in the general range you are talking about is either a larger volume case or was tested as a varmint rifle with lighter bullets... or both.
Things like .230 Ackley Short, .23 1/2, 6x43, or .25 Copperhead.
There was a gunzine writer who furnished his wife with a 6x.222, loaded it with 87 grain bullets and said it was the equal of a .250 Savage; not at muzzle velocity but a couple hundred yards down range where the superior BC of a .243" over a .257" let it "catch up."

Suggest you save up from your allowance and get Quickload, you need some real tools instead of internet threads.

And do your first round of wildcatting with .243" barrel and bullets, that will be a lot cheaper than special order .236"s.

Random thoughts:
It is no particular trouble to get a 90 grain .224" up to 2700 fps out of a .223. There were some 100 grain bullets made to load to AR magazine length but I have no data for them.

It is no particular trouble to get a 90 grain .224" up to 2700 fps out of a .223.

What barrel length? Those .22's have such small bores, relative to fairly decent case capacity, that barrel length is huge. From reading way too many reviews of various rifles, AR's with 24" barrels pretty much get the claimed velocities, while AR's and piston-driven semiautos with 16" barrels seem to lose far, far more than the standard 25fps/inch rule of thumb - they seem to lose more like 50fps/inch.

Mine is 28", 6.5 twist.

"I just want to know whether it's possible without doing anything weird." I don't think you can get away from the "weird" part with this project.

I would look at the stats of a 6x47 lapua, or a straight up 6x45.

http://www.btammolabs.com/tests/4.htm

These people got a 100 grainer to 2450 out of a 20" AR15. Don't recall where the accompanying forum thread was for further details.

Seems to me like a bunch of work to make the .22 bore into something it isn't. If this is just paper gymnastics without existing equipment that needs to be incorporated then there are better places to start. Like the SPC.

I used a compressed load of 26.5 gns of BL-C on a surplus 62 gn BTHP bullet out to 700 yards with an average accuracy of 8" off of a sandbag rest w/ my antique benchrest rifle. This is with a 1 in 9" twist, so I can't let you in on the heavy VLD performance stats. Go to the 6mmbr.com or Benchrest.com forums for better info on the long range .22 performance.

Anything further, and you will probably just run out of steam and frustrate yourself. Even the .22-250's lose their oomph past 700 yards.

These people got a 100 grainer to 2450 out of a 20" AR15. Don't recall where the accompanying forum thread was for further details.

Seems to me like a bunch of work to make the .22 bore into something it isn't. If this is just paper gymnastics without existing equipment that needs to be incorporated then there are better places to start. Like the SPC.
Really?
The SPC weighs about as much as a 7.62x39. It has minimal benefits for a SAW gunner. It is probably about as effective as Mk. 262 Mod. 0. Its trajectory falls off after 300 yards.
This cartridge weighs less, is probably more effective against human targets, is way better for a SAW and has a flat trajectory for a round its size.
The SPC is a great cartridge, but it's exactly what it says: a special-purpose cartridge. What I'm working on is a general-purpose cartridge.

I didn't say the SPC is the end all be all, I said it's a place to start.

Your 100 grain .222 weighs 20% more than M855. Trimming 0.06" off the case with the .222 isn't going to save anything except powder space, which is too short to begin with. That's more than half your weight advantage v 6.8 gone right there.

With such a small piston area performance will be terrible in short barrels.

Even with a full sized barrel the 6.8 SPC is putting out 30% more power at the muzzle, better BC or not the heavy .22 isn't catching up in power until 400 yards. By which point it's dropping like a rock good BC or not. The 6.8 SPC, also dropping like a rock, is still flatter out to 600+ yards.

What general purpose is this good for?

I didn't say the SPC is the end all be all, I said it's a place to start.

Your 100 grain .222 weighs 20% more than M855. Trimming 0.06" off the case with the .222 isn't going to save anything except powder space, which is too short to begin with. That's more than half your weight advantage gone right there.

With such a small piston area performance will be terrible in short barrels.

Even with a full sized barrel the 6.8 SPC is putting out 30% more power at the muzzle, better BC or not the heavy .22 isn't catching up in power until 400 yards. By which point it's dropping like a rock good BC or not. The 6.8 SPC, also dropping like a rock, is still flatter out to 600+ yards.

