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Military Guns and Ammunition

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This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons.

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An interesting point of NGSAR PON   Small Arms <20mm

Started 9/9/18 by poliorcetes; 5229 views.
In reply toRe: msg 35
gatnerd

From: gatnerd

9/10/18

Also, we have some input from GS5414, who was involved with the Airforce IMR Blue program, and is pretty plugged in with US Small Arms acquisitions.

His general thoughts on the program:

They have let go a little bit of the velocity spec but it still doesn't matter. This is well past the line of stupid. There's so much wrong with the program that I literally don't know where to start, and some things I just can't say. 

This is what happens when the US Army is allowed to blow $500M (no, that's not a joke) on a SAAC study and throw money at Lake City. 

Hit rates are bound to go down a bunch, cube space required for ammunition (6.8X51CT) increased, barrel life decreased over both scenarios, auto rifleman remain the slowest elements in the team because Army leadership isn't placing reasonable weight and size limitations on the weapon from the get go, on and on. 

They have dialed the spec back a bit for the time being, basically attempting to shoehorn in some stuff, and they will (I believe) continue to downgrade requirements until someone can reasonably do it.

The whole thing is a mess one way or another. 

The whole thing is a catastrophe. Even the Marines don't want a part of it now. I have serious doubts they'll get what they want out of this unless they continue to downgrade requirements to meet reality. 

 

In regards to LSAT:

Especially with an elimination of reciprocating action (CT cases), that's a hell of a lot of energy the shooter will absorb directly, not to mention the weapon itself. It's like giving your average untrained soldier a compact 7mm RUM bolt gun. You think that's going to buff out in any way, shape, or form?

In whether this will be a belt fed LMG or Mag Fed IAR:

Army (G8, not OPFOR) preference is for a belt fed LMG to fill the gap left by divestment of the M249 SAW. 

Opting for that over a magazine fed automatic rifle is going to lose them the support of another service... 

https://www.ar15.com/forums/General/Sig-s-NGSW-AR-and-NGSW-C-entry-for-the-M4A1-M249-replacement-underway-/5-2154023/?page=1

In reply toRe: msg 36
gatnerd

From: gatnerd

9/10/18

The last "data point" if we can call it that, is Trey Knight of Knights Armament, makers of the Knights 9lb 5.56 and 12lb 6.5 LMG.

Here he is, seemingly throwing his support behind CT:

http://soldiersystems.net/2018/10/09/trey-knight-asks-you-to-change-his-mind/

 

gatnerd

From: gatnerd

9/10/18

"It will fire at speeds that far exceed the velocity of bullets today, and it will penetrate any existing or known ... body armor that's out there," Gen. Mark Milley told Military.com at the 2018 Association of the United States Army's Annual Meeting and Exposition. "What I have seen so far from the engineers and the folks that put these things together, this is entirely technologically possible. ... It's a very good weapon."

Well, that should be interesting.

Wessels3

From: Wessels3

9/10/18

In what must be a unique development, bidders are being told to use a specific government-provided 6.8 mm General-Purpose bullet designated XM1186, but they can design their own cartridge to wrap around that bullet, provided that the result meets their performance specs. Those specs have not been revealed to the public, but a bullet weight of 125-130 grains and an MV of around 3,500 fps are rumoured.

The requirements seem to be insane to me! 6.8x130 grains at 3500 fps is practically unachievable in an automatic carbine. In a 16"barrel, muzzle blast, flash and noise will be stupendous, it will render any suppressor ineffective and will probably destroy it in no time. Recoil will be formidable unless the weapon is very heavy. 

autogun

From: autogun

9/10/18

Wessels3 said...

The requirements seem to be insane to me! 6.8x130 grains at 3500 fps is practically unachievable in an automatic carbine. In a 16"barrel, muzzle blast, flash and noise will be stupendous, it will render any suppressor ineffective and will probably destroy it in no time.

I have heard a rumour that the need to meet the ballistic requirements, coupled with a restrictive maximum overall length requirement, is virtually forcing candidates down the bullpup route. cool

 

poliorcetes

From: poliorcetes

9/10/18

THAT would be really something.

 

What about a clean slate of paper for designing the weapon? finally?

Wessels3

From: Wessels3

10/10/18

I have heard a rumour that the need to meet the ballistic requirements, coupled with a restrictive maximum overall length requirement, is virtually forcing candidates down the bullpup route. cool

A 130 grain bullet at 3500 ft/sec will require around 65 grains of propellant, I expect. The recoil impulse of the cartridge will be 16 Kg.m/s. For comparison, the 30-06 develops about 12.4 Kg.m/s and the 7.62x51 NATO develops about 11.7 Kg.m/s. In a 4.5kg rifle, the recoil energy of the rifle will be 28J! For the 30-06 it is about 16 J. To obtain that kind of velocity will require at least a 20" barrel, imo, more likely something like 22-24 inches. Obviously a case for a bullpup. The advantage with a conventional lay-out will be that the muzzle is further away from your face and a conventional, long-barrelled rifle would also allow the possibility of fitting a model m'07 bayonet which could be useful against sabre armed horsemen!

In reply toRe: msg 43
gatnerd

From: gatnerd

10/10/18

From the earlier comments from GS4154, he mentions that the velocity requirements have been lowered - and will likely continue to be lowered.  

So I think we're likely looking at something more like 3,300fps or less, rather then 3500.

gatnerd

From: gatnerd

11/10/18

"I have heard a rumour that the need to meet the ballistic requirements, coupled with a restrictive maximum overall length requirement, is virtually forcing candidates down the bullpup route."

 I think you may be right.

Since we don't have a 6.8 NGSAR round, or 6.8x51, I had a Quickload analysis done of 6.5 Creedmoor 123gr at 62,75, and 100 kpsi out of both 16" and 20" barrels. 

62kpsi

16”- 2795fps 

20”- 2962fps

 

75kpsi

 

16" - 2960 fps

20" - 3124 fps

 

100kpsi

 

16" - 3128 fps

20" - 3279 fps

 

Whats interesting is that across these, +4" of barrel is the equivalent of +13-25kpsi. 

 

62k/20" = 75k/16" velocity 

75k/20" = 100k/16" velocity 

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