High Quality Content by WIKIPEDIA articles! The Ordnance QF 75 mm, abbreviated to OQF 75 mm, was a British tank-gun of the Second World War. It was used instead of the Ordnance QF 6 pounder ("6 pdr"), an anti-tank gun, to give better performance against infantry targets in a similar fashion to the 75 mm gun fitted to the American Sherman tank. The QF came from "quick-firing". The gun was also sometimes known as ROQF from Royal Ordnance (the manufacturer) Quick-Firing.