BL 4 inch naval 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 One World War Two
Production history
No. built	600
Specifications
Weight	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 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. Of the 600 produced, 482 were still available in 1939 for use as coastal artillery and as a defensive weapon on Defensively Equipped Merchant Ships (DEMS) during the Second World War.

The guns armed the following warships :

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.

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.

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Wikipedia