BL 4 inch naval gun Mk VIII
| Ordnance BL 4 inch gun Mk VIII | |
|---|---|
Forward gun of HMS Defender
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| 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 | |
| Weight | 2,912 pounds (1,320 kg) (barrel & breech) |
| Barrel length | 159.2 inches (4.044 m) bore (40 calibres) |
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| 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 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.
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 :
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.
A Mk XI variant was adapted to arm submarines :
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Wikipedia