Sinclair Carbide Neck Expander Mandrels are precision ground from solid carbide for closer tolerances and increased lubricity, resisting galling and scratching.
The mandrels are designed to be used with Sinclair's Expander Die and Neck Turning Tools, sized .001" smaller than bullet diameter for optimal neck tension and concentricity.
Specifically for 8mm, 32 Caliber cartridges, the expander mandrel has a diameter of 0.322 inches, tailored for years of experimentation by hand loaders.