The sub-machine guns being used by most of the Dirty Dozen are M3, .45 ACP Cal., sub-machine guns know as the "Grease Gun". It came into use late in the war replacing Thompson sub-machine guns. It was not a general issue weapon to infantryman, normally it was the crew weapon on a tank. Many "found" their way to the frontline troops. This earlier model weapon had a charging lever on the side. Later models (M3A1) were charged by simply pulling back on the bolt by inserting your finger into a recess in the bolt. The M3A1 wire stock included a tab to help load magazines, the ends threaded to accept a cleaning brush to clean the barrel and was used as a wrench to unscrew the barrel for disassembly. The weapon, only manufactured during WWII by General Motors Headlight division, at a cost about $20 vs. the Thompsons at a few $100 each.
This was the first commercially produced Hollywood film to open the Edinburgh International Film Festival in 1967 (the festival began in 1947 under the name of the First International Festival of Documentary Films).