Fired primer damage question......

by Brian A, Wednesday, April 20, 2016, 22:29 (3077 days ago) @ Steve K

That is not what I was imagining from John's description, he was accurate with it, I was just imagining it differently.

I would very carefully inspect the bolt face for any defect, void, burr, whatever that could be having an effect on the edge of the primer. The load on the left definitely looks like there are pressure issues going on.

Another place to check would be the locking lugs on the bolt to make sure they have not been set back or distorted in some way, possibly by some former owner firing too hot loads in the rifle. It is not easy to inspect the bolt seats in the action, but if there is any distortion or damage to the bolt lugs, it can be assumed the seats are also damaged.

You said the cases were sized and checked with a micrometer, I would not recommend sizing cases based on the specifications listed in the manual, especially for an older firearm. I would size cases to fit your specific chamber by sizing them just enough for the bolt to close without being forced.

If the cases will fit into the chamber freely without being sized you may want to consider fire forming the brass by setting a bullet out far enough to engage the rifling and putting a suggested starting load, at most, under it. After firing you can measure the case to see how it compares to unfired brass to see if there is any significant difference.

Your current fired cases may not show actual headspace between bolt face and case shoulder because under pressure the case wall can expand fast enough to grip the chamber wall, not coming back fully to the bolt face until pressure in the case is low enough to not push the shoulder forward.