120-mm L11 tank gun

The British L11 and L30 120-mm/55-caliber tank guns are among the largest rifled combat vehicle guns in current service. The L11, along with its variants, have provided the main armament on the Royal Army's Chieftain and Challenger tanks and on export versions on the Chieftain. The L30 Challenger Armament (CHARM) gun is an extensively modified main gun for the Challenger 2 that was also retrofitted to the Challenger 1 (which is no longer in service).

Both have a one-piece gun...