The sensor is based on UK TICM 2 common modules. The Thermal Observation and Gunnery Sight II (TOGS II), from Pilkington Optronics, provides night vision. The commander's station is equipped with eight periscopes which provide 360 degree vision. A laser rangefinder is incorporated into an intermediate assembly. The commander has a panoramic VS 580-10 gyrostabilised sight from SFIM Industries. The digital fire control computer from Computing Devices Company has capacity for additional systems, for example a Battlefield Information Control System. The loader has a 7.62 mm GPMG 元7A2 anti-air machine gun, mounted on the cupola. Challenger 2 is also equipped with a Boeing 7.62 mm chain gun, which is located to the left of the main tank gun.

The gun control is provided by an all-electric gun control and stabilisation system from BAE SYSTEMS.

A Charm 3 system is under development in which the DU projectile has a higher length to diameter aspect ratio for increased penetration. With the DU round, the 元0 is part of the Charm 1 gun, charge and projectile system. The 元0 gun can also fire the Depleted Uranium (DU) round with a stick charge propellant. There is capacity for 50 120 mm projectiles, including armour piercing fin-stabilised discarding sabot (APFSDS), high explosive squash head (HESH) or smoke rounds. The turret is capable of 360 degree rotation and the weapon elevation range is from -10 to +20 degrees. It is fitted with a muzzle reference system and fume extraction. The gun is made from electro-slag refined steel (ESR) and is insulated with a thermal sleeve. Challenger 2 is equipped with an 元0, 120 mm rifled tank gun from the Royal Ordnance division of BAE SYSTEMS.

Challenger 2 main battle tank