QF 12 pounder 12 cwt AA gun

• Name — Ordnance QF 12 pounder 12 cwt anti-aircraft gun • Origin — United Kingdom • Type — Anti-aircraft gun • Is Ranged — yes • Is Artillery — yes • Is Uk — yes • Service — 1914–1918 (as land AA gun) • Used By — United Kingdom Kingdom of Italy Empire of Japan • Wars — World War I World War II • Design Date — 1893 • Manufacturer — Elswick Ordnance Company Vickers • Variants — Mk I, Mk II • Caliber — 3 inch (76.2 mm) • Cartridge — Fixed or separate QF • Breech — single-motion screw • Recoil — Hydro-spring, constant, • Elevation — 0° - 85° • Traverse — 360°

When World War I began Britain had no anti-aircraft artillery and had given little thought to it. Hence in 1914 when Germany occupied parts of Belgium and northern France, it faced the risk of air attack, and various medium caliber guns were adapted to high-angle mountings, including the 12 pdr 12 cwt. All QF 12 pounder ammunition at the time was "Separate loading QF" i.e. the propellant came in a brass cartridge case with primer ready installed, but the shell was loaded separately. For anti-aircraft firing, Fixed QF rounds were quickly developed i.e. with the shell already attached to the cartridge case. This allowed slightly faster loading.

• Illustration — 12 pdr 12 cwt gun in use as improvised anti-aircraft gun on garrison mounting, Gallipoli 1915 For home air defence the gun was typically mounted on a high-angle mounting with an additional spring recuperator above the barrel, on a 2-wheel towed travelling platform, × The 4 stabilizing arms at the corners were swung out, rods at the ends screwed down to lift the platform off the wheels which were then removed and the platform lowered to the ground. It was also deployed on static mountings to defend prominent targets such as dockyards. While the gun was much lighter than the QF 3 inch 20 cwt AA gun, for anti-aircraft use it lacked its range and shell weight. Hence the 3 inch 20 cwt gun became the preferred heavy AA gun on land and ships from 1914 to 1937. The 12 pdr 12 cwt also proved only marginally superior to the much lighter QF 13 pounder 9 cwt as a light AA gun. Comparison: - • Gun — Muzzle velocity — Shell weight — Time to at 25° (seconds) — Time to at 40° (seconds) — Time to at 55° (seconds) — Max. height • 13-pdr 9 cwt — 10.1 — 15.5 — 22.1 • 12-pdr 12 cwt — 9.1 — 14.1 — 19.1 • 3-inch 20 cwt 1914 — 8.3 — 12.6 — 16.3 • 3-inch 20 cwt 1916 — 9.2 — 13.7 — 18.8 At the end of World War I, 36 guns were still in service in the home air defense of Britain, 10 on the Western Front and 2 in Mesopotamia where it was typically mounted on river barges. The gun remained in Royal Navy anti-aircraft use, in the form of the new Mk V version, on smaller ships in World War II because of its low and high angle firing.

• — • Mk II & Mk III cartridges, 1914 - original separate QF — Mk IV Common Lyddite AA shell, 1914