BL 12-inch Mk XI – XII naval gun

BL 12-inch Mk XI and Mk XII gun
BL 12-inch Mk XI and Mk XII gun
	Aft Mk XII guns of HMS Hercules
Type	Naval gun
Place of origin	United Kingdom
Service history
In service	1910–1922
Wars	World War I
Production history
Designer	Vickers
Manufacturer	Vickers Armstrong Whitworth Coventry Ordnance Works William Beardmore and Company
Specifications
Barrel length	50 ft (15.24 m) bore (50 calibers)
Shell	850 lb (385.6 kg) Lyddite, Armour-piercing, Shrapnel[1]
Calibre	12 inches (304.8 mm)
Muzzle velocity	2,825 ft/s (861 m/s)[2]
Maximum firing range	19,380 m (21,190 yd)[3]

The BL 12-inch Mark XI and Mark XII gun[note 1] were British breech loading (BL) naval guns of 50-calibres length mounted as primary armament on dreadnought battleships from 1910.

History

Vice-Admiral Doveton Sturdee in front of the Mk XII guns of a wing turret on HMS Hercules

In an effort to increase the armour-piercing capability and range of a 12-inch gun, the 50 calibres/600 inches Mk XI's barrel was 5 calibres/60 inches longer than the previous Mk X gun's 45 calibres. As a result, muzzle velocity increased from 2,700 feet per second (820 m/s) to 2,825 feet per second (861 m/s), but bore erosion, which led to short barrel life, and poor accuracy due to inconsistent cordite propellant burning, hampered the gun. The Mk XII derived from it suffered from the same problems.

Instead of attempting to improve their 12-inch gun, the British developed the 13.5-inch Mk V gun of 45-calibres, which could achieve greater range at lower muzzle velocities due to its larger shell.

Mk XI guns were mounted on:

St. Vincent-class battleships laid down 1907, commissioned 1910
HMS Neptune laid down 1909, commissioned 1911

Mk XII guns were mounted on:

Colossus-class battleships laid down 1909, commissioned 1911

Notes

Britain used Roman numerals to denote Marks (models) of ordnance until after World War II. These were the eleventh and twelfth models of BL 12-inch guns.

References

850 lb shells : Treatise on Ammunition, 1915
2825 ft/second with 4 CRH 850 lb projectile : As quoted in Range Tables for His Majesty's Fleet, Vol. I., 1918 9.2-Inch Guns and Above April, 1918 2825 ft/second using 307 lb cordite MD size 45 propellant : Treatise on Ammunition, 1915
"Gun Model: BR 12in 50cal Mk XI XI* XII". Retrieved 8 June 2023.

Bibliography

Tony DiGiulian, British 12"/50 (30.5 cm) Marks XI, XI* and XII

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[4] Britain used Roman numerals to denote Marks (models) of ordnance until after World War II. These were the eleventh and twelfth models of BL 12-inch guns.

[1] 850 lb shells : Treatise on Ammunition, 1915

[2] 2825 ft/second with 4 CRH 850 lb projectile : As quoted in Range Tables for His Majesty's Fleet, Vol. I., 1918 9.2-Inch Guns and Above April, 1918 2825 ft/second using 307 lb cordite MD size 45 propellant : Treatise on Ammunition, 1915

[3] "Gun Model: BR 12in 50cal Mk XI XI* XII". Retrieved 8 June 2023.

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 US 14-inch 45 cal. 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

BL 12-inch Mk XI – XII naval gun

History

See also

Weapons of comparable role, performance and era

Notes

References

Bibliography