I used a tumbler for over 25 years with every kind of media you can think of including porcelain....Do yourself a favor get a Sonic. Even if the brass is not shiny..it is clean.

If you think you need bright brass, 15 minutes in the Lyman Green treated corncob, after the sonic, will have your brass looking like jewelry ...but what ever you do stay away from the Red treated media...that rouge will do you, or your gun NO favors.