Sinclair stainless steel neck turning and expander mandrels for 17 through 50 caliber cartridges are turned from high grade stainless steel on precision turning centers. Turning mandrels are sized .002 inch under bullet diameter and expander mandrels are .001 inch under bullet diameter. The shape and surface of all mandrels is the result of years of experimenting by many expert handloaders. Our Carbide turning mandrels are precision ground from solid carbdie stock, which yields even closer tolerances. All carbide mandrels are ground to.002 inch under bullet diameter. Adjustments on our NT-4000 turning tool will be more consistent with carbide mandrels due to the tighter tolerances of the mandrels. large caliber (35 to 50 caliber) mandrels fit only the Large Caliber Expander Expander Body and NT-5000 Turning Tool.