No I didn't "make up my mind". I just gave you my first hand experience, based on 45 years of gunsmithing. I've seen many 06, 270, and a lot of military rifles with excess headspace that back out primers with factory loads.
I suspect those bolt face pressures would have been because of momentary head pressure & bounce back. Most likely with minimum headspace. And shooting a factory round in a AI 30/30 chamber with no locking lugs, shows very little breech pressure occurred. It should have been greater (with an unformed case), due to the case having to expand into the chamber before moving to the rear. If the pressure on the bolt face was equal to the chamber walls, it probably would have taken his thumb off.
As an infantry officer in the late 60's I taught maint & operation of the Browning 50. I could always tell when the operator hadn't set the headspace correctly by looking at the fired cases on the range next to his gun. The primers were backed out a few thousandths.
But apparently my experiences, and those of my many gun maker mentors over the years, differ from yours. That's fine too.
