New Army "Caliber Configuration Study"

[Tony Williams]

Update on the Polymer ammunition. It's garbage, and HANKA's suspicions were spot-on.

Correction: PCP ammunition may be garbage, but the .50 cal MK323 Mod 0 from MAC LLC has been successfully undergoing independent tests in different machine guns and is in the process of getting qualified for use by the USMC. It is a more conservative design than the PCP, with a relatively large brass base, but still saves 23% of the overall cartridge weight.

[Tony Williams]

Are there any new developments in caseless ammo? The last I heard about was with the HK G11 and that was about 30 years ago.

The US Army's LSAT project (Lightweight Small Arms Technologies) for a 5.56mm MG and ammo to be made as light as possible resulted in two parallel development tracks: for caseless telescoped and plastic-cased telescoped ammo. The pic below shows the caseless (red) and plastic-cased ammo belts next to the usual brass 5.56x45.



An HK info package on G-11 caseless ammo was bought in order to speed up development, but even so it has been problematic due to the host of problems which bedevil caseless rounds. Around 90% of the development has been on the plastic-cased variety. This seems to work reasonably well, but funding has been reduced to a trickle.

[stanc]

fyi

Guardsman26 wrote:

A lot of very interesting discussions are taking place about what the US Army's Caliber Configuration Study (CCS) means for industry. The US Army's Marksmanship Unit (USAMU) has helped focus the development, testing and evaluation of prospective new calibers for the Combat Lightweight Automatic weapon System (CLAWS) program by independently developing two rounds (discussed elsewhere on this forum). One is a 6.5 mm round designed to fit within the action length of 5.56 mm. The other is a 6.5 mm round designed to fit within the action length of 7.62 mm.

Only the second of these two rounds is cable of comfortably exceeding 7.62 x 51 mm NATO performance in a lighter package. But, and it's a big but, the smaller 6.5 mm round that fits within a 5.56 mm action length makes it very easy to upgrade legacy weapons with a new upper, rather than buying millions of new guns. As Tony will immediately point out, unless you exceed 7.62 mm performance, you will need to keep 7.62 mm weapons. However, since 7.62 mm weapons are likely to be replaced through the larger caliber Lightweight Dismounted Automatic Machine Gun (LDAM) program, we could see something like a .338 DM / Sniper weapons used for long range work as well as large caliber GPMGs. So matching 7.62 mm performance may be less of an issue than we originally thought.

The economic argument may therefore favour a smaller 6.5 mm round, although that is not my preference. The smaller round is essentially a militarised Grendel and still delivers excellent long-range performance.

What is incredible and what seemed impossible only a few years ago may well become a reality: this could mark the beginning of the end for 5.56 mm NATO. That is definitely a step forward in my book.

http://forums.delphiforums.com/autog.../?msg=5556.697

[Trooper]

The advantage of the 6.5mm (.260) and the 8.59mm (.338) have similar BC (.600) and SD. From what I have read, there is shift towards something heavier. I do like the idea of 6.5x45.

[Guardsman26]

Hey, Stan, thanks for quoting me! (I must be doing something right.)

My prediction is that we'll see a proper military spec lead-free 6.5 mm bullet developed for the Grendel 6.5 x 39 mm case and also for a necked-down 7.62 x 51 mm case. How this performs. Assuming it has a steel core and is mounted in a copper shoe (as per the RUAG / NAMMO 5.56 and 7.62 lead free designs) it would weigh around 7 grams or 115 grains. It may not quite match 7.62 mm exactly, but it could still deliver excellent 600 m plus performance and that may be enough.

Two important advantages of a lead-free round is that it would provide superior penetration of body armour than a regular lead core round. It would also be cheaper to manufacture. Assuming it could be designed to yaw reliably when penetrating soft tissue (like the RUAG / NAMMO lead free designs which move centre of gravity rearwards to allow this), the bullet would need need to fragment to be lethal like 5.56 mm M855. No Geneva / Hague Convention problems would speed up approval.

While the merits of a round that fits legacy weapons are hard to argue against, I still like the idea of an optimised case with growth potential that allows both tracer rounds to be fitted and an eventual move to polymer technology.

As the CCS gets underway, you gotta say hats off to Bill, Arne and Janne for setting the bar so high with the Grendel as is.

