13x92SR Mauser was developed in Germany during the 2nd half of the WW1, specifically for a new anti-tank gun, the Mauser T-Gewehr. Later on it was also used in the experimental TuF heavy machine guns, also of German design.
This powerful cartridge launched armor-piercing bullet weighting 52 gram at about 770 m/s, with muzzle energy in excess of 15 000 Joules.