I sort by headstamp when accuracy matters. I'm a brass whore too, but I keep the various makes separate, so that when I load a batch, I know that at least the brass dimensions are similar. Can't imagine chasing accuracy with mixed headstamps, particularly at 400. It's fairly easy to have enough of each headstamp on hand to load up a few hundred of one or the other, and your chances of shot-to-shot variation go way down.
Who said I was chasing accuracy?