[stanc]

My prediction is that we'll see a proper military spec lead-free 6.5 mm bullet developed for the Grendel 6.5 x 39 mm case and also for a necked-down 7.62 x 51 mm case.

As in 6.5x47 Lapua?

While the merits of a round that fits legacy weapons are hard to argue against, I still like the idea of an optimised case with growth potential that allows both tracer rounds to be fitted and an eventual move to polymer technology.

Yes, the probable reduction in powder capacity with a polymer case does argue for a cartridge case longer than that of 6.5 Grendel.

It should be interesting to see what comes out of the CCS. Any word on when that study is to conclude?

[NugginFutz]

As in 6.5x47 Lapua?

Yes, the probable reduction in powder capacity with a polymer case does argue for a cartridge case longer than that of 6.5 Grendel.

It should be interesting to see what comes out of the CCS. Any word on when that study is to conclude?

THANK YOU. Finally, something really interesting to read...

[stanc]

6.5x43 GPC prototype, second from left, below.



Article: http://www.thinkdefence.co.uk/2013/1...ange-calibres/

"...the US discovered that various potential enemies have been quietly enhancing their own small arms capabilities and are on the verge of achieving overmatch.

There has been no specific information on what the evolved threat is, but it appears that the Chinese and Russians are about to field improved ranges of weapons and ammunition."

Maybe there really is a 6.5 Grendelski???

[cory]

I'm assuming that 6.5x43mm GPC case is a 6.8 spc resized, correct? Anybody know what the case capacity would be for it?

[stanc]

I'm assuming that 6.5x43mm GPC case is a 6.8 spc resized, correct?

Nope. It may not be obvious in the photo, but the 6.5 GPC is essentially a "stretched" 6.5 Grendel. Same basic case, same diameter, just a few millimeters longer.

[JASmith]

I don't remember for sure, but wasn't there a case drawing on one of the other forums?

[cory]

Nope. It may not be obvious in the photo, but the 6.5 GPC is essentially a "stretched" 6.5 Grendel. Same basic case, same diameter, just a few millimeters longer.

Where did you get that information from? I mean I prefer you're correct, but would that not be an expensive prototype?

[cory]

Let's see 39mm to 43mm is a 10% increase in capacity. Using LRRPF52's data using 123 AMAX and CFE223 in a 14.5" barrel, http://www.65grendel.com/forum/showt...6-quot-Grendel
31.1gr 2489 fps
31.4gr 2520 fps
31.7gr 2532 fps
32.0gr 2553 fps
32.3gr 2572 fps
32.6gr 2598 fps
32.9gr 2612 fps

Increasing 31.1 gr by 10% is 34.2gr and increasing 32.9gr by 10% is 36.2gr. Interpolating from the known data, 34.2gr would result in 2700fps and 2828fps. Now these calculations are elementary at best, but I think we could expect a MV in that range. If we were to see the military develop a canister powder I think we might see a MV in the 2800fps.

What say y'all am I completely off.

On a side note, I'd like to see how H4350 worked in that case.

NOTE: Interpolating outside the boundaries of known data will skew the results to some degree.

[stanc]

Where did you get that information from? I mean I prefer you're correct, but would that not be an expensive prototype?

Since Cris Murray's 7x46 UIAC has similar case dimensions, and reportedly the original development was done using 7.62x45 Czech brass, I'd imagine the cost of prototyping the 6.5x43 shouldn't be much different than similar wildcats. That's just a guess, though.

As for source of the info, I regret that I'm forced to play the confidentiality card. Sorry. However, if you can measure the images in the photo, you'll see that the GPC case has the same diameter as the Grendel case, not the slightly skinnier SPC case.

[stanc]

Let's see 39mm to 43mm is a 10% increase in capacity.

Interpolating from the known data, 34.2gr would result in 2700fps and 2828fps. Now these calculations are elementary at best, but I think we could expect a MV in that range. If we were to see the military develop a canister powder I think we might see a MV in the 2800fps.

What say y'all am I completely off.

I think your numbers are in line with calculations on Tony Williams' MG&A forum. FWIW, consensus there is that a lead-free, military ball projectile would likely weigh no more than 108-112 grains. (The steel-core FMJ bullet of Wolf's steel cased ammo is reportedly 110 grains, which seems to confirm that idea.)