I am glad to try to help you understand this.

Technically, yes if a case is longer than another, and bullets are seated using the same crimp groove, the case that is longer will have more internal space if you use the same load data. If one case is longer, then you would need to seat deeper in the longer one to maintain case volumn, and OAL, that is correct. But the crimp plays a roll in how you seat, so you have to take al things into consideration.

But.....as I said earlier, IF you have let cases get that much too long, you have other problems to start worrying about. Also, you would need to implement better reloading habits, as no case should gain so much length that it can effectively increase case volumn enough to affect pressure that much. Unless you are using a round for an auto, you should be using the crimp groove provided, unless you have enough experience to know how to crimp in different locations, like over the front driving band on some bullets like Lyman 358429, which is too long for the N frame .357's when crimped in the crimping groove. There again, case volumn comes into play when you change the crimp location from what is shown in the manuals.

If you are using the same bullet in both cases, then bearing surfaces will be the same, and not play a role in pressure.