RCBS Full-Length Die Sets are precision-machined from proprietary die steel to exacting tolerances, then carefully finished to provide the hand-loader with the best dies on the market. Each set includes a Full-Length Sizing Die and a Bullet Seating Die, specifically designed for reloading bottleneck cases. The Full-Length Sizing Die features an Expander-Decapping Unit, sizing the case to SAAMI minimum cartridge dimensions, while de-priming and expanding the neck to properly accept the bullet. Vents are incorporated to prevent damage caused by trapped air or excessive lubricant. The headspace is held to precise tolerances to avoid altering the case body length during full-length sizing. The Seater Die includes a built-in roll crimper to securely crimp the bullet while seating it, ensuring consistent and reliable ammunition.