RCBS Full-Length Die Sets are precision-crafted from proprietary die steel, designed to exacting tolerances and undergo a thorough finishing process to ensure the highest quality for hand-loaders. Each set includes a Full-Length Sizing Die and Bullet Seating Die, specifically designed for reloading bottleneck cases. The Full-Length Sizer Die features an Expander-Decapping Unit and sizes the case to SAAMI minimum cartridge dimensions, while also de-priming and expanding the neck to accept the bullet. Vents in the die prevent damage from trapped air or excessive lubricant. Headspace is maintained to tight tolerances, ensuring the case body length remains unchanged during full-length sizing. The included Seater Die features a built-in roll crimper, securely seating the bullet while simultaneously crimping it.