Editing Challenger 2 (section)

=== Armament ===
[[File:Challenger 2 Tank Firing a Shell MOD 45157421.jpg|thumb|A Challenger 2 firing its main armament during an exercise. The shell is visible to the left of the smoke cloud.]]
[[File:Challenger 2 main battle tank.jpg|thumb|Close-up of muzzle showing rifling]]
[[File:Challenger 2 Tank Firing at BATUS MOD 45157782.jpg|thumb|A row of Challenger 2 on a firing range at [[British Army Training Unit Suffield|BATUS]], Canada]]

The Challenger 2 is equipped with a {{convert|120|mm|in|adj=on}} 55-[[caliber (artillery)|calibre]] long [[Royal Ordnance L30|L30A1]] tank gun,<ref name="janes.com"/> the successor to the L11 gun used on [[Chieftain tank|Chieftain]] and Challenger 1. The gun is made from high strength [[electro-slag remelting]] (ESR) steel with a chromium alloy lining. Like earlier British 120&nbsp;mm guns, it is insulated by a [[thermal sleeve]]. It is fitted with a muzzle reference system and [[fume extractor]], and is controlled by an all-electric control and stabilisation system. The turret has a rotation time of 9 seconds through 360 degrees.

Uniquely among [[NATO]] main battle tank guns, the L30A1 is [[Rifling|rifled]] and along with its predecessor, the [[Royal Ordnance L11A5]], the only Third Generation Main Battle Tank Guns to use a rifled barrel. This is because the British Army continues to place a premium on the use of [[high explosive squash head]] (HESH) rounds in addition to [[armour-piercing fin-stabilized discarding-sabot]] (APFSDS) rounds. HESH rounds have a longer range (up to {{convert|8|km|mi|0|disp=or}} further) than APFSDS, and are more effective against buildings and thin-skinned vehicles.<ref>{{cite book |last1=Kaplan |first1=Philip |title=Rolling Thunder: A Century of tank Warfare |date=2013 |publisher=Pen and Sword |page=161}}</ref>

Forty-nine main armament rounds are carried in the turret and hull. These are a mix of L27A1 APFSDS (also referred to as CHARM 3), L31 HESH and L34 [[white phosphorus]] smoke rounds, depending on the situation. As with earlier versions of the 120&nbsp;mm gun, the propellant charges are loaded separately from the shell or KE projectile. A combustible rigid charge is used for the APFSDS rounds and a combustible hemicylindrical bag charge for the HESH and smoke rounds. An electrically fired vent tube is used to initiate firing of the main armament rounds. The main armament ammunition is described to be "three-part ammunition", consisting of the projectile, charge and vent tube. The separation of ammunition pieces aids in ensuring lower chances of unfired [[cooking off|ammunition detonating prematurely]].

The Challenger 2 is also armed with a [[L94A1 chain gun|L94A1]] EX-34 7.62&nbsp;mm [[chain gun]] coaxially to the left of the main gun, and a 7.62&nbsp;mm [[L7 (machine gun)|L37A2]] (GPMG) machine gun mounted on a pintle on the loader's hatch ring. 4,200 rounds of 7.62&nbsp;mm ammunition are carried. The Challenger can also mount a Leonardo "Enforcer" [[Remote controlled weapon station|remote control weapons system]], bearing a 7.62&nbsp;mm [[L7 (machine gun)|L37A2]] (GPMG) machine gun, a 12.7&nbsp;mm heavy machine gun or a 40&nbsp;mm automatic grenade launcher.<ref>{{cite web |title=Enforcer Remote Control Weapons System Data Sheet |url=http://www.leonardocompany.com/documents/63265270/66465238/mm08109_Enforcer_RWS_LQ_.pdf |website=Leonardo Company |access-date=28 February 2018 |archive-url=https://web.archive.org/web/20180301044344/http://www.leonardocompany.com/documents/63265270/66465238/mm08109_Enforcer_RWS_LQ_.pdf |archive-date=1 March 2018 }}</ref>