What cartridge was developed in 1910 and is currently used in the M2 machine gun?
.50 BMG The .50 Browning Machine Gun (.50 BMG, 12.7×99mm NATO and designated as the 50 Browning by the C.I.P.) is a cartridge developed for the Browning .50 caliber machine gun in the late 1910s. Entering service officially in 1921, the round is based on a greatly scaled-up .30-06 cartridge. Under STANAG 4383, it is a standard cartridge for NATO forces as well as many non-NATO countries. The cartridge itself has been made in many variants: multiple generations of regular ball, tracer, armor-piercing (AP), incendiary, and saboted sub-caliber rounds. The rounds intended for machine guns are linked using metallic links.
7.65×21mm Parabellum The 7.65×21mm Parabellum (designated as the 7,65 Parabellum by the C.I.P. and also known as .30 Luger and 7.65mm Luger) is a pistol cartridge that was introduced in 1898 by German arms manufacturer Deutsche Waffen und Munitionsfabriken (DWM) for their new Pistol Parabellum. The primary designers were firearms designers Georg Luger and Hugo Borchardt, who developed the round from the earlier 7.65×25mm Borchardt while working at DWM.