Really? Did they not waste enough time, money and effort on the FN SCAR?
First of all, the M-14's are being used in the SDM role not general issue to all squad members. The reason for it wasn't for the range(which in Astan is a plus) but for the superior penetration of walls, cars, etc than the M855 in the M4. I've yet to meet an Infantry squad that wants all 7.62NATO to carry as the EBR chassis adds some weight to the original M14, and the ammo load is heavy for comparable number of rounds.
SOCOM's issue with the M4A1(which has Full Auto as opposed to 3 rd Burst of the M4) is they use it like a Belt fed LMG when in contact. Something it was not designed for. If you run around burning through 2-300 rds in 2-3 minutes you're going to wind up with problems of the Bolt Carrier expanding and the gas port eroding in an elongated oval with plays hell with the pressure it was designed for.
What SOCOM wants in a rifle isn't neccessarily what the rest of the Army needs