What general purpose is this good for?
Apologies, I didn't make myself clear. You're correct that this particular cartridge is not anything desirable, but it creates a starting point for something that is, the .236 that is the ultimate goal. That cartridge is ballistically almost identical to the 6.5 Grendel, which does exceed the 6.8. However, the .236 cartridge would be 20% or more lighter, which is extremely desirable. In addition, the principles that it works off of (similar to the Mk. 262, which can fragment at as low as 2050 fps) make it an extremely effective cartridge inside 300 yards, which is where the majority of combat engagements occur. Since it is ballistically equivalent to the Grendel, it exceeds the ballistic performance of the .223 Rem/5.56 NATO, and (I believe, but Grendel data is sometimes suspect) the .308 Win/7.62 NATO, which means that it fulfills a general-purpose role quite well. In addition, terminal ballistics is not nearly as important for a SAW or DMR because they rely on volume of fire and shot placement (respectively) anyway.
Like I said, this cartridge isn't too impressive as it stands, but after some refinement, which I hope to do while in school, it should come out at something serious to look at. The data as it stands has given me hope that the performance goal (.236" 105 grain @ 2550 fps @ 50KPSI) is actually attainable with some research and devotion.
Once I do get all the bugs (there are a few that are already apparent, and I expect about 10X more down the road) worked out, I really do think this is the answer to the multipurpose cartridge.

What about the .220 Russian? Seems that it's usually loaded with stubby little bullets, but there's plenty of room in an AK magazine for longer bullets, and since the taper hasn't been screwed with, it should feed from the same. A custom barrel to accommodate the longer bullets, and it should be quite capable of tossing the 90 grain VLDs @ 2800 or thereabouts.

I don't think that extra performance is really warranted. It might be able to send a 105-grain bullet at 2700 fps, but why? The only weapon that would need performance like that would be a serious sniper rifle, and I already have a scheme to do so with this cartridge.
Here, this is the best description of the .236 cartridge concept that I have yet written. It's made for people with less knowledge of firearms than most people on THR (and it's still freakin' long), but it should be enlightening as to what exactly I'm shooting for:
If you had to ask me right now what thought the US armed forces should be using on the battlefield today, I would answer you with this:
This is a family of 5.85mm (.236") cartridges that, I believe, provide the answer to a long-attacked problem: logistics.
In the 1950s, the United States Army attempted to solve the problem of logistics in the military, as the post-WWII Army had, in service, 3 cartridges and four rifles, which greatly complicated getting ammunition to those who need it most.
What the US Army came up with was the 7.62 NATO, but as a universal round, it was a failure. It was heavy to carry for machine gunners, and was too powerful for lighter rifles and carbines to fire on full-auto.
In reaction, the Army later adopted to ultra-light 5.56x45mm NATO, also known as .223 Remington, which they continue to use today.
In the wake of the invasions of Afghanistan and Iraq, small lots of 5.56 were being delivered to special purpose rifleman in the field that could potentially change the way people think about small arms in particular.
This round was the Mk. 262 Mod. 0.
It featured the heaviest bullet the 5.56 could accommodate, a 77-grain open-tip match bullet with a super-thin jacket, and fired it at speeds matching that of the 7.62 NATO (which is slower than the previous 5.56x45 rounds). It was formerly believed that fragmentation could not occur for a military round at under about 2500 fps, which, for a round that relies heavily on fragmentation, as opposed to sheer bullet diameter, means that the round has to either have an enormous ballistic coefficient to hang on to every last foot-per-second of speed, or be going extremely fast to make sure that it has speed to burn. The Mk. 262 Mod. 0 changed that thinking.
The Mk. 262 showed that a bullet could be designed to fragment at velocities as low as 2000 feet per second, which meant that, with a properly designed bullet, the cartridge could be lightened, since the race-car like ballistics were not really needed anymore. Now, the 77-grain OTM bullet that the Mk. 262 fired did indeed have a superior ballistic coefficient, the best that an operational 5.56 can have. However, the ballistic coefficient, from a design perspective, is low, constrained by the overall length of the magwell of the AR-15 and the magnum-style case of the 5.56.
Using the lessons learned from the Mk. 262 Mod. 0 and discarding the 5.56 round entirely, I have come up with a cartridge system that effectively solved the logistics problem, increases terminal and other performance in nearly all areas, and reduces weight from other 5.56 replacement proposals by anywhere from 20-30%.
The cartridge comes in four "flavors":
M950 Ball: This is heavily based off of the Mk. 262 discoveries. Designed to perform against human targets, but also with barrier and vehicle penetration in mind, the M950 shoots a 105-grain, .236-caliber bullet at 2550 feet per second, using a modest pressure of 50KPSI, thanks to slow-burning powders. Ballistics are very similar to the larger 6.5 Grendel cartridge.
M955 Light Armor-Penetrating: This round is designed with barriers in mind. It fires a 97-grain, steel-cored projectile at 2600 feet per second. It mimics the capabilities of the M855 Green Tip round (while unconstrained by European preferences for "non-nasty" ammuntion), and it well-suited to SAW use due to its light weight and long range.
M956 LAP-Tracer: Similar to the M955, the M956 is a tracer round in addition to having some limited penetrating capability. Based on technology developed during the 6mm SAW ammunition program, its tracer can be seen out to 900 yards, further than both the 5.56 and 7.62 tracers.
M957 Dedicated DMR-Sniper; AP: The oddball of the M950 series, the M957 has a slightly elongated case (by 1mm) in order to prevent it from feeding into standard assault rifles and machine guns. In addition, it will not fit into the standard STANAG magazines of assault rifles, preventing cases of mistaken identity that could lead to possible deadly jams on the battlefield. For further safety, the round has a bright red band around the case neck, as well as a crimping in the neck, should the band wear off.
Why? The M957, due to its dedicated sniper role, operates at 10KPSI higher (60KPSI) than its standard companions. This allows it to send its 105-grain bullet--essentially a match version of the bullet used in the standard ball loading, with the addition of a tungsten penetrator--at up to 2750 f/s, giving it a range unequaled by rounds in the same class.
Sniper rifles that will feed M957 will also feed the other typed of ammunition as well, as it poses no long-term threat to the rifle's health. In addition, standard rifles and MGs will be proofed to withstand the pressures of this round, in the event that such a round does actually manage to be fed into one of them.
However, such pressures do no good for the standard action, and would wear them out quickly (especially MGs) if fed a steady diet of high-pressure ammunition.

