| Ordnance BL 10 inch gun Mk I - IV | |
| Origin: | United Kingdom |
| Type: | Naval gun Coast defence gun |
| Is Ranged: | YES |
| Is Artillery: | YES |
| Is Uk: | YES |
| Service: | 1885 - 1913 |
| Used By: | Royal Navy |
| Variants: | Mk I, II, III, IV |
| Weight: | Mk I : 32 tons barrel & breech Mks II - IV : 29 tons[1] |
| Part Length: | Mk I : 317.5inches (31.75 calibres) Mks II - IV : 320inches (32 calibres) |
| Cartridge: | 500lb |
| Caliber: | 10sing=onNaNsing=on |
| Velocity: | 2040ft/s[2] |
| Max Range: | 10000yd |
The BL 10 inch guns Mks I, II, III, IV[3] 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 [4] as part of its transition from muzzle-loading to breech-loading guns. The proposed 10.4-inch gun eventually went into service in 1885 as a 10-inch gun firing a 500-pound projectile.
After Mk IV of 1889 the Royal Navy discontinued the 10-inch calibre in favour of 9.2-inch and 12-inch.
Mks II, III and IV guns were interchangeable and equipped the following warships :
A 25-ton version with a barrel of 300 inches (30 calibres) and firing a 450-pound projectile was supplied in 1884 to the Australian colony of Victoria, mounted on the gunboat HMVS Victoria.[5] This gun was subsequently replaced on Victoria by an 8-inch gun, and in 1887 was mounted at Fort Franklin as a coast defence gun.[6]
Mk I was an Elswick Ordnance design used only for coastal defence. Mks II, III and IV were interchangeable Woolwich Arsenal designs used on warships but also for coastal defense around the British Empire, some on disappearing carriages.[7]