The origin of this rifle can be traced back to the final years of World War II when Mauser engineers at the Light Weapon Development Group ("Abteilung 37") at Oberndorf am Neckar designed the MKb "Gerät" 06 ("Maschinenkarabiner Gerät 06" or "machine carbine instrument 06") prototype assault rifle chambered for the intermediate 7.92×33mm Kurz cartridge, first with the "Gerät" 06 model using a roller-locked mechanism which was unique for being gas operated, as opposed to recoil operation, originally adapted from the MG 42 machine gun, but with a fixed barrel and conventional gas-actuated piston rod. After observing bolt-bounce during firing trails of the roller locked Gerät 03 prototype semi-automatic rifle Dr. Karl Maier, one of Mauser's scientists at the time, realized that with careful attention to the mechanical ratios, the gas system could be omitted. The resultant weapon, the "Gerät" 06H (the "H" suffix is an abbreviation for "halbverriegelt" or "half-locked") was assigned the designation StG 45(M) ("Sturmgewehr 45(M)").