In my opinion and research, a set of cartridges comparable to these would provide a true optimum for the modern warfighter, and would serve well in many respects for many years. Other cartridges that have been suggested for a full-out rifle replacement include essentially "Grendel-Magnums" that exceed the performance of that cartridge by usually less than 200 fps (and exceeding the OAL of the M16 by several millimeters). However, the Achilles heel of those rounds is that they weigh far more than the 5.56 NATO and even the 7.62x39mm, which is no lightweight. The M950 series of cartridges stay much closer to the 5.56 in terms of weight, being only slightly heavier. This cartridge accomplishes all the tasks that a modern military requires, all in the same four types of cartridge that have been with us for many, many years.
The decision to make the Sniper/DMR round a slightly different one originated with the realization that, due to special requirements by snipers, a single TYPE of cartridge could not possibly replace the standard set of four (ball, AP, tracer, match). The four types could possibly be reduced to three, but no less than that, as snipers have to have match ammunition and it is just not feasible from a production standpoint to issue every soldier match ammunition. In addition, the requirements for the sniper cartridge are the most onerous, requiring more range than is needed by any stretch of the imagination for an infantry rifle, and even a squad-level MG or SAW. Thus, since the sniper ammunition must be distinct anyway, I decided that a small augmentation of performance was in order, and that, as long as the high-pressure cartridges could not be used in the basic grunt's rifle, the Sniper/DMR load could be made to utilize higher pressures. Now, the STANAG magazines and infantry ammunition can all be used in the envisioned sniper rifle; the design would be such that they would be compatible. However, the dedicated sniper magazine, which is the only one capable of holding the M957 ammunition, could not be used in the standard rifle.
It is my hope that the ammunition types could be reduced to three: ball, AP/tracer and match, but I am just not certain that a 105-grain bullet could fit all of the components necessary to make it effective as both an AP an tracer round inside of it. Therefore, I created the M855 act-alike, the M955.
By the way, I'm not entirely certain about whether the statement about fragmentation and 2500 fps is entirely correct, but I know that it surprised me and from all the cartridges that I've looked at, appears to hold true. Please correct me if I'm wrong on this inference.
Here's a crude render of the four types, notice the sniper round is slightly longer (by 1mm at the neck):
http://i200.photobucket.com/albums/aa149/Nolo_photo/M950Family.jpg

Apologies, I didn't make myself clear. You're correct that this particular cartridge is not anything desirable, but it creates a starting point for something that is, the .236 that is the ultimate goal. That cartridge is ballistically almost identical to the 6.5 Grendel, which does exceed the 6.8.

Understood, forget about .22s, what you're chasing is essentially an 85% Grendel.

Instead of getting there with a very heavy for caliber 6mm, how about using a lighter 6.5mm bullet?

The Grendel is 120 grains (SD=0.25, G1 BC=~0.55) at 2550 (20"). That great BC is achieved with a long Lapua VLD bullet which probably causes more OAL problems than it's worth. But we'll keep it for the sake of argument and give similar bullets to the others. Swapping them for something less aggressive across the board won't change the relative rankings.

Scale down to 6mm, that'd be 100 grains, we'll give it the same BC and velocity.

And scale it down to a 100 grain 6.5mm bullet and dock the BC to 0.45.

V0 E0 V300 E300 V600 E600 600y drift 600y drop
6.5 120 2550 1730 2090 1170 1680 750 29" 128"
6.0 100 2550 1440 2090 970 1680 630 29" 128"
6.5 100 2550 1440 2000 890 1520 510 37" 137"


Past 300 yards the heavy 6mm is beginning to pull away, not spectacularly so until you're pretty far out there but if it's free you may as well take it.

