BL 4-inch Mk VII naval gun

Ordnance BL 4-inch gun Mk VII
Ordnance BL 4-inch gun Mk VII
	On HMAS Australia, 1918
Type	Naval gun
Place of origin	United Kingdom
Service history
In service	1908–1945
Used by	United Kingdom
Wars	World War I; World War II
Production history
No. built	600
Specifications
Mass	4,704 pounds (2,130 kg) (barrel & breech)
Barrel length	201.25 inches (5.112 m) bore (50.3 calibres)
Shell	31 pounds (14.06 kg) Common pointed, Common lyddite
Calibre	4 inches (101.6 mm)
Breech	Welin, Single-motion screw
Elevation	-10 degrees to +15 degrees
Rate of fire	6-8 rpm
Muzzle velocity	2,852 feet per second (869 m/s)
Maximum firing range	11,600 yards (10,600 m) at 15°

The BL 4-inch gun Mk VII^{[note 1]} was a British high-velocity naval gun introduced in 1908 as an anti-torpedo boat gun in large ships, and in the main armament of smaller ships.^[2] Of the 600 produced, 482 were still available in 1939^[1] for use as coastal artillery and as a defensive weapon on Defensively Equipped Merchant Ships (DEMS) during the Second World War.^[4]

Naval history

The guns armed the following warships :

Bellerophon-class battleships, laid down 1906
St. Vincent-class battleships, laid down 1907
Boadicea-class scout cruisers, laid down 1907
HMS Neptune, laid down 1909
Colossus-class battleships, laid down 1909
Indefatigable-class battlecruisers, laid down 1909
Orion-class battleships, laid down 1909
Lion-class battlecruisers, laid down 1909
Bristol-class light cruisers, laid down 1909
Blonde-class scout cruisers, laid down 1909
Active-class scout cruisers, laid down 1910
King George V-class battleships, laid down 1911

An example on a "DEMS" (defensively equipped merchant ship), 1943

The gun was succeeded in the "heavy" 4-inch class on new warships commissioned from 1914 onwards by the QF 4-inch Mk V. This new generation of warships were more heavily armed, and the BL Mk VII's role as secondary armament on capital ships and primary armament on cruisers was taken over by the BL 6-inch Mk VII and BL 6-inch Mk XII while the 4-inch calibre became the secondary armament on cruisers and primary armament on destroyers.

In World War II many guns were used to arm merchant ships.

World War I field gun service

A battery of 4 guns mounted on field carriages was first deployed with the South African Heavy Artillery in the German South West Africa campaign in 1915 and returned to England in September. They were then deployed in the East African Campaign from February 1916 with 11th Heavy Battery (renumbered 15th Battery from April 1916) manned by the Royal Marine Artillery.^[5]

Surviving examples

Gun from HMS *New Zealand* outside the Auckland War Memorial Museum.

2 Mk VII guns from HMS New Zealand outside the Auckland War Memorial Museum

Notes

^ Mk VII = Mark 7. Britain used Roman numerals to denote Marks (models) of ordnance until after World War II. Mark VII indicates this was the seventh model of BL 4-inch gun.

References

^ ^a ^b ^c Campbell, Naval Weapons of WWII, p. 43.
^ ^a ^b ^c ^d ^e HANDBOOK for the 4" Mark VII. and VIII. B.L. Guns 1913
^ 2852 ft/second firing a 31 lb 3 CRH projectile, using 9 lb 5 oz 15 drams cordite MD size 16 propellant. HANDBOOK for the 4" Mark VII. and VIII. B.L. Guns 1913.
^ ^a ^b Campbell, Warship Volume X, p. 53.
^ Farndale 1988, page 318

Sources

HANDBOOK for the 4" Mark VII. and VIII. B.L. Guns 1913 (Corrected to September 1913.) ADMIRALTY Gunnery Branch, G.8652/13
Campbell, John (1987). Lambert, Andrew D. (ed.). "British Naval Guns, 1880–1945, No. 17". Warship. 10: 53–55.
DiGiulian, Tony. British 4"/50 (10.2 cm) BL Mark VII
Farndale, General Sir Martin. History of the Royal Regiment of Artillery : Forgotten Fronts and the Home Base 1914–18. London:The Royal Artillery Institution, 1988
Campbell, John (1985). Naval Weapons of World War II. Naval Institute Press. ISBN 0-87021-459-4.

[5] Mk VII = Mark 7. Britain used Roman numerals to denote Marks (models) of ordnance until after World War II. Mark VII indicates this was the seventh model of BL 4-inch gun.

[Campbell,_p._43-1] Campbell, Naval Weapons of WWII, p. 43.

[Handbook1913-2] HANDBOOK for the 4" Mark VII. and VIII. B.L. Guns 1913

[3] 2852 ft/second firing a 31 lb 3 CRH projectile, using 9 lb 5 oz 15 drams cordite MD size 16 propellant. HANDBOOK for the 4" Mark VII. and VIII. B.L. Guns 1913.

[Warship53-4] Campbell, Warship Volume X, p. 53.

[6] Farndale 1988, page 318

[1]

[2]

[3]

[4]

[note 1]

[5]

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

v t e British Empire artillery of the First World War
Armoured vehicle guns	QF 3-pounder Vickers QF 6-pounder Hotchkiss QF 6-pounder 6 cwt
Infantry guns	1.59-inch breech-loading Vickers Q.F. gun, Mk II
Field artillery	BL 12-pounder 6 cwt QF 12-pounder 8 cwt QF 12-pounder 18 cwt QF 13-pounder BL 15-pounder BLC 15-pounder QF 15-pounder QF 18-pounder QF 4-inch gun Mk III BL 4-inch gun Mk VII QF 4.5-inch howitzer
Medium & heavy artillery	QF 4.7-inch gun BL 5-inch howitzer BL 5.4-inch howitzer BL 60-pounder gun BLC 6-inch siege gun BL 6-inch gun Mk VII BL 6-inch gun Mk XIX BL 6-inch 26 cwt howitzer BL 6-inch 30 cwt howitzer BL 8-inch howitzer Mk I – V BL 8-inch howitzer Mk VI – VIII
Siege artillery	BL 7.5-inch Mk III naval gun BL 9.2-inch howitzer BL 9.2-inch Mk X naval gun BL 12-inch howitzer BL 12-inch Mk X naval gun BL 15-inch howitzer
Mountain artillery	RML 2.5-inch mountain gun BL 10-pounder mountain gun BL 2.75-inch mountain gun QF 2.95-inch mountain gun QF 3.7-inch mountain howitzer
Mortars	Garland trench mortar 3-inch Stokes mortar Vickers 1.57-inch mortar 2-inch medium mortar Newton 6-inch mortar 9.45-inch Heavy Mortar
Smoke and chemical weapons	4-inch Stokes Mortar Livens Projector Livens Large Gallery Flame Projector
Anti-aircraft guns	QF 1-pounder pom-pom QF 2-pounder "pom-pom" Mk II 75 mm AA gun QF 12-pounder 12 cwt QF 13-pounder 6 cwt QF 13-pounder Mk IV QF 13-pounder 9 cwt QF 3-inch 20 cwt QF 18-pounder QF 4-inch Mk V
Coastal artillery	QF 12-pounder 12 cwt QF 4-inch naval gun Mk I – III BL 6-inch Mk VII naval gun BL 9.2-inch Mk IX – X naval gun RML 9-inch
Railway guns	BL 9.2-inch railway gun BL 12-inch railway gun BL 12-inch railway howitzer BL 14-inch railway gun