BL 7.5 inch Mk VI naval gun

Ordnance BL 7.5 inch gun Mk VI
Gun on HMS Frobisher off the south coast of England, 5 June 1944, 12 hours before D-Day
Type	Naval gun Coast defence gun
Place of origin	United Kingdom
Service history
In service	1919–1945
Used by	Royal Navy
Wars	World War II
Production history
No. built	44
Specifications
Weight	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.

Seven guns were installed as coastal artillery in the Netherlands Antilles, five in Mozambique, three in Canada, and three in a battery at South Shields during the Second World War.