A lot of rifles were being rebuilt, especially Vietnam era rifles. Usually the barrels ended up replaced. Some samples of markings found on replacment barrels consist of: Sad to say, I'm on vacation so I can't publish images from the bolt. It really is MPC engraved. The sole marking within https://goldcuptrophycolt4500010.vigilwiki.com/6499183/5_easy_facts_about_colt_combat_elite_commander_45_acp_described