BL 10 inch gun Mk I – IV
|Ordnance BL 10 inch gun Mk I - IV|
Mk I coast defence gun, Hong Kong Museum of Coastal Defence
Coast defence gun
|Place of origin||United Kingdom|
|In service||1885 - 19??|
|Used by||Royal Navy|
|Variants||Mk I, II, III, IV|
|Weight||Mk I : 32 tons barrel & breech
Mks II - IV : 29 tons
|Barrel length||Mk I : 317.5 inches (8,064 mm) (31.75 calibres)
Mks II - IV : 320 inches (8,128 mm) (32 calibres)
|Shell||500 pounds (226.8 kg)|
|Calibre||10-inch (254.0 mm)|
|Muzzle velocity||2,040 feet per second (622 m/s)|
|Maximum firing range||10,000 yards (9,100 m)|
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. 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 :
- Victoria-class battleships laid down 1885
- Centurion-class battleships laid down 1890
- Renown laid down in 1893
- Devastation-class battleships as re-gunned in 1890
25-ton gun for Victoria
A 25-ton version with a bore 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. 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.
Coast defence gun
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.
- Hong Kong Museum of Coastal Defence
- Portsea, Victoria, Australia
- York Redoubt, Purcells Cove, Nova Scotia, Canada
Notes and references
- Text Book of Gunnery 1902, Table XII Page 336
- 500 lb projectile, with 252 lb brown prism powder (gunpowder) or 76 lb cordite propellant size 30. Text Book of Gunnery 1902
- Mks I, II, III, IV = Marks 1, 2, 3, 4. Britain used Roman numerals to designate marks (models) of ordnance until after World War II. Hence this article covers the four models of British BL 10-inch guns.
- Hogg & Thurston 1972, page 176
- Manual for Victorian naval forces 1887. HMVS Cerberus website
- David Spethman, The Garrison Guns of Australia 1788-1962 page 89, published by Ron H Mortensen, Inala, Qld, 2008. ISBN 978-0-9775990-8-0
- Text Book of Gunnery, 1902. London: Printed for His Majesty's Stationery Office, by Harrison and Sons, St. Martin's Lane
- I. V.Hogg & L. F. Thurston, British Artillery Weapons & Ammunition 1914-1918. London: Ian Allan, 1972.
- Tony DiGiulian, British 10"/32 (25.4 cm) Marks I, II, III and IV
|Wikimedia Commons has media related to BL 10 inch Mk I - IV naval gun.|
- Handbook for the 10 inch B. L. gun, 1892, 1895, 1900, 1904 at State Library of Victoria
- Instructions for 10 inch rifled breech loading Armstrong gun and automatic naval carriage and slide Describes 25-ton gun supplied to Victoria. From Australian National Archives
- Mk III disappearing mounting diagram at Victorian Forts and Artillery website
- Elswick Mk I coastal defence barbette mounting diagram at Victorian Forts and Artillery website