I have used corn cob media for my tumbler for several years with complete satisfaction. While I was out West, I bought some walnut while in a Sportsman's Warehouse and I just go to say, stick with the corn cob media! The walnut is waaaay too dusty for my taste. The corn cob media seems to get the brass much cleaner too, or do you guys that use the walnut know something that I don't? I have put brass polish in it, and that didn't seem to help things either.