Dillon Three-Die Rifle Die Sets include a sizing/ depriming die, a bullet seating die and a taper crimp die. Sizing/Depriming Die - The sizing/depriming die is full-length, to minimum tolerances, sizing cases down to function in semi- and full-automatic firearms. We strongly suggest that a headspace case gage be used to correctly adjust the size die.The depriming assembly includes a carbide expander ball for "squeak-free," effortless neck expansion. This expander ball is located in the middle of the depriming stem to take advantage of superior initial leverage for easier extraction. In the event of a stuck case, the design of the depriming assembly allows it to function as a stuck case remover.Bullet Seating Die - Our bullet seating die is internally designed to keep the bullet straight throughout the seating process. Once properly adjusted, the only measurable runout will be that which is inherent in the bullet.Taper Crimp Die - The taper crimp die is also specially configured to center both the case neck and the case body, thereby aligning the entire cartridge for a more uniform crimp. Dillon Rifle Dies are designed to meet the more rigid requirements for both accuracy and precision demanded by today's marksman. A taper crimp die is preferred for loading ammunition intended to be used in semiautomatic firearms with detachable box magazines, and in lever-action firearms with tubular magazines.