As you are free to read elsewhere, complete with detail photos, what you describe is a virtual impossibility. My guess is that we have another victim of the " Wass school of gunsmithing". go figure.
By the way, those weights and the fast over mass thinking started way back with Billy Myers trying to convince Alan what he needed for reliable ignition. They came alive when Gordon Eck started to work on a few and almost every one that occaisionally show up in the winners circle has been changed accordingly. It has greatly improved ignition consistancy.
Yeah, you're probably right, what do all those dumb gunsmiths know? Besides I'm still working on the mysterious elongating firing pin?
It is possible to ding a chamber with an extractor cut barrel and a pin that DOES NOT protrude past the end of the bolt. I had a barrel on my Lonestar that was not coned and the pin is .005 behind the end of the bolt. It has a jewell trigger in it and shoots pretty good. I loaned the gun to a shooter at one of our tactical matches. He had never shot a light trigger before so I told him to try it a dozen times in it with a spent case in there just for good measure. Long story short, at the end of this learning, I notice the cases not coming out good. Looking at them shows a dimple. I inspect the barrel and there it is. I ended up ironing it out and then running my reamer in to take anything else out. Its an extreme case, but it happened. Although the brass is softer, it still provided enough toughness to transfer the hit and ding the barrel after thinning out after a few hits.
Sure, I can see how beating multiple times on a spent case can do that, however, friend Peter indicates his happened through normal firing. I'd wager plenty that there's far more to this tale than published.