The .600-538 Mega Magnum is an Austrian big bore rifle cartridge developed in 2002 by Peter Hambrusch.
Details[]
The .600-538 Mega Magnum is based on the .600 Nitro Express case necked down to accept a .552" (14.02mm) calibre bullet weighing 722 grains (47 grams). It could achieve a muzzle velocity of 700 meters per second (2,296.59 feet per second) with a muzzle energy of 11,450 joules (8,445.0866 ft-lbs).
It is designed to be used in Hambrusch's own .600 NE-based Mega Magnum bolt actions.