The .625 Mauser Magnum is a large calibre rifle cartridge originally designed in the 1950s, and was produced sometime in 2010 by Otto Planyavsky Munitions for the collector's market.
A diagram in 1958 by Mauser employee Steven B. Ickes was shown on the cover of #347 of the ICCA bulletin in 1989.
It is a very large caliber wildcat cartridge based on the casing of the .50 BMG heavy machine gun cartridge. It has a rebated rim. The bullet weighs 1,350 grains (87.47 grams).
As it was manufactured by OPM as a collectible, its performance figures are unknown. No rifles were ever made to be chambered in this caliber.