| 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 I World War II |
| Production history | |
| No. built | 600[1] |
| Specifications | |
| Mass | 4,704 pounds (2,130 kg) (barrel & breech)[2] |
| Barrel length | 201.25 inches (5.112 m) bore (50.3 calibres)[2] |
| Shell | 31 pounds (14.06 kg) Common pointed, Common lyddite[2] |
| Calibre | 4 inches (101.6 mm) |
| Breech | Welin, Single-motion screw[2] |
| Elevation | -10 degrees to +15 degrees[1] |
| Rate of fire | 6-8 rpm |
| Muzzle velocity | 2,852 feet per second (869 m/s)[3] |
| Maximum firing range | 11,600 yards (10,600 m) at 15°[4] |
The BL 4-inch gun Mk VII[note 1] 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.[2] Of the 600 produced, 482 were still available in 1939[1] for use as coastal artillery and as a defensive weapon on Defensively Equipped Merchant Ships (DEMS) during the Second World War.[4]
- ^ a b c Campbell, Naval Weapons of WWII, p. 43.
- ^ a b c d e HANDBOOK for the 4" Mark VII. and VIII. B.L. Guns 1913
- ^ 2852 ft/second firing a 31 lb 3 CRH 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.
- ^ a b Campbell, Warship Volume X, p. 53.
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