But consider that with the greater piston area of the 6.5mm bore the same case capacity will get you another 75-100 fps at the same pressure. The stubbier bullet makes things easier regarding OAL constraints, or lets you get away with a more aggressive ogive, assuming feed or fragility aren't the limiting constraints.

Run it again with another 75 fps on the light 6.5mm :


V0 E0 V300 E300 V600 E600 600y drift 600y drop
6.5 100 2625 1530 2060 950 1570 550 35" 129"


Equally flat to 600 yards. A little more energy on target inside 200 yards. Better performance in carbine length barrels. Ammunition no heavier.

Worse in the wind, slightly more recoil, a little less energy way out there.

Aspade, what you are suggesting would be fine for a caliber that only has to satisfy the infantryman. But what about the SAW/LMG gunner? What about the sniper? (Essentially, it seems you're going for a scaled down 6.8 SPC of sorts. Maybe not exactly, but it looks close)
If you just cater to the infantryman, you gain practically nothing. These other areas must be covered. We hashed over this time and time again over what was better, faster or more energy retentive in The Ultimate Combat Round thread. What we (actually, just GunTech) came up with at the end was the 7.62x45mm Czech necked to 6.5 shoving a 144 grain bullet at 2550 fps. Now, this cartridge does not have nearly the BC of that round, but I also considered it to be excessive.
So I worked out some weight savings, and this is what the result of that research has come to.
EDIT: Also, I'm not trying for a super heavy bullet in 6mm. I'm trying for a super heavy bullet with a BC equal to the 6.5 123-grain Lapua Scenar bullet in 5.85mm. According to my calculations, the equivalent BC in that caliber is 104 grains, I just rounded it off to 105.

I don't see the government buying an incremental improvement in rifle ammunition. They are waiting for The Next Big Thing. See the article in the new American Rifleman about the current state development of telescoped ammo? Plastic cases or no cases at all will save a lot of weight.

Tests are being done with M855 bullets for easy comparison with 5.56, but that does not mean they couldn't end up with something ballistically better in the end.

I don't want to discourage you on this project, but Jim Watson is right on the money.

Changing bullet diameter by .008" to get to .236" is going to be a real tough road. We already have pretty small gaps in established bullet diameters and there is little to be gained by splitting the difference.

Also keep in mind the bigger picture. A tiny weight savings is not worth a whole other round. Your M950 and M955 proposed rounds probably aren't different enough to justify the 2 of them. The performance difference in most applications is most likely negligible and now you're back to the logistics nightmare. The weight savings of 8 grains per round between the two adds up to a whopping 1/3 of a pound.

Once again, I don't mean to discourage, but work on the "big leap" that Jim talked about. Don't make the little improvements with existing technology. Make your own technology with performance that is unheard of and people will listen.

I don't see that the light 6.5mm bullet gives up much to the 6mm in the SAW role.

The trajectory is even to 600 and within a foot of each other past 800 yards - at which point they've both dropped more than 20 feet. The 6mm has more energy at long range but the difference isn't even 10% until 500 yards. At 800 yards it's 20%.

Chasing 800 yard performance in somethat that is first and foremost a 0-300 yard tool isn't general purpose. Building your DMR around a carbine round - or vice versa - isn't general purpose either.

Getting reasonable 600 yard performance is worth chasing, the SPC falls short there due to its stubby bullet but that can be bumped up to acceptable without going all the way down to a 6mm needle.

I don't see the government buying an incremental improvement in rifle ammunition. They are waiting for The Next Big Thing. See the article in the new American Rifleman about the current state development of telescoped ammo? Plastic cases or no cases at all will save a lot of weight.

Tests are being done with M855 bullets for easy comparison with 5.56, but that does not mean they couldn't end up with something ballistically better in the end.
I don't want to discourage you on this project, but Jim Watson is right on the money.
work on the "big leap" that Jim talked about.
I am already brainstorming plastic-cased ammunition and sabot rounds that are ballistically identical to this ammunition. This is really just a performance springboard, but I'd like to take it full-term, that way there are less bugs to work out when I do end up converting it to a more cutting edge format.
Also keep in mind the bigger picture. A tiny weight savings is not worth a whole other round. Your M950 and M955 proposed rounds probably aren't different enough to justify the 2 of them. The performance difference in most applications is most likely negligible and now you're back to the logistics nightmare. The weight savings of 8 grains per round between the two adds up to a whopping 1/3 of a pound.
I don't blame you for not reading that whole huge monster, but I addressed that previously:
It is my hope that the ammunition types could be reduced to three: ball, AP/tracer and match, but I am just not certain that a 105-grain bullet could fit all of the components necessary to make it effective as both an AP an tracer round inside of it. Therefore, I created the M855 act-alike, the M955.

