The Vickers .50 machine gun, also known as the 'Vickers .50' was basically similar to the .303 inches (7.70 mm) Vickers machine gun but scaled up to use a larger calibre 0.5-inch (12.7 mm) round. It saw some use in tanks and other fighting vehicles, but was much more commonly used as close in anti aircraft weapons on Royal Navy and allied ships, typically in a 4 gun mounting. The Vickers fired UK 12.7×81mm 50-calibre ammunition, not the better known US 12.7×99mm.