What cartridge, also known as 9 mm Luger by the C.I.P. or 9 mm NATO by NATO, is used in the submachine gun the MP 40?
9×19mm Parabellum The 9×19mm Parabellum, also known as 9 mm Luger by the C.I.P. or 9 mm NATO by NATO (abbreviated 9mm, 9mmP, 9×19mm or 9×19) is a cartridge that was designed by Georg Luger and introduced in 1902 by the German weapons manufacturer Deutsche Waffen und Munitionsfabriken (DWM) (German Weapons and Munitions Factory) for their Luger semi-automatic pistol.
Interdynamic MP-9 The Interdynamic MP-9 is a blowback-operated, fully automatic 9 mm caliber firearm, classified by BATF as a submachine gun. It is made of inexpensive molded polymer and stamped steel parts. 10-, 20-, 32-, 36- and 50-round magazines are available.