Factory Crimp Die. Incorporates a collet to apply a rifle type crimp to the case. Makes even the most difficult to crimp cartridges a delight to reload. Bullets do not need a crimp groove, as the collet is so powerful it will form one. A firm crimp improves accuracy because pressure must build to a higher level before the bullet begins to move. This higher start pressure insures a more uniform pressure curve and less velocity variation. NOTE: This die is not carbide.