The armament of the "Defence"-class ships was intended to be 18 smoothbore, muzzle-loading 68-pounder guns, eight on each side on the main deck and one each fore and aft as chase guns on the upper deck, plus four Armstrong 40-pounder guns, an early rifled breech loader (RBL) design, as . The 68-pounder weighed and had a range of with solid shot. During construction the armament was changed to include six ("Defence") or eight ("Resistance") rifled 110-pounder guns, ten 68-pounders and either two 32-pounder smoothbores ("Resistance") or four breech-loading guns ("Defence"). The innovative 110-pounder, whose shell could reach was in short supply when the ironclads were launched, but poor results in armour-penetration tests halted plans to fully equip the ironclads with this gun. The 110-pounders blew up when other ships used them in action, were labour-intensive to load and fire, and were henceforth only used with a reduced propellant charge, which left them useless in practice.