I stopped at the china depot (harbor freight) and picked up walnut shells. This is listed for blasting and tumbler
Yep, same stuff I've been using for several years. It doesn't pack into the brass and you don't have to pick it out of flash holes. If for some reason I can't find the blast media, I get lizard litter at the pet store. It's the same stuff and buying it locally is cheaper than buying special brass media.