I looked into these when I got my KAC rifle. Not many 3/4 mounts out there. Don't wanna tell you the wrong info, I'd call Surefire and ask them. It's what I usually do. I recall one being rated for .300mag and another not. One had better suppression levels than the other. None were top notch in performance, FWIW, and I couldn't see how they warrant the price they sell for.
I opted for the KAC can because it suppresses just as well, has a solid mount and was just easier. It's costly, but if you have a KAC rifle already, it's not too bad. They have some of the best mounts and locking systems on the market --can indexes TDC to the brake and ratchets on using ball bearings that lock into the mount. SOLID.
If you want a hard use can, I'd recommend the Saker or the KAC from experience. Saker is probably the better all around can though. Good luck!