Recoil
The rearward force experienced when firing, equal-and-opposite to the bullet's forward momentum.
Also: kick
Recoil is Newton’s third law in action: the bullet (and gases) leaving the muzzle forward push the firearm back into the shooter’s hand or shoulder. Recoil management — through stance, grip, and firearm design (recoil springs, brakes, compensators) — is a core shooting skill, especially with high-power calibers.