Sinclair Carbide Neck Expander Mandrels are made from solid carbide for improved tolerances and lubricity, reducing galling and scratching inside the necks.
Designed to be used with the Sinclair Expander Die and Neck Turning Tools, these mandrels are .001" smaller than bullet diameter for optimal neck tension and concentricity.
Specifically for .243 Caliber, 6mm with a diameter of 0.242 inches, these mandrels aid in sizing cases for neck turning or before bullet seating.