RCBS pioneered and developed 3-Die Sets for straight-wall rifle and pistol cases. The Carbide Sizer Die sizes the case and de-primes (the carbide sizer ring eliminates the need to lubricate). The Expander Die expands the case to the proper diameter to accept the bullet, and it imparts case mouth flare/bell for bullet feeding. The Seater Die seats the bullet and roll crimps. This 3-Die Set is the set you need if you own a revolver or a lever gun chambered in any of the popular revolver cartridges in the options above. It includes a carbide sizing die that requires no lubrication, an expander die so the case can accept the new bullet, and the important roll crimp seater die to seat and secure those bullets. Made in USA Component and Caliber Reference Table