gatnerd

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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NGSW Phase 2 Consolidation and info   Small Arms <20mm

Started 30/8/19 by gatnerd; 520987 views.
Farmplinker

From: Farmplinker

6/9/19

If it does take box mags, will it be more reliable than the M249 with box mags?

gatnerd

From: gatnerd

6/9/19

"Good weight tabulation.  I am still amazed by the "all up" weight of M4 variants, but I guess that's because my military service was with the M1 carbine and M16A1 rifle."

Yes, once you start adding accessories weight definitely goes up. My personal rifles, its quite noticeable at first the change between what came out of the box, vs what it weighs with optic / light / sling. On the other hand, once you get used to it, its less noticeable. 

Looking at weight of accessories, it does show the advantage of starting with as light a base rifle as practical. 

 

"Question on the 6.8 NGSW cartridge weight:  Why assume 20% less than 7.62 M80A1?  I'd think there would be negligible difference, since the 6.8 bullet is 5 gr heavier."

I was being charitable, giving a best case. 

But I agree with you, I expect SIG's offering is going to be pretty close / identical to existing 7.62 Brass. The projectile is about the same, the case is about the same, its likely to have a bit more powder then 7.62, and I just can't figure out how a Steel + Brass case is going to be much lighten then a regular brass or steel case. 

gatnerd

From: gatnerd

6/9/19

"If it does take box mags, will it be more reliable than the M249 with box mags?"

No idea. 

On the one hand, this and the .338 its based on are SIG's first real machine gun design. Whereas FN had decades of MG experience and still had issues with the M249 when it was introduced. 

On the other hand, modern firearms are now designed with sophisticated computer programs that allow running various simulations of the action / stress analysis / myriad other tests. So its possible the SIG LMG has a really good design right from the get go. 

In general, based on their pistols and rather notorious QC issues with their civilian weapons, I'm skeptical of SIG. 

 

In reply toRe: msg 55
gatnerd

From: gatnerd

6/9/19

True Velocity is now showing off their 6.8 NGSW Cartridge:

True Velocity composite-cased ammunition has been selected for the U.S. Army’s Next Generation Squad Weapon (NGSW) modernization program. True Velocity’s 6.8mm composite-cased cartridge was submitted as part of an overall NGSW weapon system in partnership with General Dynamics Ordnance and Tactical Systems and firearm manufacturer Beretta Defense Technologies.

True Velocity’s proprietary 6.8mm case design will provide end users with significant logistical and operational advantages over traditional brass-cased ammunition, including substantially increased effective range and muzzle energy, drastic reduction in cartridge weight and enhanced accuracy. The combination of True Velocity’s ammunition with the General Dynamics OTS weapon submission results in a state-of-the-art weapon system capable of long-range lethality, short recoil impulse, significant ballistic improvements and enhanced operational effectiveness for the soldier.

“True Velocity’s 6.8mm composite case design produces a level of performance, consistency and efficiency never before seen in small arms ammunition,” said Chris Tedford, president and chief operating officer for True Velocity. “Combining True Velocity’s innovation and technology with the expertise of General Dynamics OTS and Beretta results in a weapon system solution that exceeds NGSW requirements and provides the U.S. Army with a definitive edge on the field of battle.”

http://soldiersystems.net/2019/09/06/us-army-selects-true-velocity-composite-cased-ammunition-next-generation-squad-weapon/

  • Edited 06 September 2019 21:43  by  gatnerd
poliorcetes

From: poliorcetes

6/9/19

Is beretta doing for GD what HK is doing for Textron?

 

And the foto is really interesting. What a tiny shoulder!

nincomp

From: nincomp

6/9/19

It is actually very much like the 7.62x43 neck-less round on pages 117 and 118 in Emeric's "Towards a "600 m" lightweight General Purpose Cartridge, v2019, Full Paper."

https://www.researchgate.net/publication/335004124_Towards_a_600_m_lightweight_General_Purpose_Cartridge_v2019_Full_Paper

A few years ago I was very proud of myself for thinking up a neckless polymer round that could be used in weapons designed for traditional metallic cartridges.  When I discussed it on this forum, Emeric posted that it already existed but he couldn't talk about it until the patents were granted.  At least I knew that I had an idea that wasn't stupid, for once.  I just had it too late.

  • Edited 06 September 2019 23:22  by  nincomp
Red7272

From: Red7272

6/9/19

gatnerd said...

Emeric, do you need to sue?

This looks very similar to something he showed us years ago. Polymer case with a thickened shoulder that was glued to the projectile. It would make long ogive version of existing round possible.

In reply toRe: msg 59
gatnerd

From: gatnerd

7/9/19

It also appears similar to this 25x145mm exerimetal polymer/neckless case:

http://www.quarryhs.co.uk/tankammo5.html

In reply toRe: msg 60
Wessels3

From: Wessels3

7/9/19

Just for interest sake, the recoil energy of a few relevant rounds:

The MARS/Cobalt 6.8 cartridge: 14.0 kg.m/s. 140 grains at 3200 ft/sec., using an estimated 56 grains of propellant: 15 kg.m/s. 

30-06:             12.3 kg.m/s.  (150gr at 2800 ft/sec + 50gr of propellant)

7.62 NATO:      11.6 kg.m/s. (150gr @ 2700 ft/sec + 45gr propellant)

The 6.8 cartridge has about 14% more recoil than the 30-06. We know that the second model FG42 was "reasonably" controllable on full-auto, with a cartridge similar in power to the 30-06. It did have an efficient muzzle brake though, and a well designed stock.

gatnerd

From: gatnerd

7/9/19

"Just for interest sake, the recoil energy of a few relevant rounds:

The MARS/Cobalt 6.8 cartridge: 14.0 kg.m/s. 140 grains at 3200 ft/sec., using an estimated 56 grains of propellant: 15 kg.m/s. 

30-06:             12.3 kg.m/s.  (150gr at 2800 ft/sec + 50gr of propellant)

7.62 NATO:      11.6 kg.m/s. (150gr @ 2700 ft/sec + 45gr propellant)

The 6.8 cartridge has about 14% more recoil than the 30-06. We know that the second model FG42 was "reasonably" controllable on full-auto, with a cartridge similar in power to the 30-06. It did have an efficient muzzle brake though, and a well designed stock."

Good info.

In terms of recoil, its worth noting that suppressors reduce recoil by ~25-45% depending on suppressor and cartridge.

One .308 test:

With a 25% recoil reduction, it would be 10.5kg/ms

33% = 9.38 m/s

Then there's also the effect of hanging a 1lb metal tube on the muzzle, which should certainly help to reduce muzzle climb. 

  • Edited 07 September 2019 8:58  by  gatnerd
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