I just bought a used Colt M16A1 upper with a M16 bolt carrier assembly in it. The full auto bolt carrier isn't going to work for me, because I have a lower with a sear block. The bolt is marked with the MPC, and the carrier has no markings that I can see . The person who sold me the upper stated that the carrier was USGI issue for the M16A1, and that he couldn't say for sure if the carrier was accually Colt or not, because Colt carriers weren't marked in the 1960's. I'm really just looking to trade for a semi carrier ( perfur Colt or bushmaster ). If I have too, I'll sell the complete carrier for $125.00 shipped. No IM's ( please ). I'll also give a inspection of the carrier if wanted. Trade pending.