I've been using walnut sold as pet litter. Recently I have been accumulating a lot of brass in different conditions and adding Flitz media polisher into the mix. This works well for cleaning and polishing but it does leave an annoying dust behind.
Right now I'm recycling the media well over 10 times and running all the bulk brass with it. Eventually will dump it out and use plain walnuts without any chemicals on my spent casings which don't need much cleaning.
Proud owner of: G17 G20 G27
Currently Reloading: 380, 9mm, 38/357, 10/40, 7.62x39, 45ACP, 300 Win Mag, .223/5.56