BL 12 inch railway gun

• Name — Ordnance BL 12 inch Gun Mk IX on truck, railway • Origin — United Kingdom • Type — Railway gun • Is Artillery — yes • Is Ranged — yes • Is Explosive — yes • Is Uk — yes • Service — 1915 – 1930 (Rail) • Used By — United Kingdom • Wars — First World War • Manufacturer — Woolwich Arsenal (guns) Vickers & Elswick Ordnance Company (carriage) • Production Date — 1906 (guns) • Number — 4 (Rail) • Variants — mountings Mk I, Mk II • Length — 40 ft L/40 • Cartridge — HE; 850 lb • Caliber — 12 in • Velocity — 2610 ft/s • Max Range — 32700 yd • Breech — Welin screw • Recoil — Hydro – spring, 34 in • Carriage — Railway truck • Elevation — 0° - 30° • Traverse — 1° L & R • Filling — Amatol • Filling Weight — 94 lb

Vickers mounted two Mk IX W guns on slightly different railway mountings, Mk I, from September 1915. They are both identified by the open-frame appearance, recoil buffers above the barrel and the bogies with frames between the wheels similar to locomotive bogies. One mounting has a distinctive diamond-shape from the side and has a warping winch on the front; the other's carriage has a more squared-off profile with no warping winch at the front. The weapons on the Mk I mountings were originally reserve guns for HMS Cornwallis. Elswick Ordnance Company (Armstrongs) mounted two more on its own design of Mk II railway mounting, delivered to the Western Front in August 1916. They are identified by the boxed-in frame appearance, recoil buffers below the barrel and the bogies with frames outside the wheels.

The gun cars allowed only 1° left and right traverse, achieved by pivoting the entire gun car body about the forward bogies, in the two Vickers carriages, or about the rear bogies in the Armstrong carriages. Like most railway guns in the war it was operated on specially-constructed curved sections of track and moved forward or backward to point it at a new target. Fine adjustment could then be achieved by onboard traversing, which at the gun's maximum range covered an arc of about 1,000 yd. The initial shock of firing was absorbed by a hydro-spring mechanism, allowing 34 in of recoil within the gun mounting. The remaining recoil energy was absorbed by allowing the entire railway wagon to roll backwards 40 ft (Vickers carriage) or 3 - (Armstrong carriage) against locked brakes. This "rolling recoil" system allowed the gun to be operated without the need to construct a pit with a strong static platform below the gun for it to recoil into and to allow transmission of all the recoil force directly to the ground as was typical of many large US and French railway guns.

• Illustration — Crew of 12 in railway gun on Vickers Mk I mounting, Woesten, 23 August 1917, Third Battle of Ypres At the end of World War I, the dispositions of the guns on the Western Front were: 1 gun of 92 Battery and 1 gun of 543 Battery with First Army i.e. Artois; 1 gun of 92 Battery with Third Army i.e. Somme; 1 gun of 543 Battery with Fourth Army i.e. Somme.

• Canon de 305 mm Modèle 1893/96 gun French equivalent railway gun

The following is established of the heading itself. Institutional cataloguing adds that bL 12 inch railway gun is associated with United Kingdom of Great Britain and Ireland. Institutional cataloguing adds that bL 12 inch railway gun is classified as a railway gun or rifled breech loader.