The most recent episode of C&Rsenal is one you will not want to miss. In it, Othais and Mae take a look at the gargantuan Mauser Tankgewehr 1918, also known as the T-Gewehr:
Now, in the video Othais notes that the 13.2x92mmR Tank und Flieger cartridge influenced a great deal of other more familiar cartridges of that type, such as the Soviet 12.7x108mm and American .50 BMG (12.7×99), which is true. However, it’s worth noting that American work on what eventually resulted in the .50 BMG began as early as April of 1918, when Winchester was contracted to design a large-caliber round for use against aircraft. After the war, when T-Gewehrs and their ammunition were dispersed around the world for examination, Frankford Arsenal did receive 13.2x92mmR ammunition, and actually redesigned the Winchester round around the German cartridge, resulting in the 12.7x96mmSR experimental round in 1919! That cartridge, though, apparently was a dead-end, as what was eventually called “.50 BMG” was a clean-sheet design derived from scaling up the .30 M1906 Ball round.
The T-Gewehr really wasn’t the most elegant solution to the problem of tanks, but it was such a simple design that development and fielding were reduced to a minimum, which was exactly what Germany needed at the time. However, the onslaught of Entente tanks was really overwhelming (though not the only factor in Germany’s loss in the war), and the T-Gewehr was still too little too late.