QF 6-pounder 6 cwt Hotchkiss

This article is about the World War I tank gun. For other 6-pounder weapons, see 6-pounder gun.

QF 6 pounder 6 cwt Hotchkiss Mk 1 - 2
Mark V tank showing short 6 pounder gun barrel
Type	Tank gun Armoured Train gun
Place of origin	United Kingdom
Service history
In service	1917 - 1944
Used by	United Kingdom
Wars	World War I World War II
Production history
Designer	Hotchkiss
Specifications
Barrel length	Bore: 52.12 inch (1.32 m) 23 calibres Total: 60 inch (1.52 m)
Shell	Fixed QF, HE 6 lb (2.7 kg)
Calibre	2.244 in (57 mm)
Breech	Vertical sliding block
Recoil	Hydro-spring
Muzzle velocity	1,350 ft/s (411 m/s)
Effective firing range	7,300 yards (6,675 m)

The Ordnance QF 6-pounder 6 cwt Hotchkiss Mk I and Mk II was a shortened version of the original QF 6 pounder Hotchkiss naval gun, and was developed specifically for use in the sponsons of the later Marks of British tanks in World War I, from Mark IV onwards.

History

World War I

Closeup of Mk I gun in Mk V tank at Imperial War Museum London

The original QF 6 pounder naval gun had turned out to be too long for practical use with the current British heavy tank designs, which mounted guns in sponsons on the side rather than turrets on top as modern tanks do. The muzzles of the long barrels sometimes dug into the mud or struck obstacles when the vehicle crossed trenches or shell craters. The shortened QF 6 pounder 6 cwt Mk I of single tube construction was introduced in January 1917 in the Mark IV tank, and may be considered the world's first specialised tank gun.

The shortened barrel incurred a reduction in muzzle velocity, but as tank guns in World War I were used against unarmoured or lightly armoured targets such as machine gun nests and artillery pieces at relatively short ranges of a few hundred yards, this was not a major disadvantage.

The Mk II gun was developed at the same time, having a built-up barrel construction.

World War II

File:Polish troops in armoured train UK 1941 IWM H 7033.jpg

Polish troops manning an armoured train with a 6-pounder in its original tank mounting at the end, Scotland February 1941

The gun was reused in the Second World War, being fitted to the 12 Armoured Trains operated in the United Kingdom. Just as with the tank mounting, the short barrel was an advantage, preventing fouling of line-side structures and bridges. The last British armoured trains (in Scotland) were decommissioned in 1944.

See also

• List of tank main guns

Bibliography

• I.V. Hogg and L.F. Thurston, British Artillery Weapons & Ammunition 1914-1918. London: Ian Allan, 1972. ISBN 978-0-7110-0381-1