Call Ryan Pierce @ Piercision Rifles and he will help you get the proper brake for your cartridge and barrel , his "Muscle" brakes are outstanding and they WORK !
don't let the low price fool you, these are top shelf brakes, I have 4 of his brakes on my 338 Norma Mag based wildcats and will be getting a few more for a couple new wildcats I'm doing next .....
http://www.piercisionrifles.com/brakes/
