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.
.303 Magnum The .303 Magnum is a bottleneck centerfire rifle cartridge developed by W.J. Jeffery & Co and introduced in 1919. It was produced in both semi-rimmed and rimless versions.