I think for most of us mortals you would not be able to tell the difference if you mixed your brass or not especially at shorter distances. If you check out the
Bullseye-L Forum forum there is a lot of good information about 38 specials and accuracy. If your shooting a model 52 I understand they can be fussy. From what I understand some bulleye shooters favor specific bullets and brass when trying to get less than 10 ring accuracy for 50 yards. Personally I load them all and sort them after just because I am compulsive, not because I am good enough to tell the difference.