QF 2-pounder naval gun

QF 2 pdr Mark VIII ("pom-pom")
Quadruple 2 pdr MK VIII guns on Mk.VII mounting aboard HMAS Nizam August 1941
Type	Autocannon
Place of origin	United Kingdom
Service history
In service	1917–1940s (Mk II) 1930–1940s (Mk VIII)
Used by	British Empire Japan Thailand Russian Empire Kingdom of Italy Netherlands
Wars	First World War Second World War
Production history
Designer	Vickers Armstrongs
Designed	1915 (Mk II) 1923 (Mk VIII)
Variants	Low-velocity (LV) & high-velocity (HV) RHI, LHI, RHO, LHO for multiple mountings Type 91 HI Shiki (Japanese)
Specifications (Mk.VIII HV)
Mass	850 lb (390 kg)
Length	8 ft 6 in (2.59 m)
Shell	40×158mmR
Calibre	40 mm (1.6 in)
Barrels	1, 4 or 8
Rate of fire	115 rpm
Muzzle velocity	new gun: 732 m/s (2,400 ft/s) worn gun: 701 m/s (2,300 ft/s)[1]
Effective firing range	3,960 m (13,300 ft) A/A ceiling
Maximum firing range	6,220 m (20,400 ft) at 701 m/s (2,300 ft/s)[2]
Feed system	14-round steel-link belt
Filling weight	71 g (2.5 oz)

The 2-pounder gun, officially the QF 2-pounder (QF denoting "quick firing") and universally known as the pom-pom, was a 40 mm (1.6 in) British autocannon, used as an anti-aircraft gun by the Royal Navy.^{[note 1]} The name came from the sound that the original models make when firing. This QF 2-pounder was not the same gun as the Ordnance QF 2-pounder, used by the British Army as an anti-tank gun and a tank gun, although they both fired 2 lb (0.91 kg), 40 mm (1.6 in) projectiles.

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