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.
7×64mm The 7×64mm (also unofficially known as the 7×64mm Brenneke, though its designer's name officially never was added as a part of this cartridge name) is a rimless bottlenecked centerfire cartridge developed for hunting. As is customary in European cartridges the 7 denotes the 7 mm bullet caliber and the 64 denotes the 64 mm case length. The 7×64mm is a popular hunting cartridge in Central Europe and can, due to its 11.95 mm case head diameter and 84 mm overall length, easily be chambered in Mauser 98 bolt action rifles that were then standard issue in the German military.