BL 4 inch naval gun Mk VIII
|Ordnance BL 4 inch gun Mk VIII|
Forward gun of HMS Defender
|In service||1908 - 1945|
|Used by||United Kingdom
|Wars||World War I - World War II|
|No. built||Mk VIII: 246
Mk XI: 30
|Variants||Mk VIII - Mk XI|
|Weight||2,912 pounds (1,320 kg) (barrel & breech)|
|Barrel length||159.2 inches (4.044 m) bore (40 calibres)|
|Shell||31 pounds (14.06 kg) Common pointed, Common lyddite|
|Calibre||4 inches (101.6 mm)|
|Breech||Welin, single-motion screw|
|Elevation||-10° to +20°|
|Rate of fire||6-8 RPM|
|Muzzle velocity||2,287 feet per second (697 m/s)|
|Maximum firing range||10,210 yards (9,340 m)|
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.
Mk VIII History
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.
Mk XI submarine gun
A Mk XI variant was adapted to arm submarines :
- K-class submarines laid down 1915
- 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.
- 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.
- HANDBOOK for the 4" Mark VII. and VIII. B.L. Guns 1913 (Corrected to September 1913.) ADMIRALTY Gunnery Branch, G.8652/13
|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