I think it's easier in the long run to separate the brass for each rifle, and buy a set of dies for each rifle, that way when you get everything set up/finalized you don't have to adjust the dies much, if any and just reload. I do some testing during load development and find out what brand of brass a rifle "prefers", and just go from there. Sometimes the differences in brass makes a difference, sometimes not. A Rem 700 223 load prefers FC brass, while a FV12 223 load prefers LC. Makes it easy to keep 'em sorted when cleaning brass.