For now it might be more useful to keep both the 5.56mm and 7.62mm NATO rounds. It may be cheaper in the long run to have only one cartridge, but by forcing the military to use only one cartridge, it could limit the tactical capabilities of the infantryman's weapons.

Each round has its benefits. I think that they complement each other very well. Tanks use different types of rounds depending on the target type, e.g. HE rounds for soft target and AT rounds for armored ones.

I think that a dismounted infantry squad needs to have both rounds for the best overall effectiveness. This could be done by assigning 1-.30 caliber SAW and 2-.30 caliber semiautomatic high capacity rifles to each squad, plus the usual M16 (.22 caliber) armed troops, while also receiving support from a vehicle mounted .50 caliber machine gun or 20mm cannon.

The 5.56mm cartridge is very efficient at wounding tissue at short range because light, high velocity bullets have a tendency to destabilize in tissue, making for wounds that may seem out of proportion to their caliber, but of course your mileage may vary. As a result of the light bullets used in the 5.56 cartridge, though, they are more prone to ricochet or under penetrate when used against vehicles, buildings, or other types of cover.

Penetration is where the 7.62mm shines. It doesn't tumble or fragment to the same extent as the 5.56 in tissue but it penetrates much better than the 5.56mm.

Some folks want to replace the 5.56mm outright with the 7.62mm, but I think that this would be a mistake. There are other alternatives available.

1. As already stated, use both cartridges to complement each other. Just as tanks use specialty ammo and the Air Force can call on specialized aircraft to perform specific roles, the infantry squad should be able to make use of both cartridges.

2. Convert to a caliber/cartridge (6.8mm SPC?) somewhere between the 5.56 and the 7.62 and then issue magazines with mixed bullet types (a mix of high velocity fragmentary and higher penetration rounds) in a ratio most appropriate to the mission type.

I understand that point of impact would change when firing bullets of different weights and velocities, but isn't that already the case with the ammo that we are using now? My magazine has two kinds of ammo in it right now; a slower, lighter tracer and a faster, heavier ball cartridge in a ratio of 1:2. Anti-aircraft guns mix HE, AP and tracer rounds without compromising effectiveness.

The ideal caliber, in terms of recoil, penetration and wound potential is probably somewhere between 6mm (.243") and 7mm (.284"). By moving to an intermediate caliber and using mixed ammo magazines, say 1-penetrator:2-frangible rounds, I think it might be possible to combine the strengths of both NATO rounds into one package.

I realize that the army is a very traditional organization, and that change is always resisted at all levels, but it is not because of tradition that we have the best military in the world; it is because of innovation. We adapt and we overcome. Tradition makes us the best soldiers but innovation makes us the best equipped.

Conclusion

To survive, we need to be able to adapt. There are two ways to make a squad adaptable: through the use of two complementary specialists, giving tactical flexibility at the squad level, or by incorporating a multi-role round, providing for tactical flexibility at the individual soldier level.

The Air Force has struggled with the use multi-role aircraft vs. the use of complementary specialized aircraft, and it appears that they are turning more and more to the use of multi-role aircraft. Perhaps this could be a model to be emulated by infantry? We can't all be fighters, we can't all be bombers, but perhaps we could be fighter-bombers?

I don't claim to have all the answers, but I do believe that to remain successful in combat we need to be flexible. Which direction the army will go? Only time will tell, but hopefully it will be for the best.