[JohnKSa]

If if was the chamber, it should show up every time you pull the trigger. If it doesn't show up every time you pull the trigger, then odds are it is something with the ammo. Can you fault that line of logic?

Yes I can. If the pressure increase puts the peak pressure right at, or very near the limit for popped primers, then the pressure variations from one shot to the next that are evident in any pressure curve data could easily result in popped primers some shots (or maybe even only once out of a number of shots) but not every shot.

The comments by Sweeney regarding his experience with the mismatch strongly support the idea that the pressure rises aren't super-dramatic. He states that he doesn't usually see issues unless there is another contributing factor--such as high ambient temperatures. That sounds like exactly the scenario I laid out in the paragraph above. The mismatch pushes the pressures up near the threshold limit for problems, and if you get one round that's a little hotter than rest, or slightly oversized compared to the rest, or has the bullet seated out just a tiny bit farther than the rest, or one that hits the chamber when the barrel/chamber temp is hotter than it was for the previous rounds, that one pops a primer while the others don't.

Any pressure curve data will show that the pressure peaks can vary significantly from one shot to the next. It's quite common to see that one of the tested shots will show a significantly higher peak than the others.

The exception proofs the rule, meaning that the "similar explanation" is insufficient to explain all occurences of popped primers in ARs.

Why must there be one single explanation for all the incidents of popped primers? There's no logical reason to impose that criteria. I don't see anyone trying to claim that every popped primer in an AR is due to a chamber mismatch. There could be any number of reasons that might cause a primer to pop in any particular gun or with any particular ammo, and none those reasons would invalidate a claim that the mismatch could be one additional cause.

...having access to research data is important into weighting the relevance of conclusions drawn.

That's an issue when there's a realistic/reasonable concern that research data might be falsified, in error, or misrepresented or when there's some reason to assume that all the entities providing results might be colluding with each other to deceive. The fact that we have multiple organizations (all of which have access to, and the ability to generate, their own independent research data) providing the same warning and explanation should go a very long way to assuaging fears that the warnings are the result of one rogue organization is making stuff up, or is confused about the basics of internal ballistics.

That's unless there's some credible reason for us to assume that all the organizations are conspiring to deceive the shooting public. That's why I keep asking the question.

Or take a look at Michael Mann, still refusing to share his temperature proxy data and methodology...

SAAMI doesn't have to rely on Winchester or Hornady for pressure data. Hornady doesn't need to beg pressure data from SAAMI or Winchester. Winchester can generate their own pressure data. Your examples make it sound like we're at the mercy of a single entity who won't share their data and who is making claims that other authorities contradict.

In fact, that's not even remotely close to what's happening here. No authorities are contradicting the warnings or explanations provided, and we don't have to rely on just one organization, or one organization's conclusions.

You can say that they deserve your trust all you want, that is simply not good scientific practice.

I'm not saying that they deserve trust, I'm saying that given that we have multiple, independent sources repeating the same experiment and providing the same warning and explanation, good scientific practice suggests that some sort of credible evidence is required to call the facts into question.

That's why I keep asking what credible evidence you have (and pointing out that none has so far been provided) to call their conclusions into question.