Royal Ordnance L7A1

Royal Ordnance L7
M68 105mm gun, the American version of the L7, mounted on an M1 Abrams
Type	Rifled Tank gun
Place of origin	United Kingdom
Production history
Manufacturer	Royal Ordnance Factory
Specifications
Weight	1,282 kg (2,826 lb)
Length	5.89 m (19.3 ft)
Barrel length	52 calibres
Calibre	105 mm (4.13 in)
Rate of fire	10 rounds per minute (maximum)

The Royal Ordnance L7 is the basic model of Britain's most successful tank gun. The L7 was a 105 mm L/52 rifled design by the Royal Ordnance Factories intended for use in armoured fighting vehicles, replacing the earlier 20-pounder (84 mm) tank gun mounted on the Centurion tank. The successful L7 gun was fitted on many armored vehicles that include the British Centurion (starting from the Mk. 5/2 variant), the German Leopard 1 and the US M1 Abrams (M1 and M1IP).

The L7 was a popular weapon and continued in use even after it was superseded by the L11 series 120 mm rifled tank gun, for some Centurion tanks operating as Artillery Forward Observation and Armoured Vehicle, Royal Engineers (AVRE) vehicles. The L7, and adaptations of it, can be found today as standard or retrofitted equipment on a wide variety of tanks developed during the Cold War.

Work on what became the L7 began in the early 1950s under Armament Research and Development Establishment at Fort Halstead with the first gun trials in mid-1956. Later that year during the Hungarian Revolution of 1956, a Soviet T-54A medium tank was driven onto the grounds of the British embassy in Budapest by the Hungarians. After a brief examination of this tank's armour and 100 mm gun, British officials decided that the 20 pounder was apparently incapable of defeating it. Hence there was a need to adopt a 105 mm gun.

The L7 was specifically designed to fit into the turret mountings of the 20 pounder. This would enable the Centurions to be upgunned with minimum modifications; hence, the fleet could be upgraded in a shorter time and at a lower cost.