High Quality Content by WIKIPEDIA articles! The StG 45(M) (Sturmgewehr 45 literally "storm rifle" or "assault rifle 1945") sometimes referred to as the MP 45(M), was a prototype assault rifle developed by Mauser for the Wehrmacht at the end of World War II, using an innovative roller-delayed blowback operating system. It fired the 8x33mm Kurz (or "Pistolenpatrone 7.9mm) intermediate cartridge at a cyclic rate of around 450 rounds per minute.