Mauser 1918 T-Gewehr

The Mauser 13 mm anti-tank rifle (, usually abbreviated T-Gewehr ) was the world's first anti-tank rifle, i.e. the first rifle designed for the sole purpose of destroying armored targets and the only anti-tank rifle to see service in World War I. Approximately 15,800 were produced.

History
It was a German weapon of World War I, appearing in February 1918. The Mauser Company began mass production at Oberndorf am Neckar in May 1918. The first of these off the production lines were issued to specially raised anti-tank detachments. The idea of using heavy calibre and high velocity rifles as anti-tank weapons originated in Germany. In June 1917, the German Army faced the menace of the Mark IV tank, and found that the armour-piercing 7.92 mm K bullet was no longer effective.

Operation
The rifle was a single shot bolt action rifle using the Mauser action, with rounds manually loaded into the chamber. The weapon had a pistol grip, bipod but no method of reducing the recoil such as a soft buttpad or muzzle brake. The iron sights were a front blade and tangent rear, graduated in 100 meter increments from 100 to 500 meters. The rifle was operated by a two-man crew of a gunner and ammunition bearer, who were both trained to fire the weapon.

Cartridge
The armour piercing hardened steel cored 13.2 x 92mm (.525-inch) semi-rimmed cartridge, often simply called "13 mm", was originally planned for a new, heavy Maxim MG.18 water-cooled machine gun, the Tank und Flieger (TuF) meaning for use against "tank and aircraft", which was under development and to be fielded in 1919. The rounds weighed 51.5 g (795 gn) with an initial velocity of 785 m/s. At 100 m an armour plate 22 mm thick could be pierced.

Survivors
The anti-tank rifle can be found in several museums: Patton Museum, Fort Knox, In Flanders Fields Museum, Ypres, The Imperial War Museum, King's Own Royal Border Regiment and 22nd Cheshire Regiment museums in the United Kingdom, the Army museum at the Invalides, Paris, the Army Museum Bandiana in the City of Wodonga, Australia, Queensland Museum, Brisbane, Australia. The Royal Armouries museum in Leeds (UK), Norwich Castle Museum,the National World War One Museum in Kansas City, MO and others. There is at least one in private ownership in the UK. And there is one that was a de-milled version and it was retooled to use the current .50 caliber round available to civilians by using a special replacement barrel. It is also on display in the lobby of the McGill club in Montreal, being the gift made in 1919 by a Canadian general. Another can be found on display in the Officers and Non-Commissioned Officers (ONCO) Mess of the South Alberta Light Horse in Medicine Hat, Alberta.