Eugene Reising developed a .45 ACP submachine gun in the late 1930s that was basically the opposite of the Thompson - it was light and handy, fired from a closed bolt with a delayed blowback action, and was inexpensive to produce. Reising contracted with Harrington & Richardson to produce the gun, and when it entered the market in early 1940 it found immediate interest form the USMC. Looking initially to equip the Marine Paratroop Regiment (Paramarines), the Corps wanted a gun that was light and compact. The Reising M55 with it folding stock was certainly those things and since the Thompson was essentially unavailable anyway (all production was going to the Army and foreign contracts), the Corp adopted the Reising with initial purchases of both the M50 and M55 in January and February of 1942.

What we are looking at today is an early production M50. It is blued with 29 barrel fins and the early style of sights, stock screw, trigger guard, magazine release, stock (the lacquer coating and sling swivels having been added by a previous owner), and firing pin. Later production guns would be improved and strengthened in various ways, but the Reising would never quite meet the needs of frontline combat troops, much to the displeasure of the Marines who first used them in the Pacific theater. Lacking interchangeable parts and susceptible to fouling and malfunctions, the Reisings were quickly replaced by other arms - some Johnson M1941 rifles, some M1 and M1A1 carbines, and various other guns. Rotated back to duties like ship boarding parties, guards, and military police, the Reising served very well. They were indeed handy and accurate guns, just not built for the extreme rigors of Pacific beach assaults and jungle foxholes.