The mag launch button experienced a horizontal line pattern on it, vs . the round line sample observed on the current types, see the picture under for an illustration: It's the early reciever without fence throughout the mag release and all early kind release pins with holes in the center. https://zionkdvip.wikicorrespondence.com/4119813/indicators_on_gold_cup_trophy_colt_45_you_should_know