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.
i don't know