Muzzle Brakes are a vented device that is fitted by a gunsmith and screwed onto the end of your rifle barrel; and is Designed to Significantly Reduce the Rifle’s RECOIL, GlassRailings.ca. In magnum calibers, recoil can cause flinching and other bad habits leading to loss of accuracy. Expanding gases from powder being ignited in the cartridge causes acceleration of the bullet through the barrel. When the bullet leaves the barrel so do the gasses; this action causes the violent reaction of the rifle forcefully slamming rearward into the shoulder causing disruption of your focus on the sight picture through the scope to the target. A miss or less than desirable shot placement can occur.
Muzzle brakes reduce recoil by diverting some of these gasses out to the sides, through the vents or ports (holes) taking away a portion of recoil. The effectiveness is dependent on the design of the brake and the caliber of the rifle. You can expect any where from 35 to 50% recoil reduction. A .375 H&H; will have the felt recoil of a .30-06; and a .338 will feel close to a .270; a 7mm Rem Mag and a .300 RUM will have the felt recoil of a .243
The muzzle brake, fitted on to the end of your rifle barrel by a qualified gunsmith, will add a few inches to the length of the barrel, with no loss of velocity of the bullet. The bullet never touches the device as it passes through; the expanding gasses still accelerate the bullet as normal. It is the deflected gasses that allow the rifle to remain considerably more still.
The sight picture of the target is easier to engage when “FLINCH” is ELIMINATED from the Mind of the Shooter. Also, when hunting alone without the aid of a “spotter” with binoculars; the quality muzzle brake will Allow the Shooter to Spot His Own Long-Range Shot, and how the animal reacts to the shot.
And yes, there is some Disadvantage to muzzle brakes. The increase of muzzle blast is substantial. They can be VERY LOUD and damaging to the ears! The risks can be diminished hearing with some permanent hearing damage. Regular earmuffs can reduce noise levels by 25dB +/- while the sound levels of a muzzle brake magnum can be as high as 128dB +/-, as loud as some pumps, meaning noise levels with earmuffs on are in excess of 100dB !!A hunter in the field shooting without protection, will experience immediate, and near complete temporary hearing loss. Hearing returns after three or four minutes, but a small portion of hearing is permanently lost each time a shot is fired.