The muzzle of a firearm is the end of the barrel from which the projectile will exit.

Precise machining of the muzzle is crucial to accuracy, because it is the last point of contact between the barrel and the projectile. If gaps exist between the muzzle and the projectile, escaping propellant gases may spread unevenly and deflect the projectile from its intended path.

The contour of a muzzle is typically designed to keep the rifling safe from damage, so it is commonly recessed or protected by a convex "crown".