BL 12-inch Mk VIII naval gun

Naval Gun, Coastal Defence

Ordnance BL 12-inch Mk VIII gun
Muzzle of gun on HMS Canopus, 1916
Type	Naval Gun, Coastal Defence
Place of origin	United Kingdom
Service history
In service	1895–1927
Used by	Royal Navy
Wars	World War I
Production history
Designer	Woolwich Arsenal
Manufacturer	Vickers
Variants	Mk VIII, VIIIe, VIIIv^[1]
Specifications
Mass	46 tons barrel & breech^[2]
Length	445.6 in (11.32 m)^[3]
Barrel length	35 ft 5 in (10.80 m) (35.43 calibres)^[2]

Shell	850 lb (390 kg)^[2]
Calibre	12-inch (304.8 mm)
Breech	Welin interrupted screw
Recoil	hydraulic ^[4]
Elevation	- 3 / +13.5 degrees^[3]
Traverse	+150 / -150 degrees^[3]
Rate of fire	Battleships: 1 in 70 sec. Monitors: 1 in 60 sec.^[3]
Muzzle velocity	2,367 ft/s (721 m/s)^[5]
Effective firing range	10,000 yd (9,100 m)^[2]
Maximum firing range	26,000 yd (24,000 m)^[3]

The BL 12-inch Mark VIII naval gun^{[note 1]} was one of the first large British rifled breech-loading naval guns designed for the higher pressures generated by the new cordite propellant of the 1890s, and Britain's first large wire-wound gun. It represented a major advance compared to previous British guns.

Naval service

The gun was installed on the Majestic-class battleships from 1895 and on the Canopus-class battleships from 1899. During World War I guns removed from the obsolete Majestic class were mounted in Lord Clive-class monitors for shore bombardment.

Land service

From 1921 to 1926 two guns from the decommissioned battleship HMS Illustrious were in service in the Tyne Turrets for coast defence, north and south of the mouth of the River Tyne in the northeast of England.

Problems in service

During bombardment service when mounted in the Lord Clive-class monitors deposition of copper from the projectile driving bands needed frequent removal. However, problems with the inner liners were more serious. The continual drag of the driving bands caused the liner to be gradually stretched forward. The resulting protrusion at the muzzle could simply be cut off, but in addition the liner began to form a ridge in the barrel near the shoulders of the outer ‘A’ tube, where the inner ‘A’ tube was keyed to the outer. The ridge accumulated copper from the driving bands, which could give sufficient retardation to the projectile to start the fuze, which resulted in a premature detonation either within the bore, or soon after leaving the muzzle. This happened several times during bombardment service, including an occasion when Lord Clive showered pieces of shell over the French destroyer Aventurier. The ‘steel choke’ restriction could be temporarily removed by rubbing down with an emery-covered block pulled back and forth in the bore, but the only permanent cure was to fit new guns with a modified design of liner, which had a different arrangement of internal shoulders.^[6]

Images

Y turret (aft) guns of HMS Hannibal.
Forward guns of HMS Ocean
HMS Canopus bombarding Turkish forts, Dardanelles March 1915. Photo by Ernest Brooks.
The battleship HMS Illustrious fires her 12-inch (305 mm) Mark VIII guns during gunnery practice.
The starboard 12-inch (305 mm) Mark VIII gun in one of the turrets aboard the battleship HMS Illustrious. The gun's breech is open.
The starboard 12-inch (305 mm) Mark VIII gun in one of the turrets aboard the British battleship HMS Caesar. The gun's breech is closed.

Notes

^ Mark VIII = Mark 8. Britain used Roman numerals to denote marks (models, abbreviated Mk) of ordnance until after World War II. Hence this was the 8th model of British 12-inch breech-loading naval guns,

References

^ Mk VIII was the original Naval design; Mk VIIIe and VIIIv were reserve guns manufactured in 1906 by Elswick Ordnance and Vickers respectively. Hogg & Thurston 1972, page 190. These incorporated changes to correct a steel choke problem (DiGiulian)
^ ^a ^b ^c ^d Text Book of Gunnery 1902, Table XII Page 336
^ ^a ^b ^c ^d ^e "12"/35 (30.5 cm) Mark VIII". Retrieved 24 August 2022.
^ Hodges, p. 40
^ 850 lb shell, with 174 lb cordite propellant. Text Book of Gunnery 1902, Table XII page 336
^ Buxton, Ian (2008). Big Gun Monitors: Design, Construction and Operations, 1914–1945 (2 ed.). Seaforth Publishing, Pen and Sword Books Ltd, Sth Yorkshire S70 2AS, Great Britain. p. 224. ISBN 978-1-59114-045-0.

Bibliography

Text Book of Gunnery Archived 12 July 2012 at archive.today, 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 12"/35 (30.5 cm) Mark VIII

External links

Wikimedia Commons has media related to BL 12 inch Mk VIII naval gun.

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v t e British Empire naval weapons of the First World War
Monitor guns	BL 9.2-inch Mk VI BL 9.2-inch Mk VIII BL 9.2-inch Mk X BL 9.2-inch Mk XII BL 12-inch Mk VIII BL 14-inch Mk II (US built) BL 15-inch Mk I BL 18-inch Mk I
Capital ship main armament	Vickers 10-inch 45 cal. EOC 10-inch 45 cal. BL 12-inch Mk VIII BL 12-inch Mk IX BL 12-inch Mk X BL 12-inch Mk XI & XII EOC 12-inch 45 cal. Mk XIII BL 13.5-inch Mk I – IV BL 13.5-inch Mk V BL 13.5-inch Mk VI EOC 14-inch 45 cal. Mk I BL 15-inch Mk I
Armoured cruiser main armament	BL 7.5-inch Mk I BL 9.2-inch Mk X BL 9.2-inch Mk XI
Secondary armament and light cruiser main armament	QF 12-pounder 18 cwt QF 14-pounder Maxim-Nordenfelt QF 14-pounder Mk I & II QF 4-inch Mk III BL 4-inch Mk VII QF 4-inch Mk V BL 4-inch Mk IX BL 5.5-inch Mk I QF 6-inch Mk I – III BL 6-inch Mk VII BL 6-inch Mk XI BL 6-inch Mk XII BL 6-inch Mk XIII-XVIII BL 7.5-inch Mk II – Mk V
Destroyer and small cruiser armament	QF 12-pounder 12 cwt Mk II QF 4-inch Mk III BL 4-inch Mk VIII QF 4-inch Mk IV BL 4.7-inch Mk I
Merchant ship armament	QF 4.7-inch Mk I – IV QF 4.7-inch Mk V*
Submarine guns	BL 4-inch Mk XI QF 4-inch Mk XII
Anti-aircraft guns	QF 2-pounder "pom-pom" Mk II QF 3-inch 20 cwt QF 4-inch Mk V
Light weapons	.303 Vickers machine gun QF 3-pounder Hotchkiss QF 3-pounder Vickers QF 6-pounder Hotchkiss
Torpedoes	18-inch Mk V – VIII 21-inch Mk II 21-inch Mk IV
Mines	Spherical Mk I, II and III Vickers Elia mine Type H mine
Anti-submarine weapons	Type A Depth charge Type B Depth charge Type C Depth charge Type D Depth charge Type E Depth charge Type F Depth charge Type G Depth charge Cruiser Mine 7.5-inch howitzer
Landing guns	QF 12-pounder 8 cwt