rifling
ri.fling \'ri--f(*-)lin\ n 1: the act or process of making spiral grooves 2: a system of spiral grooves in the surface of the bore of a gun causing a projectile when fired to rotate about its longer axis
ri.fling \'ri--f(*-)lin\ n 1: the act or process of making spiral grooves 2: a system of spiral grooves in the surface of the bore of a gun causing a projectile when fired to rotate about its longer axis