Royal Ordnance L7

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The Royal Ordnance L7 is the basic model of Britain's most successful tank gun. The L7 was a 105 mm rifled design intended for use in armored fighting vehicles. It was so successful that it armed not only British post-war designs, but was used almost universally in "the West" as the main armament of almost every main battle tank.

The L7 was developed by Britain's Royal Ordnance Factories to equip British tanks of the postwar (Cold War) period as the successor to the 20 pounder used on Britain's postwar tank—the Centurion.

The L7 was a popular weapon and it was maintained in use even after it was superseded by the L11 series 120 mm rifled tank gun for some Centurion tanks operating as Artillery Forward Observation and Armoured Vehicle, Royal Engineers (AVRE)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. It is also being used as the main armament of the U.S. Army's Stryker-based Mobile Gun System.

Contents 1 History 2 Technology 3 Specification 3.1 Ammunition Available 4 Variants 5 Use 6 Notes 7 References

[edit] History

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 an 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.^[1]

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.

The first tank to be equipped with the L7 was the Centurion Mark 5 in 1959.^{[citation needed]} The gun was subsequently adopted by several other nations for their own MBTs, most notably the German Leopard 1 (for which the L7A3 variant was developed), the Japanese Type 74 (produced under license by Japan Steel Works), the Swedish Stridsvagn 103 (as the L74, with a longer barrel and automatic loader), the US M60 series of tanks (with the M68), and the Israeli Merkava. In addition, several countries have used the gun to improve the firepower of existing main battle tanks. Derivatives have even been mounted in Warsaw Pact-built T-54 and T-55 tanks in Israel, Egypt and Iraq, and Type 79 tanks in China.

[edit] Technology

The breech uses a horizontally-sliding breechblock for loading the fixed cartridge cases. The gun recoils approximately 29 cm (in most applications), automatically ejecting the empty cartridge case upon reaching full recoil. The barrel of the L7 is fitted with a bore evacuator approximately halfway down its length. It is eccentrically mounted, which is a key recognition feature.

[edit] Specification

• Caliber: 105 mm
• Weight: 1,282 kg
• Length: 5.89 m
• Rate of fire: 10 rounds per minute (maximum)

[edit] Ammunition Available

• APDS
• APERS-T ("Anti-personnel-tracer")
• APFSDS
• Dummy
• HE
• HEAT
• HESH
• Smoke-White phosphorus incendiary
• Target Practice
• Target Practice Discarding Sabot

[edit] Variants

• L7A1

Standard British production variant.

• L7A3

Variant for the (West) German Leopard 1 MBT. The upper rear corner of the breech block reduced in size so gun can be depressed without hitting the turret roof.

• L74

Swedish variant with a 62 calibre (6.51 m) barrel used only for the Stridsvagn 103 MBT.

• M68

US built variant for M60 Patton. Utilises a round breech with a vertically-sliding breechblock, and a different design of bore evacuator.

• KM68A1

Republic of Korea Army's license-produced variant of the U.S. M68 gun. Used on M48A3K, M48A5K and K1 tanks.

• Type 79/81/83

Chinese copies of an L7 supplied by Austria.

[edit] Use

• Centurion

and derivatives such as Olifant

• EE-T1 Osório
• Leopard 1
• M1 Abrams
• M47 Patton in some upgraded variants (for example Spanish M47E1 and M47E2)
• M48 Patton in some upgraded variants (M48A5, Israeli-rebuilt M48s, etc.)
• K1 Type 88
• M60 Patton
• Merkava I and II
• OF-40
• Pz-61 & Pz-68
• Stridsvagn 103
• Stryker MGS
• T-54 in several upgraded variants (for example Israeli Tiran-4Sh)
• T-55 in several upgraded variants (for example Egyptian modified T-55s)
• TAM medium tank
• Type 74
• Vijayanta
• Ramses II

[edit] Notes

1. ^ Zaloga 2004, pp 13, 39.

[edit] References

• Zaloga, Steven J. and Hugh Johnson (2004). T-54 and T-55 Main Battle Tanks 1944–2004. Oxford: Osprey. ISBN 1-84176-792-1.