The following article tells the story.
22 February 2006 JDW
Christopher F Foss
Jane's Land Forces Contributing Editor, London
Challenger 2 tested with 120 mm smoothbore gun
A British Army Challenger 2 main battle tank (MBT) armed with a hybrid German Rheinmetall 120 mm L/55 smoothbore gun has recently undergone a series of successful firing trials in the UK.
The British Army has a total of 386 BAE Systems Land Systems Challenger 2 MBTs all armed with a 120 mm L30 rifled tank gun. The UK is the only major NATO member to use a 120 mm rifled tank gun as most countries now opt for a 120 mm smoothbore weapon.
The 120 mm L30 rifled tank gun fires a depleted uranium (DU) type armour-piercing fin-stabilised discarding sabot (APFSDS) projectile that is only used in combat.
There has been no recent UK production of the 120 mm DU round, which is now out of favour with most countries, or of other 120 mm ammunition types such as smoke or high-explosive squash head (HESH).
Following a competition, the then RO Defence was awarded a GBP3.5 million plus (USD6 million) contract from the Defence Procurement Agency (DPA) for the 120 mm Smoothbore Option Technical Demonstrator Programme (SO TDP).
The programme essentially uses the German Rhein-metal! 120 mm U55 smoothbore tank gun, which is fitted into the latest German Krauss-Maffei Wegmann Leopard 2A6 MOT. So far two hybrid 120 mm U55 barrels have been supplied to the UK plus a quantity of ammunition.
Ballistically the new weapon is the same as the German 120 mm L/55 but externally can tit into the space previously occupied by the L30.
The current Challenger 2 installation retains the L30 rifled gun's cradle, gun clamp, thermal sleeve, fume extractor and muzzle reference system.
Following trials in Germany the weapon was also tested in a static mount installed on a Centurion chassis in mid-2005 and late last year was finally integrated into a Challenger 2 MBT.
Static firing trials have been conducted against a wide range of targets firing the Rheinmetall 120 mm DM53 APFSDS projectile with a conventional penetrator. These trials are understood to have shown that the DM53 gives enhanced performance over the current 120 mm CHallenger ARMament (CHARM) 3 DU round.
