eli5: How does a gun compensator work?


How does adding a compensator at the end of the gun reduce recoil?

In: 2

The recoil is going straight back from the barrel. However in order to get the shooters eye in line with the sights the stock goes bellow the line of the barrel. So the recoil is not in line with the support of the shoulder and is therefore rotating the gun upwards. Even if the stock were in line with the barrel the recoil from the gun would also bend your back, hips and even push you off your feet.

The compensator redirects some of the gasses from combustion upwards. This jet will then push the mussel of the barrel down countering the rotating forces of the recoil. You still have the regular linear forces pushing you back but at least the barrel stay on target for the next shot.

– Depending on the mechanical system of the gun the recoil pushes the gun back and/or the gun barrel upwards.

– The exploding gases propelling the bullet forward exit the barrel at the front (producing the sonic boom and the muzzle flash).

– Compensator systems use muzzle brakes to direct a part of these gases into the counter direction. The gun pushes back, the recoil compensators pushes forward, with that reducing the end recoil.


On an uncompensated gun, the gas leaves the muzzle uncontrolled and while it mostly pushes straight back, it also goes in every direction. When you put a compensator on the barrel, it directs the flow of those gases in a direction you want to push the barrel in a direction you want it to go.

Two ways:

1. It adds a bit more weight to the front of the barrel (doesn’t help much, but it does have a minor effect), and
2. it directs the gas escaping from the barrel upwards, countering the some of the force of the recoil.

To expand (heh) on number 2, there’s a *lot* of gas that is created by the burning powder. This rapidly expanding gas is what pushes the bullet down the barrel in the first place. When that gas gets to the end of the barrel, it continues to expand in all directions (this rapidly expanding gas is what makes a majority of the sound from a gunshot). A compensator is a device that attaches to the end of the barrel and is solid on the bottom, but has vents cut in the top and sometimes the sides, depending on the model. So when the gas exits the barrel, some of it escapes out of the top of the compensator before it can go in any other direction. This results in more “thrust” in one direction, which cancels a portion of the force of the recoil.

You are possibly mixing up some terminology.

A compensator helps with the reduction of muzzle rise. Muzzle rise is the tendency of a weapons muzzle to rise upwards when fired. This is because most hand-held weapons are braced below the midline of the barrel.

Recoil is the energy imparted into the weapon by firing. The direction of movement is directly opposite of the direction of the projectile. A muzzle brake helps reduce recoil.

Muzzle brakes and compensators operate on the same basic principle. They direct the flow of gas from the muzzle to create a force on the weapon being fired (similar to how rockets direct a flow of gas to push the rocket forward). A compensator will direct the gas upwards. This results in a downwards force on the muzzle that helps arrest muzzle rise. A muzzle brake redirects gas backwards toward the rear of the weapon (its also angles out to the sides to not blast the shooter with hot gas). This imparts a force on the weapon opposite of recoil.