recoils

Recoils refers to the backward reaction or impulse experienced by a system when it exerts a forward force on another body. In common usage, it is most often described in firearms, where the backward motion of the weapon results from the forward momentum of the bullet and the propellant gases fired from the barrel. Recoil is a direct consequence of conservation of momentum: the total momentum before firing is zero, so the gun must move in the opposite direction to the forward momentum of the projectile and gases.

The magnitude of recoil depends on several factors. The mass and velocity of the projectile, the amount and speed of the expelled gases, and the mass and design of the firearm all influence the recoil impulse and the energy that must be absorbed by the gun. Heavier firearms generally exhibit lower recoil, while higher-velocity or heavier projectiles increase it. Different action types in firearms, such as short recoil or long recoil, distribute impulse differently and affect how recoil is perceived. Muzzle devices, stock geometry, and other design features can also alter the felt recoil.

Recoil management aims to reduce the perceptual and mechanical impact of recoil. Common approaches include adding weight or balanced mass, using recoil pads and stock shapes that improve contact with the shooter, and employing muzzle brakes, compensators, or suppressors. Some systems incorporate dedicated recoil mechanisms to absorb or redistribute energy and improve control and follow-up accuracy.

In physics and experimental contexts, recoil describes the opposite momentum imparted to a body when it exerts a force on another body. In particle physics, recoil refers to the momentum carried by recoil particles after a collision, or to the recoil of a target when struck, which can help infer unseen particles or constrain reaction kinematics.