PPSh-41
After the German Army captured a lot of PPSh-41s during World War II, a program was started. In this program, the weapons would be altered to fire the German submachine gun bullet, the 9mm Parabellum. The Wehrmacht officially called these PPSh-41s the MP41(r). PPSh-41s which were not altered were called the MP717(r). They were given 7.63x25mm Mauser ammunition instead of the Soviet 7.62x25mm bullet.  The German military made German-language manuals to teach soldiers how to use the PPSh-41. These were printed and given out across the Wehrmacht.