Sinclair Carbide Neck Expander Mandrels are made from solid carbide for closer tolerances and increased lubricity, reducing galling and scratching inside necks.
The mandrels are designed to be .001" smaller than bullet diameter for optimal neck tension and concentricity, aiding in neck turning and bullet seating.
These mandrels are specifically made for use with the Sinclair Expander Die and all Sinclair Neck Turning Tools.