Makes a big differance as far as recoil goes, also depends on which muzzlebrake you choose. The down side is noise. Never, never, never shoot a gun with a muzzlebrake without hearing protection. My hunting partner has a muzzlebrake on his .378Wby. When we start out into the field to hunt the first thing he does is put in ear plugs, do you know how hard it is to get someones attention when they are wearing earplugs. But he knows he won't have time, or may forget to put them in if he sees something. My neighbor shot a Moose two years ago with his .338 Ultra Mag, one shot no hearing protection. He had a Muzzlebrake on his gun. One shot was all it took, he now has to wear hearing aids. Permanate hearing loss with one shot.
Now for something posiative, my wife 4'11" 105 lbs. shoots an Encore 45-70 pistol, and a .338 Win Mag. She has a Howitzer style muzzlebrake on the pistol, which absorbs 95% of the recoil. She has a differant type on the .338 that absorbs 75% of the recoil. Her .338 is about like shooting a .243. The pistol is like shooting a .22.