I will just add this one little tidbit. We have many popular chamberings in:

.22 cal
.24 cal
.25 cal
.26 cal
.27 cal
.28 cal, and
.30 cal

*Arguably*, what's missing is a .23 cal and/or a .29 cal, which could fill some conceivable niche, and strike just the right balance of tradeoffs.

So I welcome your budding engineering enthusiasm, Nolo. You may or may not be onto something, but I think this idea is worth pursuing:

I'm convinced that you can make a bullet that both penetrates non-armor barriers (like car doors) and has excellent fragmentation properties on flesh.
The reason is because a hard surface with little behind it (car door) is different than a soft compound surface (like a human). I want to exploit that difference.

You may or may not be onto something, but I think this idea is worth pursuing:
And that is the heart of this system.

*Arguably*, what's missing is a .23 cal and/or a .29 cal, which could fill some conceivable niche, and strike just the right balance of tradeoffs.

They aren't missing, at least not completely.

P.O. Ackley designed and sold at least two different .230s for use in states where regulations were written "no caliber under .23" so as to keep people from hunting big game with Swifts, etc. So he just necked up a couple of big .224s to .230 and had made bullets to suit. Bullets ran 60-75 grains with heavy jackets for deer medicine.

Handloader Magazine once did a piece on the B-29 Ultimate Wildcat. Pure fiction and photoshop but they made it sound as good as anything here.

There is no supply of those bullets, so they are pretty much missing.
I gave much thought to a a 6.17mm (.243") round, but it came out bigger than I wanted. I wanted an approximate weight of .029 lbs per round for the standard-cased ammo, but I wanted a bullet of greater caliber than the .224. If you look at it, .236 is right in the middle (the mean of .243 and .224 is .2335). In fact, you could say I'm already using a 6mm bullet, because the true diameter of the .236 is 6mm (the true diameter of .243s is 6.17, but you guys knew that). Nominally, however, the round is 5.85mm. I really want the round to be comparable to 5.56 in weight, even if it will be heavier.

There isn't much supply of .236" bullets either, but there was at one time a wildcat known as the "23 1/2" and the originator had to get them somewhere. Schroeder still listed them as recently as 1997; I have nothing later.

If you are serious about taking this past the Internet Discussion level of development, you will probably just have to suck it up and have swage dies made to suit.

Pac-Nor will make you a barrel at their regular price, if .234" is close enough.

.234" is fine.
I will have to do a lot to take this past fancy PS images and concept, but thankfully I'm going to college for mechanical engineering in a gun-friendly state. I think I should be able to do research on it for real. Maybe I'll even write my Master's dissertation on it.

Been thinking about this again, and I think that a 107-108 grain .243" bullet would actually be better.
Could probably run a bit faster, and the BC of the 107s is summat like the Grendel, so...

So you're basically look looking at 6mm-.223/6x45mm with heavy bullets now?

From what I can see it's been done but it's very easy to get into excessively high pressures.

the aforementioned 6mmXC is great. I've been shooting one a while now and love it. 6x47 (necked down 6.5x47 lapua) is nearly identical in every way except you get lapua brass instead of norma/tubb brass, and small vs large primers.

So you're basically look looking at 6mm-.223/6x45mm with heavy bullets now?

From what I can see it's been done but it's very easy to get into excessively high pressures.
Yeah, but with a shorter case (40.5mm).
And I am only looking to do 2650 fps.

the aforementioned 6mmXC is great. I've been shooting one a while now and love it. 6x47 (necked down 6.5x47 lapua) is nearly identical in every way except you get lapua brass instead of norma/tubb brass, and small vs large primers.
6mmXC is fine for benchrest, this is supposed to be a military caliber.
And as light as possible.

Yeah, but with a shorter case (40.5mm).
And I am only looking to do 2650 fps.

I don't think you can do it.

Hodgdon has load data for 6x45mm. The heaviest bullets they list are 100gr and they're just barely getting over 2600 fps with max loads. Adding a few grains of bullet weight and subtract some case capacity doesn't improve the situation.

Some of the new non-canister double-base ball powders they've been playing with might make it possible, but that's pure speculation at this point.

I don't think you can do it.

Hodgdon has load data for 6x45mm. The heaviest bullets they list are 100gr and they're just barely getting over 2600 fps with max loads. Adding a few grains of bullet weight and subtract some case capacity doesn't improve the situation.

Some of the new non-canister double-base ball powders they've been playing with might make it possible, but that's pure speculation at this point.
K.
I'll continue to look at it, though.
It's nice because it would fit into an M16 OAL...

6mmXC is fine for benchrest, this is supposed to be a military caliber.
And as light as possible.

i think you've misunderstood what this cartridge was invented for.

good luck

i think you've misunderstood what this cartridge was invented for.
Elaborate, Taliv.
From everything I've read, 6XC is a target caliber.

