Military Wiki
Ordnance BL 4 inch gun Mk VII
On HMAS Australia, 1918
Type Naval gun
Place of origin United Kingdom United Kingdom
Service history
In service 1908 - 1945
Used by United Kingdom United Kingdom
Production history
Number built 600
Weight 4,704 pounds (2,130 kg) (barrel & breech)[1]
Barrel length 201.25 inches (5.112 m) bore (50.3 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 2,852 feet per second (869 m/s)[2]
Maximum range 11,600 yards (10,600 m) at 15°[3]

The BL 4-inch gun Mk VII[4] 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.[1] It was also used as a defensive weapon on Defensively Equipped Merchant Ships (DEMS) during the Second World War.[3]

Naval history

The guns armed the following warships :

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

East Africa, World War I

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]

Image gallery

Surviving examples

Gun from HMS New Zealand outside the Auckland War Memorial Museum

See also

Weapons of comparable role, performance and era


  1. 1.0 1.1 1.2 1.3 1.4 HANDBOOK for the 4" Mark VII. and VIII. B.L. Guns 1913
  2. 2852 ft/second firing a 31 lb 3 C.R.H. 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.
  3. 3.0 3.1 Campbell, Warship Volume X, p. 53.
  4. 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.
  5. Farndale 1988, page 318


External links

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