I am guessing a muzzle break would harm its sales to PH's...

just copied this off of an article on wikipedia..

This cartridge was intended to be the largest bullet that was able to fit in the CZ-550,[1] and was designed specifically for the purpose of elephant hunting. The CZ-550 is able to fit 2 cartridges, with slight alterations. With solid brass bullets, the .600 overkill is able to penetrate 6 feet (1.8 m) into solid oak.

6 FT of solid oak is some serious penetration...

Ripp