Campaigning for a ban on Depleted Uranium weapons
A short history of the UK development of DU anti-tank ammunition
The Challenger I tank first came into service with the armed forces in March 1983. Ammunition available for it in its original incarnation included two armour piercing round – the L15 APDS round, and the more advanced L23 APFSDS, both of them tungsten based.
An upgrade made in 1991, prior to the Gulf War included explosive resistant armour and a new projectile & charge system (unusually, the UK’s tank ammunition comprises a separate charge and projectiles rather than a combined cartridge). The name for the ammunition part of the programme was CHARM 1 (CHallenger ARmament), and it was originally intended to replace both the gun and the ammunition. In the event, a decision was taken to upgrade the projectile and charge only, and to bring forward a more fundamental upgrade of the tank. So, the Challenger I went into the Gulf War with the 120mm rifled L11A5 gun and the L26 APFSDS DU round. In time the name CHARM 1 became synonymous with the round, rather than the programme that produced it.
The more fundamental upgrade to the tank was the Challenger II, with design beginning in September 1990, and the first orders being placed in June 1991. It was equipped with an upgraded 120mm rifled L30A1. The Challenger I was finally phased out of service in late 2000, meaning that the UK’s main battle tanks are all now Challenger IIs.
The upgraded DU round, the L27A1 began being designed in the early 1990s, and is known as CHARM 3 (it appears that CHARM 2 applies to a tungsten round, possibly the L28 APFSDS, or to a programme which did not get off the ground). Development of the round was delayed from 1997 onwards due to a lack of suitable firing ranges, and it eventually became available in 1999. It has a greater penetrator length to diameter ratio than the L26, so is more effective at penetrating armour. The DU comes from US stocks, rather than British, and this was probably the case for the earlier L26 round as well. Looking at the development timeline, it seems likely that the L27A1 also has design features that were originally intended for CHARM 1, but were changed to ensure compatibility with the L11A5 gun on the Challenger I.