[devbug]

Logistics is your force multiplier. Sacrificing the (excessive) performance of 7.62 to improve the rounds you can field is well worth it. That said, 5.56 still holds up well in CQB, provided you have a sufficiently long barrel and a bullet with decent ballistics. But therein lies the problem. The move to shorter barrels means lower muzzle velocity which severely gimps a round that leans on velocity for its lethality. The move to shorter barrels has also necessitated the move to piston-operated guns like the HK416, but they don't come without negatives, especially when guys are over-gassing out of fear of stoppages.