Several Rifles were rebuilt, Particularly Vietnam period rifles. Generally the barrels have been changed. Some examples of markings observed on replacment barrels include things like: Of course, I am absolutely sure the higher receiver is Colt, together with the BCG. It is absolutely the barrel that's questionable to me. even https://coltcombatunitrailgun4555550.bloggactivo.com/30673027/not-known-facts-about-colt-combat-unit-rail-gun-45