BL 7.5-inch Mk VI naval gun
|Ordnance BL 7.5-inch gun Mk VI|
Coast defence gun
|Place of origin||United Kingdom|
|Used by||Royal Navy|
|Wars||World War II|
|Mass||14 tonnes (14,000 kg)|
|Barrel length||337.5 inches (8.6 m); (45 calibres)|
|Shell||200 pounds (91 kg)|
|Calibre||7.5-inch (190 mm)|
|Muzzle velocity||2,770 feet per second (844 m/s)|
|Maximum firing range||12 miles (19 km)|
The BL 7.5-inch gun Mark VI was the 45 calibre naval gun forming the main battery of Royal Navy Hawkins-class cruisers. These ships with seven single gun mounts were significant to the cruiser limitations defined by the Washington Naval Treaty.
These were built-up guns with two tubes, full-length wire winding, a jacket, and Welin breech block with hand operated Asbury mechanism. The mounting was a CP Mk V a hand-operated central pivot mount with additional power training and elevation provided by a 10HP electric motor and hydraulic pump. Elevation was +30 degrees to -5 degrees and loading was possible up to +10 degrees. The total weight of the mount including its 1in open-backed shield was 45.975 tons. They used two cloth bags each containing 14 kg (31 pounds) of cordite to fire a 200-pound (91-kg) projectile up to 19 kilometres at their maximum elevation of 30 degrees. Useful life expectancy was 650 effective full charges (EFC) per barrel.
Coast defence guns
|Range||Elevation||Time of flight||Descent||Impact velocity|
|5000 yd (4.6 km)||2° 30′||7 sec||3° 19′||1799 ft/s (548 m/s)|
|10000 yd (9.1 km)||7° 3′||17 sec||12° 32′||1218 ft/s (371 m/s)|
|15000 yd (14 km)||15° 21′||32 sec||27° 33′||1038 ft/s (316 m/s)|
|20000 yd (18 km)||27° 59′||51 sec||44° 35′||1071 ft/s (326 m/s)|
- List of naval guns
- BL 7.5-inch Mk II – V naval gun (earlier Royal Navy guns of the same calibre)
- BL 8-inch Mk VIII naval gun (used on subsequent Royal Navy heavy cruisers)
Notes and references
- Whitley 1995 pp.77–80
- Campbell 1985 p.33
- Mark VI = Mark 6. Britain used Roman numerals to denote Mark (models) of ordnance until after World War II. This was the 6th model of BL 7.5-inch naval gun.
- Preston 1980 pp.69–70
- Campbell, John (1985). Naval Weapons of World War Two. Naval Institute Press. ISBN 0-87021-459-4.
- Lenton, H.T. & Colledge, J.J (1968). British and Dominion Warships of World War Two. Doubleday and Company.
- Preston, Anthony (1980). Cruisers. Prentice-Hall. ISBN 0-13-194902-0.
- Whitley, M.J. (1995). Cruisers of World War Two. Brockhampton Press. ISBN 1-86019-874-0.
|Wikimedia Commons has media related to BL 7.5 inch Mk VI naval gun.|
- Tony DiGiulain, Britain 7.5"/45 (19 cm) Mark VI