QF 2 Pounder Naval Gun - QF 2-pounder Mark II

The QF 2-pounder Mark II was essentially a scaled-up version of the QF 1 pounder Maxim gun produced by Vickers. It was a 40 mm calibre gun with a water-cooled barrel and a Vickers-Maxim mechanism. It was ordered in 1915 by the Royal Navy as an anti-aircraft weapon for ships of cruiser size and below. The original models fired from hand-loaded fabric belts, although these were later replaced by steel-link belts. This "scaling-up" process was not entirely successful, as it left the mechanism rather light and prone to faults such as rounds falling out of the belts. In 1918, one example of this weapon was experimentally mounted on the upper envelope of His Majesty's Airship 23r.

Surviving weapons were brought out of storage to see service in World War II, mainly on board ships such as naval trawlers, Motor Boats and "armed yachts". It was used almost exclusively in the single-barrel, unpowered pedestal mountings P Mark II (Royal Navy nomenclature gave mountings and guns their own distinct Mark numbers) except for a small number of weapons on the mounting Mark XV, which was a twin-barreled, powered mount. These were too heavy to be of any use at sea, and were therefore mounted ashore. All were scrapped by 1944.

• Calibre: 40 mm L/39
• Total length: 96 inches.
• Length of bore: 62 inches
• Rifling: Polygroove, plain section, 54.84 inches, uniform twist 1 in 30 inch, 12 grooves.
• Weight of gun & breech assembly: 527 lb
• Shell Weight: 2 lb (980 g). HE.
• Rate of Fire: 200 rpm
• Effective Range: 1,200 yd (1,000 m)
• Muzzle Velocity: 1920 ft/s (585 m/s)

Some 7,000 guns were made. The gun was also used by the Japanese as the 40 mm/62 "HI" Shiki.