Our caliber specific expander mandrels are available in .0005” increments in calibers 17 to 338 and will range from .001” above bullet diameter to at least .003” below bullet diameter depending on caliber. This will allow the reloader to find proper neck tension to fine-tune their loads. The oversized expanders will also help straighten necks prior to sizing to improve concentricity. We recommend our Moly Dry Neck Lube for use with our expander mandrels