I use the pet store ground walnut bedding. It's fine enough that it doesn't clog the flash holes. I add a drop or two of liquid auto wax and haven't found the dust to be a real issue. It helps leave a "slick" finish on the cases. Used corncob for a while, but it did tend to clog the holes. Haven't used rice, so can't comment on that. I tumble my cases to "clean" them, a high-gloss shine is not my intention.