A muzzle brake or recoil compensator is a device connected to the muzzle of a firearm or cannon that redirects propellant gases to counter recoil and unwanted rising of the barrel during rapid fire. They have been used in forms for rifles and pistols to help control recoil. They are used on pistols for practical pistol competitions, and are usually called compensators in this context, the interchangeable terms muzzle rise, muzzle flip, or muzzle climb refer to the tendency of a handheld firearms front end to rise after firing. Firearms with less height from the line to the barrel centerline tend to experience less muzzle rise. The muzzle rises primarily because, for most firearms, the centerline of the barrel is above the center of contact between the shooter and the grip and stock. The reactive forces from the bullet and propellant gases exiting the muzzle act directly down the centerline of the barrel. If that line of force is above the center of the points, this creates a moment or torque rotational force that makes the firearm rotate. The M1946 Sieg automatic rifle had a muzzle brake that made the rifle climb downward. Muzzle brakes are simple in concept, such as the one employed on the 90 mm M3 gun used on the M47 Patton tank and this consists of a small length of tubing mounted at right angles to the end of the barrel. Brakes most often utilize slots, vents, holes, baffles, the strategy of a muzzle brake is to redirect and control the burst of combustion gases that follows the departure of a projectile. All muzzle brake designs share a basic principle, they partially divert combustion gases at a sideways angle. The momentum of the diverted gases thus does not add to the recoil, the angle toward which the gases are directed will fundamentally affect how the brake behaves. If gases are directed upward, they exert a downward force. Construction of a brake or compensator can be as simple as a diagonal cut at the muzzle end of the barrel to direct some of the escaping gas upward. On the AKM assault rifle, the brake also angles slightly to the right to counteract the movement of the rifle under recoil. Another simple method is porting, where holes or slots are machined into the barrel near the muzzle to allow the gas to escape, more advanced designs use baffles and expansion chambers to slow escaping gases. This is the principle behind a linear compensator. Ports are often added to the chambers, producing the long
The muzzle brake of the 105mm main gun on an AMX 10 RC armoured car.
The muzzle brake of an M198 155mm howitzer venting propellant gases sideways as the howitzer is fired.