.50 Vickers

The Vickers .5 inch machine gun (officially "Gun, Machine, Vickers, .5-in") also known as the Vickers .50 was a large-calibre British automatic weapon. The gun was commonly used as a close-in anti-aircraft weapon on Royal Navy and Allied ships, typically in a four-gun mounting (UK) or two-gun mounting (Dutch), as well as tanks and other armoured fighting vehicles. It was similar to the .303 in (7.7 mm) Vickers machine gun but fired the enlarged calibre British Vickers 0.5-inch (12.7 mm) ammunition; this round was shorter in length than the American .50 BMG (12.7×99mm).