Right now you're going to run into limits of pressure or case capacity no matter how you slice it. The only thing that can really change that is advancements in propellant technology.

So within the envelope defined by the AR/M-16 platform in terms of pressure and OAL, the only direction you can go to improve ballistic performance (in terms of bullet weight/ballistic coefficient/velocity) over the 5.56x45mm is to go to a fatter cartridge family. Obviously this is what's been done with the 6.5 Grendel and the 6.8 SPC. The stuff GunTech has done based on the 7.62x45mm Czech round has intrigued me (http://www.thehighroad.org/showthread.php?t=371963).

Of course this tends to run contrary to your goal of minimal weight. TANSTAAFL.

Right now you're going to run into limits of pressure or case capacity no matter how you slice it. The only thing that can really change that is advancements in propellant technology.

So within the envelope defined by the AR/M-16 platform in terms of pressure and OAL, the only direction you can go to improve ballistic performance (in terms of bullet weight/ballistic coefficient/velocity) over the 5.56x45mm is to go to a fatter cartridge family. Obviously this is what's been done with the 6.5 Grendel and the 6.8 SPC. The stuff GunTech has done based on the 7.62x45mm Czech round has intrigued me.

Of course this tends to run contrary to your goal of minimal weight. TANSTAAFL.
No, but there is such a thing as a cheaper lunch.
GunTech started that stuff because of a thread I started. I am familiar with the work.
Propellant technology, contrary to popular belief, I believe is not yet at its apex.

I definitely applaud both you and GunTech for straining to push the limits of small arms technology.

I suppose you could explore the other direction - going to smaller diameter cartridge bodies would allow you to run higher pressures without increasing bolt thrust. Propellant should burn more efficiently at higher pressures and potentially compensate for the lost volume. In addition you could gain magazine capacity and short-barrel performance.

The gotchas then become brass and primer flow, and perhaps a little more sensitivity in gas-operated mechanisms.

The 6xc is mostly used for competition but competition that includes rapid fire stages, unlike similar cartridges like the 6BR. Note the similarity in the tubb2k and the ar15.

I wasn't trying to say it's the answer to whatever problem you've got. I'm just saying it would be a good case to start from. Or go back and look at the cartridge it was made from which iirc is the 220russian.

I definitely applaud both you and GunTech for straining to push the limits of small arms technology.

I suppose you could explore the other direction - going to smaller diameter cartridge bodies would allow you to run higher pressures without increasing bolt thrust. Propellant should burn more efficiently at higher pressures and potentially compensate for the lost volume. In addition you could gain magazine capacity and short-barrel performance.

The gotchas then become brass and primer flow, and perhaps a little more sensitivity in gas-operated mechanisms.
You don't get a whole lot smaller than 9.6mm... which is what I am using.
The 6xc is mostly used for competition but competition that includes rapid fire stages, unlike similar cartridges like the 6BR. Note the similarity in the tubb2k and the ar15.

I wasn't trying to say it's the answer to whatever problem you've got. I'm just saying it would be a good case to start from. Or go back and look at the cartridge it was made from which iirc is the 220russian.
Yeah, but that case almost guarantees a PPR (pounds per round) of .033 or greater. I am shooting for a .029 PPR or better.

You don't get a whole lot smaller than 9.6mm... which is what I am using.

I remember seeing a picture a while ago of a round somebody was working on for the M-16 platform. It looked like a 25ACP case stretched out to 45mm, loaded with .224" bullets, pretty much straight walled.

I remember seeing a picture a while ago of a round somebody was working on for the M-16 platform. It looked like a 25ACP case stretched out to 45mm, loaded with .224" bullets, pretty much straight walled.
I think that's the Knox Engineering prototype round.
It's got performance equal to 5.56 NATO, or so they claim.
I have investigated 8.0mm case heads, and smaller.
But I will stick to currently achievable powders.
Anything with a 9.6mm base is gonna have a pretty low impulse, anyway.

nolo, just curoius, where do you get all this info, sorry this is off topic, but i would like to get in on this, and currently know about nothing. thanks

Maybe I missed it somewhere but why not neck the Grendel to the bullet size that you want? It has a 4gr. powder advantage to the 222 Remag and would seem to be ideal for your application.

NCsmitty

nolo, just curoius, where do you get all this info, sorry this is off topic, but i would like to get in on this, and currently know about nothing. thanks
PM me, and explain.
Maybe I missed it somewhere but why not neck the Grendel to the bullet size that you want? It has a 4gr. powder advantage to the 222 Remag and would seem to be ideal for your application.
You did miss it:
Yeah, but that case (.220 Russian, the same case as the Grendel) almost guarantees a PPR (pounds per round) of .033 or greater. I am shooting for a .029 PPR or better.

