 BL 10-inch Mk I – IV naval gun

The BL 10 inch guns Mks I, II, III, IV were British rifled breechloading 32-calibre naval and coast defence guns in service from 1885.The British 10-inch calibre originated with the Committee on Ordnance in 1879 when it ordered a new 10.4-inch gun together with the new 9.2-inch  as part of its transition from muzzle-loading to breech-loading guns.