This neck expander plug is .410" diameter, for loading lead .410" sized bullets, as a perfect fit without deformation, in .40-65 WCF, .40-60 Marlin, .40-63 Everlasting, .40-70 Ballard, .40-70 Sharps Staight, .40-70 Sharps Bottleneck, and similar .40 caliber cartridges.
Use this neck expander plug in our #LEE-DIE-45-EX die body, with standard 7/8-14 threads, in your reloading press. This Lee neck expander die body is also supplied in our #LEE-DIE-4570 die set for the .45-70 Government.
You will also need our #DIE-40-COMPRESSION black powder compression plug, to compress the powder and over-powder card to the correct depth, to allow hand seating your bullet, in .40 caliber cartridges.