BL 4-inch Mk VIII naval gun

Ordnance BL-4-inch Mk VIII naval gun
Ordnance BL-4-inch Mk VIII naval gun
	Forward gun of HMS Defender
Type	Naval gun
Service history
In service	1908–1945
Used by	United Kingdom; Australia
Wars	World War I – World War II
Production history
Designed	1904
No. built	Mk VIII: 246; Mk XI: 30
Variants	Mk VIII – Mk XI
Specifications
Mass	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 Mark VIII naval gun^{[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.^[2]

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 Mark XI-variant was adapted to arm the 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

^ ^a ^b ^c ^d ^e ^f DiGiulian
^ ^a ^b ^c ^d ^e HANDBOOK for the 4" Mark VII. and VIII. B.L. Guns 1913
^ 2287 ft/second firing a 31 lb 3 CRH projectile, using 5 lb 4 oz cordite MD size 16 propellant. HANDBOOK for the 4" Mark VII. and VIII. B.L. Guns 1913.

Sources

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

External links

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

[4] 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.

[DiGiulian-1] ^ ^a ^b ^c ^d ^e ^f DiGiulian

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

[3] 2287 ft/second firing a 31 lb 3 CRH projectile, using 5 lb 4 oz cordite MD size 16 propellant. HANDBOOK for the 4" Mark VII. and VIII. B.L. Guns 1913.

[note 1]

[2]

[1]

[3]