The L30 is a 120mm tank gun

Tank gun

A tank gun is the main armament of a tank. Modern tank guns are large-caliber high-velocity guns, capable of firing kinetic energy penetrators, high explosive anti-tank rounds, and in some cases guided missiles. Anti-aircraft guns can also be mounted to tanks.-Overview:Tank guns are a specific...

 used by the British Army

British Army

The British Army is the land warfare branch of Her Majesty's Armed Forces in the United Kingdom. It came into being with the unification of the Kingdom of England and Scotland into the Kingdom of Great Britain in 1707. The new British Army incorporated Regiments that had already existed in England...

 and Royal Army of Oman

Royal Army of Oman

The Royal Army of Oman protects the sovereignty of Oman. In terms of matériel, the Army is small but well equipped to the extent that external aggression is now realistically deterred.-Field organization:*One divisional HQ...

. It is fitted in the turret of the Challenger 2 main battle tank

Main battle tank

A main battle tank , also known as a battle tank or universal tank, is a tank that fills the heavy direct fire role of many modern armies. They were originally conceived to replace the light, medium, heavy and super-heavy tanks. Development was spurred onwards in the Cold War with the development...

. It is an improved production model of the Royal Ordnance

Royal Ordnance

Royal Ordnance plc was formed on 2 January 1985 as a public corporation, owning the majority of what until then were the remaining United Kingdom government-owned Royal Ordnance Factories which manufactured explosives, ammunition, small arms including the Lee-Enfield rifle, guns and military...

 L11

Royal Ordnance L11A5

The Royal Ordnance L11A5 is a 120 mm L/55 rifled tank gun design. It was the first of NATO's 120mm tank guns which became the standard calibre for Western tanks in the later period of the Cold War...

 series of rifled

Rifling

Rifling is the process of making helical grooves in the barrel of a gun or firearm, which imparts a spin to a projectile around its long axis...

 tank guns.

Challenger Armament

The Challenger Armament or CHARM project was intended to provide a new main armament for the Challenger II tank and to be fitted retrospectively to the Challenger 1. It involved three components: the gun, developed by the Royal Ordnance Factory, Nottingham

ROF Nottingham

Royal Ordnance Factory Nottingham, first opened in 1916 and first opened as an ROF January 1936 was one of a number of Royal Ordnance Factories created at the start of World War II.-Background:R.O.F...

, the Depleted Uranium

Depleted uranium

Depleted uranium is uranium with a lower content of the fissile isotope U-235 than natural uranium . Uses of DU take advantage of its very high density of 19.1 g/cm3...

 (DU) APFSDS round and a propellant charge for it.

After earlier projects were cancelled, the EXP 32M1 experimental gun was retitled the XL30E3 and accepted for production as the L30 in 1989.

Design

The barrel is 55 calibres long (L55) and is made of electro-slag refined (ESR) steel. The bore and chamber are electro-plated with chromium to give a barrel life of 400 effective full charges.

The breech mechanism is a split sliding-block breech. One vertically sliding block holds the obturation ring (which is necessary because the propellant charges are combustible cases or bags) and is locked for firing by a second block. When the second block falls, the first is released to open the breech.

Ammunition

The ammunition types which are currently or formerly in use include:

• APFSDS L23. This has a monobloc tungsten nickel copper long rod penetrator, and used the L8 combustible case charge, although it can use a modified L14 charge. The muzzle velocity is 1534 metres per second (5,032.8 ft/s). It was used in the Gulf War
  Gulf War
  The Persian Gulf War , commonly referred to as simply the Gulf War, was a war waged by a U.N.-authorized coalition force from 34 nations led by the United States, against Iraq in response to Iraq's invasion and annexation of Kuwait.The war is also known under other names, such as the First Gulf...
  
  , but is now probably withdrawn.
• APFSDS L26 (alias CHARM 1). This has a depleted uranium
  Depleted uranium
  Depleted uranium is uranium with a lower content of the fissile isotope U-235 than natural uranium . Uses of DU take advantage of its very high density of 19.1 g/cm3...
  
   (DU) long rod penetrator and uses the L14A1 or L14A2 combustible case charges.
• APFSDS L27A1 (alias CHARM 3). This also has a DU projectile, but with a greater length-to-diameter ratio and is thus "significantly more effective". The round uses the L16A1 combustible case charge.
• CHARM 3 training round (C3TR). Because DU rounds are normally fired in wartime only, a tungsten-based projectile is used for training purposes. Opposition to the use of Depleted Uranium even in wartime has led to the further development of the training round as the L28 round.
• DS/T Prac L20A1 This is a relatively low-cost training projectile with the subprojectile penetrator made from steel with a light alloy nose. It is lighter, but matches the L23 trajectory to 2000 metres (6,561.7 ft). Its use also extends barrel life.
• HESH L31 This is employed as a general purpose high explosive round, though it also has a good anti-armour performance, and is effective against fortifications and structures. The HESH L31 is fired using the L3 bag charge. Muzzle velocity is 670 metres per second (2,198.2 ft/s).
• SH/Prac L32A6 A training projectile, which matches the trajectory of the HESH L31. It is available as a completely inert form, or can be filled with an inert HE substitute (a composition of calcium sulphate and castor oil) or an inert HE substitute plus a live fuze and a flash pellet for spotting purposes.
• WP Smoke L34 Matches the HESH L31 in ballistic performance. It is the same shape, though is supplied in a different colour to prevent confusion.