RCBS 9805 Expander-Decapping Unit .243 Win/6mm

The RCBS 9805 Expander-Decapping Unit is a factory replacement assembly designed to drop into RCBS sizing dies chambered for the .243 Winchester / 6mm family of bottleneck rifle cartridges. It combines three precision components into a single installed unit: an expander rod, an expander ball, and a decapping pin.

When mounted inside a compatible RCBS full-length sizing die, the 9805 performs two of the most important case-prep steps in one downstroke. The decapping pin pushes the spent primer out of the primer pocket, while the expander ball rides up into the case mouth and gently bells it back to round so a new bullet can be seated without crushing the brass. It is the consumable wear item that keeps a bottleneck sizing die doing its job, and a bent decapping pin or oversized ball is one of the most common reasons a die starts leaving primers stuck in the case or folding the case mouth in.

This specific 9805 unit is sized for 6mm bottleneck cases and is confirmed to fit the .243 Winchester, .240 Weatherby Magnum, .243 WSSM, and 6mm Remington (.244). It is intended as a replacement part for hand loaders already running an RCBS sizing die in this caliber, not as a stand-alone die, press accessory, or complete reloading tool.

Precision machined for concentricity and finished in Gray, the 9805 is built from metal for long service life under repeated press cycles. Sold as a single replacement unit (quantity 1).