Thread: Headspace gauge/ case head separation

I'd suggest the OP search YT for Eric Cortina's item on setting FL dies.

Basically, you first dismantle the bolt and remove the striker assembly so the bolt will fall closed on its own if there is nothing in the chamber. Start with the die set long ( ie, no sizing other that neck) and slowly wind it down in say 1/16 turns until you reach a point where the bolt will -just- fall closed with the case in there. This will be minimum shoulder clearance and should eliminate the case separations.

Using this technique in my main target gun, the resultant shoulder bump was 1.5 thou measured with a gauge made from a case fired in that chamber.