BL 4 inch naval gun Mk VIII

Ordnance BL 4 inch gun Mk VIII
Forward gun of HMS Defender
Type	Naval gun
Service history
In service	1908 - 1945
Used by	United Kingdom Australia
Specifications
Weight	2,912 pounds (1,320 kg) (barrel & breech)^[1]
Barrel length	159.2 inches (4.044 m) bore (40 calibres)^[1]

Shell	31 pounds (14.06 kg) Common pointed, Common lyddite^[1]
Calibre	4 inches (101.6 mm)
Breech	Welin, single-motion screw^[1]
Muzzle velocity	2,287 feet per second (697 m/s)^[2]
Maximum firing range	10,210 yards (9,340 m)^[3]

The BL 4-inch gun Mark VIII^{[note 1]} was a British medium-velocity wire-wound naval gun introduced in 1908 as an anti-torpedo boat gun in smaller ships whose decks could not support the strain of the heavier and more powerful Mk VII gun.^[1]

Mk VIII History

Breech of gun on HMAS Huon in March 1919

The gun succeeded the QF 4 inch Mk III, whose 25-pound (11 kg) shell had been considered insufficiently powerful for its intended role. The BL Mk VIII fired a 31-pound (14 kg) shell. It armed the following warships :

HMS Swift laid down 1905
Tribal-class destroyers from HMS Saracen (1908) onwards.
Beagle-class destroyer of 1909
Acorn-class destroyers of 1910
Acheron-class destroyers of 1910
River-class torpedo-boat destroyers (Australia) of 1910.

The gun was succeeded in its class from 1911 by the QF 4 inch Mk IV.

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

Mk XI submarine gun

A Mk XI variant was adapted to arm submarines :

K-class submarines laid down 1915

Notes

↑ Mark VIII = Mark 8. Mark XI = Mark 11. Britain used Roman numerals to denote marks (models) of ordnance until after World War II. This was the eighth model of British BL 4-inch gun.

References

1 2 3 4 5 HANDBOOK for the 4" Mark VII. and VIII. B.L. Guns 1913
↑ 2287 ft/second firing a 31 lb 3 C.R.H. projectile, using 5 lb 4 oz cordite MD size 16 propellant. HANDBOOK for the 4" Mark VII. and VIII. B.L. Guns 1913.
↑ DiGiulian

Bibliography

HANDBOOK for the 4" Mark VII. and VIII. B.L. Guns 1913 (Corrected to September 1913.) ADMIRALTY Gunnery Branch, G.8652/13

External links

Wikimedia Commons has media related to BL 4 inch Mk VIII naval gun.

Tony DiGiulian, British 4"/40 (10.2 cm) BL Mark VIII and Mark XI

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

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