The theory of recoil is based on **Newton’s third law of motion**. Newton’s third law of motion states there is an equal and opposite reaction for each action.

**The recoil of a gun is defined as the rearward or the backward motion of the gun in reaction to the forwarding motion imparted to the projectile and propellant gases. The recoil caused by the gun balances the forward momentum of the projectile and exhaust gases.**

The various concepts involved in the theory of recoil, including the factors affecting the recoil, are discussed in the article.

The theory of recoil, in technical terms, is the result of the conservation of momentum. The forward momentum gained by the projectile and gases is accompanied by an identical gain in the rearward momentum of the gun. The speed of the recoil system of a gun is low compared to the muzzle velocity.

## Factors affecting the recoil include the following:

- The forward motion of the ejecta which forms around 50%
- The outrushing gases which contribute to around 10%
- The muzzle blast that contributes to around 40%.
*Muzzle blast*is the noise generated by the turbulent mixing of gases near the muzzle that travels both away from the muzzle and towards it.

### Recoil velocity and recoil energy are two major concepts of the theory of recoil

**Recoil velocity**: It is defined as the backward velocity that is experienced by a shooter when one fires a bullet. Due to this velocity, the shooter experiences a backward jerk.

The formula gives recoil velocity of a gun with mass M is given by the formula

**MV =m1v1**

Where **M** is the mass of the gun. **V** is the recoil velocity,

**m1** is the mass of the projectile, and **v1** is the velocity of the projectile.

The recoil velocity of a gun can also be calculated using the recoil velocity due to gas. The formula is

**Vg =m2v2/M**

where **Vg** is the velocity due to the gases, **m2** is the mass of the powder charge, **v2** stands for the average velocity of gases, and **M** is the mass of the gases.

**Recoil energy**: Another important concept of the theory of recoil is recoil energy.*Recoil energy*is defined as the measured kinetic energy imparted to the shooter of the firearm when one fires the gun. It is usually expressed in terms of joules.

Recoil energy has the same magnitude as the bullet‘s kinetic energy. It is the energy that gives push on the shoulder and muzzle lift the handgun.

**Conclusion**

When one fires the gun, the backward thrust felt by shooter is referred to as the theory of recoil. Recoil produced by a gun can be minimized by the use of Muzzle brakes and recoil compensators.

.These are devices fitted on the gun’s muzzle that redirect the propellant gas that counters both recoil of the gun and the unwanted rising of the barrel due to rapid firing. A recoil booster is also attached to the firearm’s muzzle to increase the rate of fire in short recoiling weapons.