Dies are the heart of the reloading process. Engineered to the highest standards and manufactured to the tightest tolerances, they're constructed from case-hardened steel, precision-drilled, reamed, polished and hand-inspected twice before leaving the factory. RCBS dies can be counted on to produce consistent and reliable results for shooters who demand reloads equal to the quality of their firearm. Includes plastic storage box and loading data table. Full-length sizer dies for bottleneck cases have vents to prevent case damage from trapped air and excessive lubricants. Seater dies have a built-in roll or taper crimper. Large, easy-to-adjust hex-lock rings. Makes reloading easier for AR style or semi-auto shooters. A must for the progressive reloader. This set contains a small-base resizing die and a new taper-crimp bullet seating die. The taper crimp is more forgiving when various case lengths are loaded at the same time, especially in a progressive press.