Alright, the latest:
I am highly considering a .222 Remington necked up to 6mm and trimmed to 42mm, firing an 85-95 grain bullet.
This gets awfully close to 6mm-.223 territory, but should offer OAL advantages with the longer, heavier 95 grain bullets that I am very interested in.
I have heard anecdotal data of the 6mm-.223 having a velocity range of 2450-2800 fps, but no bullet weights associated with that data (obviously, heavier bullets would be slower).
I would LOVE to shove a 90-ish grain bullet at 2750 fps with this new cartridge, but I am not sure that's really feasible.
Any input?

I had a little history on that in Post #16.

Sam Fadala said the 6mm-222 with 87 grain bullet would equal the .250 Savage at 200 yards because of the higher sectional density of the 6mm bullet vs .257. That is about as close as you are going to get with a common current case and without physical testing.

I had a little history on that in Post #16.

Sam Fadala said the 6mm-222 with 87 grain bullet would equal the .250 Savage at 200 yards because of the higher sectional density of the 6mm bullet vs .257. That is about as close as you are going to get with a common current case and without physical testing.
Interesting.
Do we know what a .250 Savage looks like at 200 yards?

At this (http://www.gunnersden.com/index.htm.250-3000savage.html) link, at the bottom, we can see some data for 100-grain bullets out of the .250 Savage. By reverse-engineering the energy we get at 200 yards, it looks like it's under 2400 fps.
Using that as a stepping stone, I think the velocity range we're gonna see for 95 grain bullets for the 6x42mm is gonna be something like 2600 +/- 75 fps.
Not bad, but I'd like that to be 2675 +/- 75 fps.
Hmmm... Think my estimates are correct?

All of this speculation is interesting. But selecting a non standard bore diameter is going toi seriously inhibit any experimentation. Who is going to make your bullets? Who is going to rifle your barral? A custom mandrel or button, all the tooling time... I think you would spend your time better designing a new .224. Or 6mm, .257, or 6.5mm bullet.

There's not much new under the wildcatting sun. Hornady is doing some interesting stuff with their double base light magnun powders.

All of this speculation is interesting. But selecting a non standard bore diameter is going toi seriously inhibit any experimentation. Who is going to make your bullets? Who is going to rifle your barral? A custom mandrel or button, all the tooling time... I think you would spend your time better designing a new .224. Or 6mm, .257, or 6.5mm bullet.

There's not much new under the wildcatting sun. Hornady is doing some interesting stuff with their double base light magnun powders.
The 5.85mm caliber has already been put on the backburner in favor of the 6mm.
However, we could still use 5.85mm if we wanted to, as has been said before, the caliber has been used before.
But... After looking at it for a while... the 6mm seems best for this project.

Nolo, were you aware that Hodgden has load data for the 6mm-222 at their site?

NCsmitty

Please excuse the typos. I am on a blackberry keypad.

Nolo, were you aware that Hodgden has load data for the 6mm-222 at their site?

NCsmitty
No.
No, I wasn't.
That would have made this a lot easier...
Hmmm...
Why do I always come up with stuff that exists already?

Sorry about missing the caliber change. Keep us posted on the tests! I think I am going to have a 220 swift chamber cut into a fast twist barrel eventually. That is as custom as I want to get right now!

6mm-222 jpg specs.


NCsmitty

Oh...
Neato...
Lookee here:
Bullet: 85 GR. SPR SP
Powder: BL-C(2)
Bullet Diameter: .243"
OAL: 2.260"
Charge in grains: 22.5
Velocity: 2742 fps
Pressure: 49,600 CUP
I wonder...
If we bumped the pressure up to 52KCUP (PSI), and bumped the bullet weight up to 95 grains, could we maintain the velocity?
Cut the neck back to a more reasonable length, Use a Sierra MatchKing 95 grainer... It's BC is awful close to the 123-grain Lapua Scenars (.527 versus .547)...
Even 2700 fps would still be wonderful, giving us the range (or better) of the 6.5 Grendel inside our weight requirement. Not to mention our critical range would be killer (300+ yards)*
Wow.
This may be it.
Doing some moving of the measurements, with the kind of neck I want, the shoulder advances forward a tad, which should help performance.
*I define critical range as the range at which the velocity drops below fragmentation range. For most of those match bullets, that is around 2050 fps.

Sorry about missing the caliber change. Keep us posted on the tests! I think I am going to have a 220 swift chamber cut into a fast twist barrel eventually. That is as custom as I want to get right now!
No problem. I'm excited now. This caliber looks VERY promising.

Photoshopped goodness of the new round:
http://i200.photobucket.com/albums/aa149/Nolo_photo/6x42mm.png
6x42mm

A 6x42 based on the .222 case is a beautiful little cartridge. Too good, in fact, to have been overlooked (Bill Alexander, Stan Crist, and others, I'm sure, have done it or proposed it).

