Friend at our range has a brake on a 243 and it's the loudest rifle I believe I've ever heard. Dan.I have shot a lot of rifles with muzzle brakes and the biggest down side is the noise . The loudest brakes I feel are the KDF's and the most quiet I shot with was the Vais brake . I also put a KDF brake on a Sako 75 Light Hunter in .338WM because it would just beat me up and still beat me up after brake installed ! Go figure ? I also think caliber makes a difference in noise . I had a long range prairie dog gun built some years ago in 6MM Ackley IMP wanted to see my hits so had a KDF brake installed , turned it into the loudest gun I have ever fired ! Had to wear ear plugs and muffs to keep my hearing ! Moral of the story is brakes work but be careful of your hearing !