Just put a muzzle brake on my 300wsm A-Bolt hunter ... I got the 1/2-inch standard pitch thread. Not enough barrel to chop to get to 5/8, says my gunsmith.
There's another thread around about a 1/2-inch thread being not recommended for mounting a can b/c the threaded portion of the barrel is a weak point in case of a drop and the leverage between the can and the rest of the rifle can break the barrel there.
Also, get a calibrated rod to check alignment before shooting. Enjoy.