In their booth at the recent AUSA show in Washington, DC, SIG Ammunition teased additional caliber options for their composite case ammunition technology recently selected by the US Army as the Common Case Architecture for the Next Generation Squad Weapon program.
Initially developed in 6.8x51mm for NGSW, the cartridge features a two-piece case which combines a steel head for strength with a more brass case. The same technology is used in the commercial round named .277 SIG FURY which received SAAMI approval two years ago.
According to Jason Imhoff, Chief Technology Officer and Vice President of SIG Ammunition, they’ve concentrated on expanding the capability quite a bit with 6.5 Creedmoor and 7.62 NATO, but other calibers are also in the works. So far, they are seeing 300-500 fps increase in velocity over standard case designs.
Seen here are 5.56mm, 6.5 CM, 6.8 CCA, 7.62mm and .338 Norma Mag which are military calibers currently in use. Others, including SIG FURY versions of popular hunting and sporting cartridges will be pursued as well.
Is the expectation that this new case head and increased pressure combination be backwards compatible with existing firearm chambers (ie legacy 308 or 6.5) or only for new bolt/chamber specifically approved for the changes?
HA! I knew it!!
The M5 light totally telegraphed this. I bet well see a M5L 556 high pressure replace the M4 and the M5H 6.8 will become a DMR
The issue I imagine is backwards compatibility in weapons that may not be able to handle the pressure.
Dropping a 80kpsi cartridge into an unmodified semi auto tuned for 55-62kpsi cartridges? That would be awesome if it works, but it seems optimistic?
I think developing a new class of purpose built high pressure cartridges, which also have COL suitable for VLD projectile shapes, would be more promising.
A 6mm, using the SIG 5.56 case, firing a 85gr VLD @ 3000fps from a 16″ barrel, in an intermediate size 2.5″ COL weapon (think AR12 / LWRC Six8 concept.) That would have a 30rd firearm with 7.62×39 recoil, but vastly greater effective range than 5.56 and likely equal or better range than 6mm ARC.
Or a .204 VLD 50gr lead free ‘5×42’, also based on the SIG 5.56 case, firing at 3400+fps, designed to fit into the AR15 2.25″ COL. That would greatly exceed 5.56 or 5.45 ballistics, while keeping recoil and ammo weight comparable to 5.56.
These would be fantastic cartridges, without the liability concern of dropping a high pressure cartridge into legacy weapons not capable of handling these higher pressures.
Have you been the conversations I’ve been having with others over the past few months?
No, this is my first comment on the subject.
I take it others had similar ideas?
Welp. Off to the search tab to see if I can find them for me I guess.