Muzzle brakes work best with lighter bullets at higher pressures. A .257 Weatherby has almost no recoil with a muzzle brake. A muzzleloader, however,with low pressure and heavy bullets, would likely benefit the least from one of these devices. I wouldn't waste my money - get a Benchmaster or Caldwell Lead Sled to use for bench shooting. Your son probablywon't ever feel the recoil in the field while hunting.