QF 6 pounder 10 cwt gun

6-pdr / 10cwt QF Mark I
The 6-pounder gun mark I in twin mark I mounting on board HMS Mackay whilst she is at Harwich.
Type	Naval gun and Coastal gun
Place of origin	United Kingdom
Service history
Used by	British Commonwealth
Wars	Second World War
Production history
Variants	Naval gun (twin mount) Coastal gun (twin mount)
Specifications
Weight	1,060 lb (481 kg)
Length	9 ft (2.787 m)
Barrel length	47 calibres
Crew	6
Calibre	57 millimetres (2.24 in)
Recoil	12 inches
Elevation	-10/+80
Traverse	360 degrees
Rate of fire	18 rounds per minute
Effective firing range	11,300 yards (10,330 m) @45°

The British QF (quick-firing) 6 pounder 10 cwt gun was a 57 mm twin-mount light coast defence and naval gun from the 1930s to 1950s.

Following the emergence of small fast attack craft during World War I, it was decided that the British Royal Navy Dockyards were vulnerable to attack by motor torpedo boats which had the speed to evade the heavy coast defence guns which defended them. In 1925, a design was adopted for a twin barrelled weapon capable of sustained semi-automatic fire. Both barrels of the weapon could be fired singly or they could be combined. The pedestal mounting and the gun crew were enclosed to the front, sides and top in a reinforced-steel barbette.

The first trials took place in 1928 with production beginning at the Woolwich Ordnance Factory in 1933. Formal War Office acceptance occurred on 28 February 1934. A coastal-defence trial using the gun and barbette was conducted at Culver Battery on the Isle of Wight in 1936. As the shadow of Second World War approached, food equipment and machinery manufacturer, Baker Perkins, was asked to take over production in March 1939; the first guns left its Westwood, Peterborough factory in March 1941.

The Mark II version of the QF 6 pounder had a barrel (made from a single forging) instead of a lined barrel in the Mark Is.

The first twin 6-pounders were installed at Singapore in 1937. The first UK installation was at Eastern Arm Battery in Dover, just before the outbreak of World War II. Also in 1939, nine pairs of guns were installed in Fort St. Elmo and Fort Ricasoli in the Grand Harbour at Valletta, Malta. These were to play a vital role in the successful defence against an attack by nineteen Italian MAS fast attack boats on 26 July 1941, when five enemy boats were sunk in less than two minutes. By the end of 1942, 155 of these weapons had been produced for 31 locations worldwide. The pair installed in 1944 at Fort Rodd Hill at Esquimalt Harbour, British Columbia is thought to be the last in existence.