The L30A1, officially designated Gun, 120 mm, Tank L30,is a British-designed 120 mm rifled tank gun, installed in the turrets of Challenger 2 main battle tanks. It is an improved production model of the Royal Ordnance L11 series of rifled tank guns. Challenger 2 tanks and their L30A1 guns are operated by the British and Omani armies. In 2023, L30A1 armed Challenger 2 tanks supplied by the British were delivered to Ukraine.

History

The L30A1 was conceived in the late 1980s as part of the Challenger Armament (CHARM) project for the Challenger 2 tank, then in development by Vickers. Its design developed on the pre-existing Royal Ordnance L11A5 that had armed the Challenger 1 and Chieftain. CHARM was intended to develop a new main armament for the Challenger 2 tank that could also be retro-fitted to the Challenger 1. The project had three components: the gun (prototype known as EXP32M1), developed by the Royal Ordnance Factory, Nottingham, a new depleted uranium (DU) APFSDS round, and a propellant charge for it. CHARM superseded other projects, the EXP 32M1 experimental gun was re-titled the XL30E4 and accepted for production as the L30 in 1989. In the event, the L30 was not used to upgun Challenger 1 tanks, which were withdrawn from British service and sold to Jordan. The first of 386 Challenger 2 tanks were delivered for British service in 1994, with the tank certified for operation in 1998. Deliveries were completed in 2002. Oman ordered 38 Challenger 2 tanks, in two batches in 1994 and 1997, and these were delivered armed with L30 guns. In January 2023, the UK government announced that it was donating L30-armed Challenger 2 tanks to Ukraine, with the first deliveries made at the end of March 2023.

Design

The barrel is 55 calibres long (L55), i.e., 55 times 120 millimetres, or 6.6 m. It is made of electro-slag refined steel. The bore and chamber are electro-plated with chromium to give a barrel life of 500 effective full charges. The gun has a split sliding-block breech mechanism. One vertically sliding block holds a Crossley-type elastomeric 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. Uniquely among modern main battle tank guns, and like the L11 gun that preceded it, the L30 has a rifled barrel. This permits High Explosive Squash Head (HESH) rounds to be fired. HESH ammunition is used both as a general-purpose high explosive projectile, and also against other tanks and armoured vehicles. When HESH ammunition is fired from a rifled barrel, the spin imparted to the projectile helps ensure a predictable distribution of the plasticised explosive filler, and thus maximises its efficiency in the anti-tank role.

Ammunition

The L30 is also unique among modern tank guns in its dependency on two-part ammunition, composed of a projectile, and a propellant charge. These are stored and loaded separately. The ammunition types which are currently or were formerly in use include:

Projectiles

Propellant charges

Operational service

The L30 saw its first offensive use during the Iraq War where Challenger 2s provided fire support for British forces, and destroyed numerous Iraqi tanks. On 25 March 2003, a friendly fire ("blue-on-blue") incident occurred in Basra in which one Challenger 2 of the Black Watch Battlegroup (2nd Royal Tank Regiment) mistakenly engaged another Challenger 2 of the Queen's Royal Lancers after detecting what was believed to be an enemy flanking manoeuvre on thermal equipment. Two High Explosive Squash Head (HESH) rounds were fired, with the second hitting the open commander's hatch lid of the QRL tank sending hot fragments into the turret, killing two crew members. The hit caused a fire that eventually ignited the stowed ammunition, destroying the tank.

Accident

An accident deemed to have been due largely to a design fault in the L30 gun killed two men and injured two others. On 14 June 2017, a Challenger 2 from The Royal Tank Regiment suffered an ammunition explosion during live firing exercises at the Castlemartin Range in Pembrokeshire. The tank was firing 120 mm practice shells with a standard propellant charge. The explosion critically injured the four-man crew, with two later dying of their wounds in hospital. All British Army tank firing exercises were suspended for 48 hours while the cause of the explosion was investigated. It was determined that a bolt vent axial (BVA) seal assembly had been removed during an earlier exercise and had not been replaced at the time of the incident, allowing explosive gases to enter the turret space, detonating two bag charges that had not been stowed in the internal ammunition bins as required by correct procedure. The lack of a written process for removal and replacement of the seal assembly meant that the crew were unaware of its absence. The coroner at the inquest said that the main cause of the incident was that inadequate consideration had been given during the production of the L30 gun as to whether it could be fired without the seal assembly.

Operators

Weapons of comparable role, performance and era