Re: I know nothing....
With my 300 I just use one brand of brass now. With my 22-250 I use several (pmc, Win, rem, Frontier, fed). I try to keep it sepperated by brand and when I am getting real fussy with load development I sort it by weight as well to try to keep the internal case volume as close as possible when doing my load tweeking (narrow the variables so to speak).
The internal dimensions will affect the pressure formed in your case so it would be foolish to assume that a very hot load in brand x brass would shoot similarly to brand y brass.
I used to re-load but now I "hand-load".
-- Well, at least I try