Third Generation Battle Rifle

[Trooper]

Battle Rifle: Chambered in 7.62 NATO
Assault Rifle: Chambered in an Intermediate Cartridge

There's over a decade of 7.62 NATO and 5.56 NATO ammunition in stock currently. That is one of the biggest driving factors in what chamberings will be used.

That is the problem. We stuck with an outdated caliber instead of going to the 7x43 (.280 British). Then we went to a very light caliber, in a carbine rifle instead of a battle rifle. We are ignoring this huge hole in between the two calibers. Everything shows that the best caliber is somewhere between 6.5 and 7 mm. The 6.5mm is the sweet spot, with 7mm being the upper limit. The real question is do we stay with the limits of the M16 magazine well or go with a larger case? The goal would be to have a cartridge that could shoot a 6.5mm bullet (140 gn) at a muzzle velocity of 2500 f/s with about 2500 lb-lbs of energy. What size case could provide that? If we go to a 7mm then the bullet would have to be about 162 gn thus more recoil. A .308 bullet would need to be 192 gn to give similar performance.