BL 7.5-inch Mk VI naval gun

Ordnance BL 7.5-inch gun Mk VI
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
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^[3] 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.^[4]

Description

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.^[2]

Coast defence guns

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.^[2]

Shell trajectory

Range^[2]	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)

Notes and references

↑ Whitley 1995 pp.77–80
1 2 3 4 5 6 7 8 9 10 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

Bibliography

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, Antony (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.

External links

Tony DiGiulain, Britain 7.5"/45 (19 cm) Mark VI

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[Whitley-1] Whitley 1995 pp.77–80

[Campbell-2] 1 2 3 4 5 6 7 8 9 10 Campbell 1985 p.33

[3] 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-4] Preston 1980 pp.69–70

[1]

[2]

[3]

[4]

British Commonwealth naval weapons of the Second World War
Monitor guns	BL 15-inch
Capital ship main armament	BL 14-inch BL 15-inch BL 16-inch
Heavy cruiser main armament	BL 7.5-inch Mk VI BL 8-inch Mk VIII
Secondary armament and light cruiser main armament	QF 4-inch Mk V QF 4.5-inch QF 5.25-inch BL 5.5-inch BL 6-inch Mk XII BL 6-inch Mk XXII BL 6-inch Mk XXIII
Minesweeper, Sloop, Corvette, Frigate and Destroyer armament	QF 6-pounder 10 cwt QF 12-pounder 12 cwt Mk V QF 4-inch Mk IV BL 4-inch Mk IX QF 4-inch Mk XVI QF 4-inch Mk XIX QF 4.5-inch BL 4.7-inch Mk II QF 4.7-inch Mk IX & XII QF 4.7-inch Mk XI
Submarine guns	QF 12-pounder 12 cwt Mk V QF 3-inch 20 cwt QF 4-inch Mk XII & XXII
Anti-aircraft weapons	Unrotated projectile Holman Projector 20 mm Oerlikon QF 2-pounder "pom-pom" Mk VIII 40 mm Bofors QF 3-inch 20 cwt QF 4-inch Mk V QF 4-inch Mk XVI QF 4.5-inch QF 4.7-inch Mk VIII
Light weapons	.303 Lewis machine gun .50 Vickers Mk III machine gun QF 3-pounder Vickers
Torpedoes	21-inch Mk VII 21-inch Mk VIII 21-inch Mk X 21-inch Mk XI 24.5-inch Mk I
Anti-submarine weapons	Thornycroft depth charge thrower Hedgehog Squid
Small craft armament	Molins 6-pounder Vickers K machine gun 18-inch torpedo
Foreign-sourced weapons	20 mm Oerlikon 40 mm Bofors 3-inch 23 caliber gun (US) 3-inch 50 caliber gun (US) 4-inch 50 caliber Mark 9 gun (US) 5-inch 51 caliber Mark 8 gun (US) Y-gun depth charge projector (US) Mark 8 torpedo (US)

British Commonwealth artillery of World War II
Tank guns	QF 2-pounder QF 3-pounder QF 6-pounder QF 75 mm QF 3-inch howitzer QF 17-pounder 77 mm HV QF 95 mm howitzer
Anti-tank guns	QF 2-pounder QF 6-pounder QF 17-pounder
Field guns and howitzers	75 mm Gun M1917 QF 18-pounder 25-pounder Gun-Howitzer 25-pounder Short QF 4.5-inch howitzer
Medium and heavy guns and howitzers	BL 4.5-inch medium field gun BL 60-pounder gun BL 5.5-inch medium gun BL 6-inch howitzer BL 6-inch gun Mk XIX 155 mm Long Tom BL 7.2-inch howitzer BL 8-inch howitzer BL 9.2-inch howitzer 240 mm howitzer M1
Mountain guns	75mm Pack howitzer M1 3.7-inch mountain howitzer
Mortars	SBML 2-inch mortar ML 3-inch mortar ML 4.2-inch mortar
Anti-aircraft weapons	Z Battery 20 mm Oerlikon 20 mm Polsten QF 1½-pounder Mk III QF 2-pounder naval gun Bofors 40 mm QF 3-inch QF 3.7-inch QF 4.5-inch Mk II QF 5.25-inch Mk II
Coast defence	QF 6-pounder 10 cwt QF 12-pounder QF 4.7-inch Mk I–IV BL 6-inch Mk VII & Mk XXIV BL 7.5-inch Mk VI BL 8-inch Mk VIII BL 9.2-inch Mk X BL 14-inch Mk VII BL 15-inch Mk I
Railway artillery	BL 9.2-inch Mk XIII railway gun BL 12-inch Mk V railway howitzer BL 13.5-inch Mk V railway gun BL 18-inch railway howitzer