I found various variations After i appeared. Some were marked M-16A1, and many were marked M16A1. Some experienced SERIAL really stamped on there before the serial quantity, and Some others didn't. AR15.COM is the entire world's major firearm community and is a gathering place for firearm fans of all kinds. https://mariocmtfy.wikiannouncing.com/5658924/indicators_on_gold_cup_trophy_colt_45_you_should_know