Gary Reeder
that is what I tell folks to do with our GNR cartridges
Thursday, February 24, 2022, 11:55

Don't use the middle expander die at all. Just use a battery powered chamfering tool or the hand held tool and just barely kiss the mouth of the case. With our short necked cartridges this works perfectly keeping the rest of the case sized down. And just enough of a tiny expansion of the mouth to sit the bullet on. Maybe half a second of the chamfering tool in the mouth of the case will work fine.

Chamfering the mouth of the case until the mouth looks shiny is all you need. The bullet will sit on there and seat perfectly keeping all the tension in the case.