Noun
cannelure (plural cannelures)
(firearms) A ringlike groove, such as that around the cylinder of an elongated bullet for small arms to contain a lubricant, or around the rotating band of a gun projectile to lessen the resistance offered to the rifling.
Also during the stage, Black Hills wanted the bullet to be given a cannelure, which had been previously rejected for fear it would affect accuracy. Source: Internet
However, at impact velocities above roughly convert, it may yaw and then fragment at the cannelure (the crimping groove around the cylinder of the bullet). Source: Internet