The Mauser 13.2mm TuF (German: Tank und Flieger; lit. "Tank and Aircraft", known also as 13.2×92SR), was a major step in the development of anti-tank cartridges, being the first cartridge designed for the sole purpose of destroying armored targets.
The cartridge was used in the Mauser 1918 T-Gewehr rifle. Its use was also planned in a new machine gun scheduled for deployment in 1919, the MG 18 TuF.
The 13.2 mm Tuf was design to counter British tanks which made their appearance during late World War I. Since a tank's path was difficult to determine prior to its deployment near the front, land mines were difficult to employ as a deterrent to their forward passage. Thus, another means of combating these early armored vehicles needed to be found. Since early plate armor was relatively thin due to the need to reduce vehicle weight for low powered drive trains to propel the unit, large bore rifles could be used to harass and occasionally injure tank crews. A bullet penetrating the first armor plate would lose most of its energy and be unable to penetrate the vehicle's rear. This meant that the round would ricochet inside the tank's crew compartment, hacking its way through enemy personnel and disabling the tank's combat effectiveness.
The development of the .50 BMG round is sometimes confused with the German 13.2 mm TuF, which was developed by Germany for an anti-tank rifle to combat British tanks during WWI. However, the development of the U.S. .50 caliber round was started before this later German project was completed or even known to the Allied countries. When word of the German anti-tank round spread, there was some debate as to whether it should be copied and used as a base for the new machine gun cartridge. However, after some analysis the German ammunition was ruled out, both because performance was inferior to the modified Springfield .30-06 round and because it was a semi-rimmed cartridge, making it sub-optimal for an automatic weapon. The round's dimensions and ballistic traits are totally different. Instead, the M2HB Browning with its .50 caliber armor-piercing cartridges went on to function as an anti-aircraft and anti-vehicular machine gun, with a capability of completely perforating 0.875" (22.2 mm) of face-hardened armor steel plate at 100 yards (91 m), and 0.75" (19 mm) at 547 yards (500 m).