[Still Thinking]

Weren't there reports from Afghanistan that the M4 platform was not powerful enough. The ballistics are different between a Remington .223 and a SS109 and shame on McCrystal for disseminating false information.

That's what I heard as well. They were doing a significant amount of fighting at ranges there the 7.62x51 did a much better job (and even larger sniper rounds of course, but that's another whole kettle of fish).

[Perdogg]

Actually they evaluated the 6.8mm SPC and 6.5mm Grendel.