I use a vibrating type tumbler with straight walnut or corn cob media, no additives espicially not the lyman stuff that has alot of red stuff (jewlers rouge?) in it. I have found lots of residue from it inside my cases. I brush out my cases before loading them to get rid of abrasive dust.
Is this much of a concern for any one else?
I though about not polishing my brass at all, but being a Marine, I can't abide dull brass and I am attracted to brite shiny things!
Roy