"...always size my brass to headspace on the shoulder..."
Headspace has nothing to do with the cartridge. It's a rifle manufacturing tolerance only. Brass nor cartridges have headspace.
Technically correct
Sunray. But....
Real world working headspace is a combination of the brass and the chamber. If you size the case shoulder back too far you create artificial headspace, and a dangerous situation.
The rifles chamber is cut to SAMMI specs, but the brass is supposed to be made to work in a SAMMI spec chamber. It is almost always OK when new, but if we size it down too far we create artificial headspace (too much room for the case to move forward and back in the chamber)
If we fire the round with this condition it is the same as fireing a properly sized round in a chamber with excessive headspace machined in. That chamber would be dangerous with any properly made factory ammo, because it has the type of headspace
Sunray is talking about.
In a properly headspaced SAMMI spec chamber real world headspace is controlled by the relationship between our sized brass and the chamber.
Sunray will argue that this artificial heaspace created by oversizing is called something else, and he will likely find a definition for us, but in the real world, it is headspace, created by us, which is dangerous.
Everyone who reloads recognizes the term headspace and to pick nits about what to call that "slop" in the chamber between the loaded round and the chamber only confuses things.
Bottom line is this. Do not just screw your die all the way down and hope everyone got their tolerances correct. It
might be causing heaspace in your rifle. Most of the time the manufacturers get everything right and alls well, but not always.
Take the guts out of you bolt. (spring, fireing pin) Then size your brass a little at a time until it chambers easily. Stop there. You are now sizing
your brass to fit
your chamber. This will eliminate excessive headspace, and most likely help accuracy.
Hope this is clear enough. AC
454PB - You are doing it right. If they don't believe me, they can just ask my friend The Bushmaster. He is very experienced with the 30-30.