BL 8 inch Mk I - VII naval gun
| Ordnance BL 8 inch gun Mks I - VII | |
|---|---|
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| Type |
Naval gun Coast defence gun |
| Place of origin | United Kingdom |
| Service history | |
| In service | 1884 - 190? |
| Used by |
 United KingdomColonial navies of Australia  New Zealand Singapore
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| Production history | |
| Designer | Mk I, VI : RGF Mk VII : EOC |
| Manufacturer | Mk I, III, IV : RGF Mk III, IV, VI, VII EOC |
| Unit cost | £6,015 |
| Variants | Mks III, IV, VI, VII, VIIA |
| Specifications | |
| Weight | Mk III & VI : 14 tons Mk IV : 15 tons Mk VII : 12 tons Mk VIIA : 13 tons barrel & breech |
| Barrel length | Mk III : 201 inches (5,105 mm) Mk VII : 204 inches (5,182 mm) Mk IV & VI : 237 inches (6,020 mm) bore |
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| Shell | Mks III, IV, VI : 210 pounds (95.25 kg) Mk VII : 180 pounds (81.65 kg) |
| Calibre | 8-inch (203.2 mm) |
| Muzzle velocity | Mk III : 1,953 feet per second (595 m/s) Mk IV & VI : 2,150 feet per second (655 m/s) Mk VII : 2,000 feet per second (610 m/s) |
| Maximum firing range | 8,000 yards (7,300 m) |
The BL 8 inch guns Mark I to Mark VII were the first generations of British rifled breechloaders of medium-heavy calibre. They were initially designed for gunpowder propellants and were of both 25.5 and 30 calibres lengths.
Mks I and II were several early proof guns that did not enter British service and Mk V was not made. Limited numbers of 25.5 and 30 calibres guns were produced.
By 1885 the Royal Navy abandoned the 8-inch gun in favour of the 9.2 inch and later the 7.5 inch gun for cruisers, until 1923 when the restrictions of the Washington Naval Treaty led Britain to develop the Mk VIII 8-inch gun in order to arm heavy cruisers with the largest gun allowed by the Treaty.
In the interim Elswick Ordnance continued to develop 8-inch guns in 40 calibre and 45-calibre lengths for export, mainly to Japan.
Mk III were low-powered 25-calibres guns mounted on :
Mk IV were 30-calibres guns mounted in :
Mk VI were 30 calibres guns mounted in :
Mk VII were lighter 25-calibres low-powered guns firing a lighter 180-pound projectile used to equip Australian colonial navies and Australian and New Zealand coastal defences in response to expected Russian expansionism in the Pacific (The "Russian scares" of the 1880s).
Mk VII guns armed the following Australian colonial gun vessels :
Mk VII guns were installed on disappearing mountings in Australia and New Zealand as coast-defence guns during the "Russian scares" of the 1880s. In the event, no Russian invasion occurred and the guns were rarely if ever fired.
Four Mk VII coast defence guns were installed at Singapore in the 1880s-1890s : two atop Mount Serapong and two at Fort Tanjong Katong.
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Wikipedia