I just recently purchased a "M3" grease gun. It has been converted to semi-auto for NFA reasons but is the real thing. I find the quality of manufacture very good and inline with most other "stamped" weapons. Very simply built, rugged, and simple maintenance which are the trademarks of this SMG. Also it is a blast to shoot and even my petite wife can handle it. I think there would be no firepower differences between the Thompson and the M3, therefore no real reason to include the M3 in CM. Plus the Thompson is infamous when compared to the M3.