The Mag launch button experienced a horizontal line sample on it, as opposed to the round line sample observed on The existing kinds, see the picture under for an illustration: The "C" on the barrel would reveal a chrome chamber only barrel. But AFAIK, Colt marked the "C" up close https://reidbbzxt.tdlwiki.com/1060385/the_basic_principles_of_gold_cup_trophy_colt_45