For my CF rifles i keep the brass to one brand per cal. , my 223 and 218 Bee i use Win.
And for my 22-250 , 270 , 47/70 and 450 Marlin i use Rem. all of my pistol are midway brass only because i got a deal on a BUNCH of it years ago .
Yes , mixing brass can make a diffrence , more so when using max or near max loads , the case cap. will change from one brand case to another , some only slightly but it can make a diffrence .
stimpy