The BL 7.5-inch gun Mark VIMark 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. was the 45

calibre In guns, particularly firearms, caliber (or calibre; sometimes abbreviated as "cal") is the specified nominal internal diameter of the gun barrel bore – regardless of how or where the bore is measured and whether the finished bore match ...

naval gun forming the main battery of

Royal Navy The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against ...

s. These ships with seven single gun mounts were significant to the cruiser limitations defined by the

Washington Naval Treaty The Washington Naval Treaty, also known as the Five-Power Treaty, was a treaty signed during 1922 among the major Allies of World War I, which agreed to prevent an arms race by limiting naval construction. It was negotiated at the Washington Nav ...

.Preston 1980 pp.69–70

Description

These were

built-up gun A built-up gun is artillery with a specially reinforced barrel. An inner tube of metal stretches within its elastic limit under the pressure of confined powder gases to transmit stress to outer cylinders that are under tension.Fairfield (1921) p. ...

s with two tubes, full-length wire winding, a jacket, and

Welin breech block The Welin breech block was a revolutionary stepped, interrupted thread design for locking artillery breeches, invented by Axel Welin in 1889 or 1890. Shortly after, Vickers acquired the British patents. Welin breech blocks provide obturation for ...

with hand-operated

Asbury mechanism An Asbury Mechanism opens and closes the breech of heavy artillery for reloading with a projectile and bags of propellant. It was widely used for naval artillery of the world wars and similar coastal artillery and railway guns. The device was inve ...

. 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 Cordite is a family of smokeless propellants developed and produced in the United Kingdom since 1889 to replace black powder as a military propellant. Like modern gunpowder, cordite is classified as a low explosive because of its slow burn ...

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

Seven guns were installed as

coastal artillery Coastal artillery is the branch of the armed forces concerned with operating anti-ship artillery or fixed gun batteries in coastal fortifications. From the Middle Ages until World War II, coastal artillery and naval artillery in the form of ...

in the Netherlands Antilles, five in

Mozambique Mozambique (), officially the Republic of Mozambique ( pt, Moçambique or , ; ny, Mozambiki; sw, Msumbiji; ts, Muzambhiki), is a country located in southeastern Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi ...

, three in Canada, and three in a battery at South Shields during the

Second World War World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposi ...

Shell trajectory

Notes and references

Bibliography

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External links