Sierra's relatively new 6mm 95gr SMK would be a perfect match. You'd have to calculate, however, whether a max AR mag-length load of, oh, 2.265" would require a case trimmed to 41mm or 41.5mm, instead of 42mm. I calculated it once, but now can't recall what it was.

Somewhere in my notes I've got from Sierra themselves the exact dimensions of the 6mm 95 SMK, which would be needed to calculate the maximum case length.

If I were designing a 6x42, it would have the short neck of the .223 instead of the longer of the .222. I'd also give it a 30-degree shoulder for a hair more powder. We've found in the 6.5 Grendel that it doesn't affect full-auto feeding at all.

But as others have mentioned, this is sort of water under the bridge, because it wouldn't be revolutionary or different enough from existing 5.56 for military interest. But at least one would have the satisfaction of owning the cartridge the 5.56 should have been, and a great little deer round.

If it were a commercial cartridge, I'd get an AR chambered in it. Oops! Did I say that??? :D ;) :evil:

John

Don't get all mesmerized by the high BC match bullets if you are contemplating a military caliber. The army will surely want some AP capability, will stick to FMJ for Hague Convention feelgood, and will emphasize harsh conditions feeding over a needle nose. I figure that will cost several points on BC and will affect downrange performance in a gun meant to outperform the current crop of assault rifles.

Valid concerns, Jim, but I think they can be addressed.

If the 6x42 were to be a serious contender, I'd develop an FMJ with the same exterior shape or form factor as the 6mm 95 SMK. Then the military would have an FMJ and an OTM, similar to M855 and Mk262.

I don't think military use prohibits a "needle-nose." Consider, for example, the Russian 5.45x39; it has a high BC projectile and yet as careful as the Russians are about reliability in combat conditions, they didn't opt for something with a stubbier ogive.

Even the 7.62 147gr FMJ of our own 7.62x51 NATO M80 could hardly be more "pointy," I'm looking at a de-linked sample on my desk right now.

John

P.S. A longish projectile is exactly what one wants to maximize the AP capability of a long, high-sectional density penetrator "payload."

If I were designing a 6x42, it would have the short neck of the .223 instead of the longer of the .222. I'd also give it a 30-degree shoulder for a hair more powder. We've found in the 6.5 Grendel that it doesn't affect full-auto feeding at all.
Which, I might note, is exactly what I did (Okay, I kept the .223's shoulder, I honestly don't think that it will affect performance by enough of a margin for me to really care.)
Don't get all mesmerized by the high BC match bullets if you are contemplating a military caliber.
Since, in the final incarnation, I intend to use a bullet of my own design and not an SMK, I don't think that'll be a problem.
Somewhere in my notes I've got from Sierra themselves the exact dimensions of the 6mm 95 SMK, which would be needed to calculate the maximum case length.
If you could dig those up... That would be awesome. Just based on my guestimates, it should work.
But as others have mentioned, this is sort of water under the bridge, because it wouldn't be revolutionary or different enough from existing 5.56 for military interest. But at least one would have the satisfaction of owning the cartridge the 5.56 should have been, and a great little deer round.
No, but like I mentioned, it'd make a great springboard for a family of caseless cartridges.
I figure that will cost several points on BC and will affect downrange performance in a gun meant to outperform the current crop of assault rifles.
Probably not if the bullet is well-designed.

Well, I'm just wondering why you started out talking about a deuce with a .223 neck - dude, they shoot the same size bullets... And I've shot with the guy who invented the deuce.

If you want a thing to chuck heavy .223 bullets... Look at the ballistics for what's already out there... Odds are you'll be looking at an overbore situation. A .22-250 should do it. A .220R or .22PPC will do it, but you can't cram as much powder in.

You're going to run into a pressure curve problem with this concept - You need enough pressure to get the thing going, but with that heavy a bullet, and a powder fast enough for a smaller case, you're going to spike beyond the brass strength before you really get things going. You need enough case capacity to use LOT of a slower powder.

Well, I'm just wondering why you started out talking about a deuce with a .223 neck - dude, they shoot the same size bullets... And I've shot with the guy who invented the deuce.
Uhhh... because the Triple Deuce's case is shorter, which gives me extra room to use extra-heavy bullets in a 57.5 OAL.
I have since moved on from that, though.
If you want a thing to chuck heavy .223 bullets... Look at the ballistics for what's already out there... Odds are you'll be looking at an overbore situation. A .22-250 should do it. A .220R or .22PPC will do it, but you can't cram as much powder in.

You're going to run into a pressure curve problem with this concept - You need enough pressure to get the thing going, but with that heavy a bullet, and a powder fast enough for a smaller case, you're going to spike beyond the brass strength before you really get things going. You need enough case capacity to use LOT of a slower powder.
I only wanted to chuck them at 2550 fps, and ran into pressure problems, anyway.