ive got a upper i bought back in the early 90's from olympic arms in 45 acp. in shot it maybe 200-300 times. i havent used it in almost 15 years the magazine disappeared in one of the 4 times ive moved since i shot it. its a A1 shorty style 16inch CAR type barrel. operation is direct blowback. not sure what i wanna do with it. or what its worth.