WB
The .401 Herters needs 1.27” or shorter cases
Friday, April 15, 2022, 13:18

The reformed .41 mag brass I use ends up being 1.29-1.33 etc. it won’t fully chamber till I trim cases to 1.27. That’s two hundredths ahead of a 10mm Magnum at 1.25, so close enough to use starter loads and like Gary said work up. The 10mm Auto loads are even more conservative.

My .41 mag. to .401 Herters brass need a few thousandths turned off the external web area of the case. A fun trick I figured a way. It’s the part that the shell holder hides and you can’t size a solid web anyway, it won’t go. That Smith 610 dimension must be more generous than the old Herters. The OD of a 10mm, .40, 10mm Mag., .4O1 Herters case are all nominally 0.429”. I tried some rimmed 10mm autos in my custom GP100 but the rims got into the pawl gears and thickness was an issue against the recoil shield. I made (6) cases that worked! Lol