The boss lets you tune the rifle to any load you choose, I've seen it first hand, it works. they are loud, but reduce recoil CONSIDERABLY. They have a fitting that screws on and eliminates the effects of the brake(it'll kick again, but wont be as loud either). So wear ear plugs AND muffs at the range, then put the "cap" on and hunt. The 300 win mag is awsome, it will be enough for ANY north american game animal.