GOLD CUP TROPHY COLT 45 - AN OVERVIEW

I found various versions when I appeared. Some ended up marked M-16A1, and many had been marked M16A1. Some experienced SERIAL essentially stamped on there prior to the serial amount, and Some others did not.Sure, I'm confident the higher receiver is Colt, combined with the BCG.  It is actually the barrel that is certainly questionable to me.Nonet