This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons.
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"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."
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.
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
"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.
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%.
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%.
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.
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.
Yes, it' very similar to (but probably better than) the 7,62x43 "neckless" I made years ago with a shortened aluminium/plastic case of blank ammo.
The involvement of Beretta is interesting, a few month ago their head of product development told me they were working on a different rifle than the ARX series, so maybe there's a link to investigate.
A little bit more on SIG:
Best photos so far of their cartridge and case design:
"SIG opted for a bi-metallic, multi-piece case instead of a telescoping polymer case. During testing, SIG learned that it’s difficult for polymer rounds to keep high pressures. As of December 2018, SIG has demonstrated at two separate locations for the U.S. Army the 6.8mm Hybrid ammo shot from a 16-inch barrel at 3,000 feet per second.
One of the many benefits of SIG’s Hybrid ammo is that it can be used in legacy firearms. For the regular consumer, this translates to access to high-pressure, high-velocity rounds in the future that we can use in the guns we already own. For competitors, Lindsay Bunch, of the Strategic Weapons Group, likens the increased performance of the hybrid ammo to getting 24-inch bolt gun velocity in a 16-inch gas gun."
Most interesting is a look into their .338 LWMMG, of which their NGSW LMG is based upon. This gives some hint as to how it works:
"The SIG SAUER Lightweight 338 Machine Gun is their answer to a USSOCOM Request for Information solicitation for a Lightweight Medium Machinegun (LWMMG), which should replace the M240. SIG says this 338 is the big brother to the machine gun that will be submitted for the NGSW-AR solicitation to replace the M249. The machine gun has been developed by an engineer with more than 30 years of experience building machine guns — it’s his specialty. Weighing under 20 pounds, the 338 Norma Magnum machine gun fires a bullet at 2,650 feet per second out of its 24-inch barrel and that projectile is still supersonic at 1,500 yards. And it has a cyclic rate of 500 to 600 shots per minute. We’d expect a magnum caliber to have quite a bit of kick, but the SIG team says the unique recoil design produces less felt-recoil than a 308 Winchester. To put it into perspective, the SIG MCX, chambered in 5.56, puts 2 foot-pounds of energy into your shoulder, while the SIG .338 machine gun delivers 3 to 4 foot-pounds of energy to the shooter’s shoulder, according to SIG engineers."
Seeing how Mauser is still living off the royalties it got off the US prior to WW1, you should sue. Your great-great-grandchildren will thank you.;)
Farmplinker said...Seeing how Mauser is still living off the royalties it got off the US prior to WW1, you should sue. Your great-great-grandchildren will thank you.;)
I already helped the USMC to save several millions of US dollars, my employer is going to think that I'm working for Uncle Sam... :-)
Could you elaborate on "how Mauser is still living off the royalties it got off the US prior to WW1"? I doubt that the, at the time, very small U.S. Army played any significant role in Mauser income.
All that is left of "Mauser" is a brand name and a front company on the premises of Blaser at Isny which owns it. I fail to see any attempt to market something interesting since the M03 16 years ago.
The former Mauser factory at Oberndorf is now part of Rheinmetall. The Oberndorf management took pride in ordering scrapping (yes, scrapping, not selling) each and every precious small arms caliber test barrel they still had, for example.