The StG-45(M) was developed by engineers at Mauser right at the end of WWII, and its designers went on to form Heckler & Koch and this rifle was their basis for the H&K roller-delayed blowback series of weapons (HK91, HK33, HK53, HK21, MP5, etc). Twenty sets of parts for the StG-45(M) were produced at Mauser, although the war ended before any were made into complete guns (a few were finished by Allied intelligence units after the war for testing). The rifle is chambered for 8x33 Kurz, and handles extremely well.