Can't help but wondering the chamber reamers used, were all similar or to CIP specs, in that they would allow the largest bullets be used, ie: .358/7?

Found this:

This would suggest if the fired case's neck is larger than .380", that it would hold/chamber a .357" bullet, no matter what the groove diameter was.
If this is the "case" then suitable reloading data could be produced.
If a fired case does not allow a bullet to enter, that diameter bullet cannot be used, unless other 'things' are done to the chamber, the case, or perhaps both.