Colt m4a1 upper receiver - Colt 223 Rem/ 556 NATO M4 Feed Ramps Upper

The one I received has the Colt cage code engraved on the upper right side with the square forge marking. It also has the M4 feed ramps. It came with a black dust cover spring, which I don't care for,so I replaced it with a chrome spring. It has the white markings between the grooves of the 1913 rail also. The finish was excellent, with no blemishes or scratches. The dust cover fits tight at the top when closed,but it has a little play at the hinge area where the rod goes through ths cover. But that seems to be a hit or miss issue with all brands these days. The forward assist operates smoothly with no gritty feel to it. The feed ramps match up well with the Luth SOCOM barrel I've mounted to this upper. The barrel nut fit well and the threads were perfect. I'm very pleased with this receiver.