This is a very nice example of a late WWII US Army contract M3A1 SMG manufactured by the Guide Lamp Division of GM. These were developed in the 1941-1942 time frame as a wartime substitute for the Model 1928 Thompson SMG which although was a superb SMG proved to be costly to produce. This is a late production model that was manufactured originally as a "M3A1" SMG. The left side of the magazine well is marked "SUB-MACH. GUN/ CAL. 45 M3A1/Guide/Crossed Cannons (Ordnance proof)/U.S. NO 623442". As noted this late production model has the combination ejection port cover/safety on the right side. It has a fixed front and rear sight and is fitted with a retractable wire stock complete with an original oiler stored inside the rear pistol grip. There is a very small import mark of "INTER AMERICAN SAC.CA." on the left side behind the front sling loop. It does not come with any magazine.