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; 522173 views.
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
poliorcetes

From: poliorcetes

7/9/19

How a suppressor can reduce recoil by 45%?

 

I mean, blowed gas are responsible of a minor part of recoil. A suppressor eliminates reaction forces caused by gas, but it is not used as a counter-recoil force against recoil direction like a muzzle brake does diverting gas at high speed

gatnerd

From: gatnerd

7/9/19

"I mean, blowed gas are responsible of a minor part of recoil. A suppressor eliminates reaction forces caused by gas, but it is not used as a counter-recoil force against recoil direction like a muzzle brake does diverting gas at high speed."

Gas is responsible for like 50% of the recoil of a rifle.

https://www.thetruthaboutguns.com/ar-15-muzzle-brake-shootout-3/

Muzzle devices can have a profound effect on recoil. In 5.56, the dead air sandman suppressor reduces recoil by 46%. The best muzzle break reduces it by 78%, but with intollerable levels of blast. 

The Surefire Warcomp, the ideal military compensator/flash hider, cuts recoil by 35%.

 

EmericD

From: EmericD

7/9/19

poliorcetes said...

I mean, blowed gas are responsible of a minor part of recoil. A suppressor eliminates reaction forces caused by gas, but it is not used as a counter-recoil force against recoil direction like a muzzle brake does diverting gas at high speed

For handguns, yes, but for rifles powder load is a substantial part of the recoil.

For example, let's take the 7.62 mm NATO M80 (9.5 g bullet at 850 m/s, and a 2.9 g powder load).

The impulse produced by the bullet alone is 9.5*.85 = 8.1 N.s, when the total impulse as measured on a ballistic pendulum is 11.6 N.s, so the gases are producing ~30% of the total recoil, that is 2.9 g of powder with an speed of ~1200 m/s.

The conical muzzle brake on the Lee-Enfield "jungle carbine", while very effective to dissipate the muzzle flash, acted like a rocket-engine nozzle and increased the recoil impulse by 10%.

Wessels3

From: Wessels3

7/9/19

What it basically comes down to is that the recoil of a hot 6.8mm round will not be a problem. The weapon system will not be very light, with lights, sights and lasers stuck on it, as well as a suppressor. The weight helps to reduce recoil and then there is the suppressor, as you showed, which also reduces recoil. And, of course, the suppressor reduces the other issue with hot rounds, i.e. muzzle blast and flash.

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