Some time ago on this site, someone recommended tumbling brass in Zilla brand Lizard Litter. I looked into it and bought a bag of Zilla Desert Blend: Ground English Walnut Shells. I added a tablespoon of liquid polish and tumbled several hundred .204, .223, and .270 cases and it works like magic. The fine grit pours out of the cases easily and does not get stuck in primer pockets like the corn cob media I had been using. And I've never seen such a bright shine on brass. Just wanted to thank whoever it was for that tip!!