[jmr40]

Both the 7.62X51 and the M14 were failed experiments as general purpose military rounds. The 7.62 round has it's place as a designated marksman round or as a short range snipers round. But the 5.56 we have been using for the last 50 years is just fine for most situations.

No cartridge nor platform to fire it from is perfect in every situation, but I'm certain we'd have filled more body bags in the last 50 years if we'd stayed with the 7.62 round.

It maybe possible to develop something in 26 or 27 caliber that improves on 5.56 without the negatives of 308. But I have serious doubts. In order to get the muzzle velocity with bullets they want to use you're going to have to very serious negatives. The laws of physics are strictly enforced, there is no way around it

#1 That much velocity, with that much bullet weight, from an AR 15 platform is going to generate as much, of not more recoil than you'd get from the much heavier M14/308 combo. Reducing recoil was a big part of the decision to drop the 7.62 round.

#2 To get the desired velocity is going to require light for caliber, short stubby bullets. While the MV looks good, that type bullet will lose velocity quickly limiting long range effectiveness. It also means poor penetration, especially on barriers. Those were 2 alleged negatives of the 5.56 round.

Unless the military had developed some type of mystery round that defies the laws of physics I don't see any advantage with any of the 6.5 or 6.8 cartridges that can't be solved by 70-77 gr bullets in the 5.56.