Expander Mandrels

Precision Ground, Solid Carbide, Available in .0005” Increments

Our solid carbide expander mandrels are made to be used in any of our Modular sizing dies with the appropriate collet. Note that the appropriate collet is often “one size larger” than the mandrel, as the precision grinding process requires we start with a larger piece of material and bring it down to size; therefore, the top part of the mandrel, what the collet interacts with, is larger.

Our Expander Mandrel is unique because it expands the necks of your brass on the “down stroke” instead of the “up stroke” of your press. Furthermore, the precision ground expanding detail is high up in the die, slightly below the cartridge’s neck/shoulder detail. The benefit is that as the cartridge is pulled out of the die, the cartridge neck transitions from the neck bushing to the expander mandrel right away. This 1). ensures a seamless transfer of the cartridge neck from the Neck Sizing Bushing to the Expander Mandrel. 2). Expanding is more consistent because the brass starts off perfectly centered in the die and is immediately expanded as the brass is drawn out of the die body. This is ideal, where expanding on the “up stroke” puts all the stress and pressure on an unsupported case/neck causing runout.