Our neck turning tool mandrels are made from high grade stainless steel on Precision turning centers. The shape, finish, and size are the result of years of use and experimentation by many hand loaders. All of our mandrels fit both our NT-3000 and NT-1000 neck turning tools and most of our older model neck turning tools. Our neck turning tool mandrels measure approximately about .002'''''''' less than the bullet diameter for the caliber. Our expander mandrels are made .001'''''''' larger than the turning mandrels. Using an expander mandrel prior to neck turning sizes the case to fit the neck turning mandrels perfectly. This correct fit makes the turning process more precise and much easier. Any of the m Mfg: Sinclair International