|Ordnance BL 12 inch gun Mk I - VII|
On HMS Conqueror
Coast defence gun
|Place of origin||United Kingdom|
|In service||1882 - 1920|
|Used by||Royal Navy|
|Variants||Mks I - VII|
|Weight||Mk I : 47 tons barrel & breech|
Mk II - V 45 tons
Mk VI, VII : 46 tons
|Barrel length||Mk I & II : 301.7 inches (7.663 m) bore (25.14 calibres)|
Mk III - VII 303 inches (7.696 m) bore (25.25 calibres)
|Shell||714 pounds (324 kg)|
|Calibre||12-inch (304.8 mm)|
|Muzzle velocity||1,910 feet per second (582 m/s)|
|Effective range||8,000 yards (7,300 m) at 9° 57'|
The BL 12 inch naval gun Mk I was Britain's first attempt to match the large breech-loading naval guns being installed in rival European navies, particularly France. Mks I - VII all had a barrel of approximately 303 inches in length (25.25 calibres) and similar performance.
Mk II was installed on battleships Colossus from 1882, Collingwood and the coastal service ironclad Conqueror. Mk II guns failed in service and were quickly replaced by Mks III. IV and V, with many changes and improvements. The later marks were also mounted on Hero, sistership of Conqueror, and on Edinburgh, sistership of Colossus.
Coast defence gun
Mks I, VI and VII were coast defence versions with trunnions for mounting on recoil slides. They were installed in forts in England at Spitbank Fort, No Man's Land Fort and Horse Sand Fort from 1884 onward and were in active service during World War I.
Notes and references
- Mk I = Mark 1, Mk VII = Mark 7. Britain used Roman numerals to designate marks (i.e. models) of ordnance until after World War II. Hence this article describes the first seven models of British BL 12-inch guns
- Text Book of Gunnery, 1887. Table XVI, Pages 312 - 313
- Text Book of Gunnery 1902, Table XII, Page 336
- 1910 ft/second firing a 714 lb projectile, with 295 lb Brown Prismatic powder Text Book of Gunnery, 1887. Table XVI, Page 313. Text Book of Gunnery 1902 gives muzlle velocity 1914 ft/second with 295 lb brown powder or 88 lb 8 oz cordite size 30 charge.
- Text Book of Gunnery, 1887, Table XIV, Page 308.
- Hogg & Thurston 1972, pages 188-189.
- Hogg, I.V. and Thurston, L.F. (1972). British Artillery Weapons & Ammunition 1914-1918. Ian Allan, London. ISBN 0-7110-0381-5
- Text Book of Gunnery, 1887. London: Printed for His Majesty's Stationary Office, by Harrison and Sons, St. Martin's Lane
- Text Book of Gunnery, 1902. London: Printed for His Majesty's Stationary Office, by Harrison and Sons, St. Martin's Lane
|Wikimedia Commons has media related to BL 12 inch naval gun Mk I - VII.|
- Rob Brassington, Dreadnought Project : detailed Mk IV gun description and diagrams
- Tony DiGiulian, British 12"/25 (30.5 cm) Marks I and II
- Tony DiGiulian, British 12"/25 (30.5 cm) Marks III, IV, V and Vw
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