In post 23? I covered a sequence of events. The post was too long.
I re- read your post and I see a weak firing spring mentioned. Yup that could be a cause.
I will still stick with excessive headspace will a bunch of things. Pierced primers is not one of them.
You have to figure in another fault.. I think I also mentioned weak firing spring. Anyway, excessive headspace and pierced primers are not a matched couple, yo need something else added.
I cannot follow long posts on my phone. Too hard to go back. (Poor skill level on my part)
So I will wait until it’s possible for me to get on my computer at home
I'm not sure if we agree or disagree. Either way, I'll just give a couple of examples of things I've seen and the results/cure. First, I've seen things like cratered and flattened primers as well as ejector marks on fire forming new brass that was several thou short for the chamber. Of course ejector marks are one accepted pressure sign and most also consider flattened primers as another sign. Anyway, using the same load, both problems went away once the brass was formed and bumped for say .002 bump. The only logical explanation is the brass slams back into the bolt face, creating both the ejector mark and the flattened primer. Again, both went away once fire formed and properly bumped. This is repeatable and is worsened if there is residual lube on the case or chamber.
The way that relates to cratered or pierced primers is that the case slamming rearward into the bolt face can hit the pin hard enough for it to come out of the fp hole allowing primer brass to flow into the hole, similar to how it does with too much pin/hole clearance. The pin then bounces back and hits the primer a second time. The result is normally what looks like a classic cratered primer. But again, it didn't do this either, once sized properly, correcting excess headspace. Pierced primers are normally for a related but different reason. They are typically caused as a result of the brass primer being stretched, thinned and weakened by cratering, gone too far and the gas leak through the primer blows the pin rearward depositing that little disc left over from the primer inside the bolt. Cratered or pierced primers don't require excess headspace but they do require excess pin hole clearance. That excess clearance is typically from poor fitment of the pin to the hole but it can also be from a weak spring that backs away creating clearance...err an open hole, temporarily, before rebounding back against the primer. That bounce is how the same issue can be related to excess headspace, even with a new or good spring. I hope that's clear enough. BTW, if I didn't mention it, that "bounce" is how a weak spring can cause cratering, as it allows the pin to retract too far, leaving excess clearance around the pin...or potentially just an open hole for the brass to flow...crater.
Again, I think we agree more than we disagree and maybe it's some of both. And, I may be wrong but it can be repeated, both the problem and the cure, which is strongly indicative. Ultimately, replacing the spring every couple of years is cheap insurance against this and accuracy issues that are no fun to track down. Removing residual lube from the cases and the chamber as well as proper shoulder bump are just good reloading practices that can help prevent issues like this and if need be, having the bolt bushed for proper pin fit is a must on some actions. That fp bounce I refer to, if bad enough, can wreck a Jewel trigger too. It won't typically be that bad unless the primer pierces, letting the gas blow the firing pin likely fully rearward, then bouncing back forward having the top lever attempt to catch the cocking piece on the rebound.
