FACTS ABOUT COLT SMG UPPER RECEIVER REVEALED

The top in the bolt carrier groups. The top is the typical 5.56mm bolt provider team. See the bolt, cam pin plus the provider essential. On The underside could be the 9mm SMG bolt group.It's a typical FSB and no I had no troubles sighting it in. I at first constructed it having a DPMS A2 upper receiver just before obtaining the 604 receiver. I'd no