Well Im still undecided. Woods that link in your post that you are using to support the affirmative position is from the same site/people that made the video that you claim is " bull chips" If you click on the link beside the illustration it takes you to their conclusion after doing some actual testing with both reamers. The other info you posted is all based on the same assumption that the datum for measuring both chambers is exactly the same so still nothing to refute the "different datum" position taken by the makers of the video. Yes your individual chamber shows some growth from nosler brass but then mine does not so we have more conflicting evidence.
I'm not confident basing the discussion simply on the reputation of the gun builder as proof that my chamber is correct as every human makes an error at times so the simplest way I see to prove this one way or the other is to try both the original ackley and the saami spec go/no go gauges in my chamber. I have been trying to do this for some time and almost have the necessary bits together and Ill post my results as soon as I can. That will tell me if I have an original ackley as claimed by the builder , a new saami or both if there is actually no difference. Im not betting on any one outcome
Something else I was wondering about, the original ackley design was .004shorter than the parent case. If the saami is a further .014 shorter then the saami 280ai chamber would be .018 shorter than standard 280 rem brass/ factory 280rem ammo and would be quite hard to chamber and close the bolt. Has anyone seen this with a new saami chamber?
But how much of an issue is it if there is a difference? I dont see growing reports of case head seperation or any problems that could be related to excessive headsapce and this has been around for 5+ years?