George Hyde designed the gun that would eventually be adopted as the M2 submachine gun in the late 1930s, and it was first tested at Aberdeen Proving Grounds in October of 1939. At that time, the gun had many good traits (weight, handlings, etc) but suffered from parts breakage and unreliability. Hyde went back to work on the gun at the Inland Division of GM, and came back with a much improved version in April of 1942.

The Inland-Hyde SMG was chambered for .45 ACP ammunition and used standard Thompson magazines, and was poised to become the US Army's new submachine gun, replacing the overly expensive Thompson. The Hyde passed a 6080 round endurance test with flying colors, and exhibited much better effectiveness in fully automatic than the Thompson. At the end of the April tests, it was formally accepted to replace the Thompson and given the designation M2.

A contract was given to the Marlin company (Inland being busy with other projects) to manufacture 164,450 of the guns, with delivery to begin in December 1942. However, Marlin had problems tooling up to produce the new gun, in particular with dies for several parts to be made using powdered metal sintering. Actual delivery of the first guns did not happen until May of 1943. In the meantime, Hyde and Inland had continued working on cheaper and simpler designs, and created the stamped sheet metal M3 "Grease Gun". By the time the M2 was actually ready for delivery, the M3 had been tested and accepted by the Army as a better replacement than the M2. By mid-June, the M2 was declared obsolete and Marlin's contract cancelled.

In total only about 500 M2 submachine guns were made, with (I believe) 6 surviving today. The example in this video is a semiautomatic-only reproduction made from scratch by a viewer of the channel, who graciously offered to loan it to me for this filming. Thanks, K!