BL 6 inch Mk XII naval gun

BL 6 inch gun Mk XII
Forward gun on cruiser HMS Galatea, February 1917
Type	Naval gun
Place of origin	United Kingdom
Service history
In service	1914 - 1945
Used by	British Empire
Wars	World War I World War II
Production history
Designer	Vickers
Designed	1913
Manufacturer	Vickers
Number built	463
Specifications
Weight	15,512 pounds (7,036 kg) barrel & breech^[1]
Barrel length	270 inches (6.858 m) bore (45 cal)^[2]

Shell	100 pounds (45.36 kg) Lyddite, Armour-piercing, Shrapnel^[3]
Calibre	6 inches (152.4 mm)
Breech	Welin interrupted screw
Recoil	Hydro-spring, 16.5 inches (420 mm)^[4]
Elevation	-7° - 30°^[5]
Muzzle velocity	2,825 feet per second (861 m/s)^[6]
Maximum firing range	19,660 metres (21,500 yd)^[7]

The BL 6 inch Gun Mark XII^[8] was a British 45 calibres naval gun which was mounted as primary armament on light cruisers and secondary armament on dreadnought battleships commissioned in the period 1914 - 1926, and remained in service on many warships until the end of World War II.

Design

This was a high-velocity naval gun consisting of inner "A" tube, "A" tube, wound with successive layers of steel wire, with a jacket over the wire.^[9]

Naval service

Single gun on CP mounting on cruiser HMS Enterprise

Experimental twin turret on HMS Enterprise, seen in 1936, which formed the prototype for twin 6-inch turrets for the Nelson-class battleships, as well as the Leander and Arethusa-class cruisers

Gunners load a casemate gun on battleship HMS Malaya, May 1943. The men at left carry cordite cartridges, still in their storage cases, on their shoulders

It superseded the 45-calibres Mk VII gun and the longer 50-calibres Mk XI gun which had proved unwieldy in light cruisers due to its length, and was Britain's most modern 6-inch naval gun when World War I began.

Guns were mounted in the following ships :

Birmingham-class light cruisers laid down 1912, commissioned 1914
Arethusa-class light cruisers laid down 1912, commissioned 1914
C-class light cruisers of 1914
M29-class monitors of 1915
Queen Elizabeth-class battleships laid down 1912, commissioned 1915
Revenge-class battleships laid down 1913, commissioned 1916
Destroyer leader HMS Swift as re-gunned in 1917
Danae-class (or D-class) light cruisers completed 1918 - 1919
Monitors HMS Raglan and HMS Abercrombie from 1918
Emerald-class (or E-class) light cruisers laid down 1918, commissioned 1926

Coast defence gun

During WWII some Mk XII guns were used in emergency coast defense batteries.^[10]

Notable actions

Ordinary Seaman John Henry Carless was posthumously awarded the Victoria Cross for heroism in serving his gun on HMS Caledon during the Second Battle of Heligoland Bight on 17 November 1917.

Ammunition

This gun generated a higher pressure in the chamber on firing compared to preceding 6-inch guns such as Mk VII and Mk XI. This necessitated use of special shells capable of withstanding a pressure of 20 tons per square inch on firing, which had "Q" suffixed to the name. World War I shells were marked "A.Q." denoting special 4 C.R.H. shells for this gun.^[1]

Mk XII A.Q.N.T. Common lyddite shell with night tracer, 1914

Surviving examples

On monitor HMS M33 at Portsmouth Historic Dockyard, UK
A gun from HMAS Adelaide at HMAS Cerberus naval base, Victoria, Australia

Notes and references

1 2 Handbook, 1917, Page 5
↑ Handbook, 1917, Page 7
↑ 100 lb shells : Treatise on Ammunition, 1915
↑ Handbook, 1917, Page 6, 23-26
↑ 30° elevation was possible with P.XIII mountings used on light cruisers; 20° elevation was possible on some P.VII* mountings used on light cruisers; 14° elevation was possible with P.IX mountings used on battleships; 15° was possible with P.VII mountings used on light cruisers. Handbook, 1917, Pages 5, 31, 41, Plates 6, 24, 35
↑ 2,825 feet per second using 27 lb 2 oz cordite MD size 19 propellant was the figure used in range tables. New guns were quoted with a muzzle velocity of 2,845 feet per second. Handbook, 1917, Page 5
↑ "Gun Model: BR 6in 45cal BL Mk XII". navalhistory. Retrieved 6 September 2014.
↑ Mark XII = Mark 12 : Britain denoted Marks (models) of guns with Roman numerals until after World War II. This was the twelfth model of British BL 6-inch gun.
↑ Handbook, 1917, page 5, 6
↑ "Britain 6"/45 (15.2 cm) BL Mark XII and Mark XX". navweapons.com. Retrieved 6 September 2014.

Bibliography

Campbell, John (January 1984). Gray, Randal, ed. "British Naval Guns, 1880–1945, No. 12". Warship (29): 30–32.
"Handbook For The 6-inch Breech Loading Mark XII. Gun" G.21117/17. Admiralty, Gunnery Branch, 1917.

External links

Wikimedia Commons has media related to BL 6 inch naval gun Mk XII.

Tony DiGiulian, British 6"/45 (15.2 cm) BL Mark XII and Mark XX

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 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 V 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 pdr 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 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 pdr 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

British Commonwealth naval weapons of the Second World War

Monitor guns	BL 15 inch

Capital ship main armament	BL 14 inch BL 15 inch BL 16 inch

Heavy cruiser main armament	BL 7.5 inch Mk VI BL 8 inch Mk VIII

Secondary armament and light cruiser main armament	QF 4 inch Mk V QF 4.5 inch QF 5.25 inch BL 6 inch Mk XII BL 6 inch Mk XXII BL 6 inch Mk XXIII

Minesweeper, Sloop, Corvette, Frigate and Destroyer armament	QF 6 pounder 10 cwt QF 12 pdr 12 cwt Mk V QF 4 inch Mk IV BL 4 inch Mk IX QF 4 inch Mk XVI QF 4 inch Mk XIX QF 4.5 inch BL 4.7 inch Mk II QF 4.7 inch Mk IX & XII QF 4.7 inch Mk XI

Submarine guns	QF 12 pdr 12 cwt Mk V QF 3 inch 20 cwt QF 4 inch Mk XII & XXII

Anti-aircraft weapons	Unrotated Projectile Holman Projector 20 mm Oerlikon QF 2 pounder "pom-pom" Mk VIII 40 mm Bofors QF 3-inch 20 cwt QF 4 inch Mk V QF 4 inch Mk XVI QF 4.5 inch QF 4.7 inch Mk VIII

Light weapons	.303 Lewis machine gun .50 Vickers Mk III machine gun QF 3 pounder Vickers

Torpedoes	21 inch Mk VII 21 inch Mk VIII 21 inch Mk X 21 inch Mk XI 24.5 inch Mk I

Anti-submarine weapons	Thornycroft depth charge thrower Hedgehog Squid

Small craft armament	Molins 6 pounder Vickers K machine gun 18 inch torpedo

Foreign-sourced weapons	20 mm Oerlikon 40 mm Bofors 3-inch 23 caliber gun (US) 3-inch 50 caliber gun (US) 4-inch 50 caliber Mark 9 gun (US) 5-inch 51 caliber Mark 8 gun (US) Y-gun depth charge projector (US) Mark 8 torpedo (US)

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