I've had good results using walnut media with Frankford Arsenal Brass Polish for vibratory case tumblers. I add 2 or 3 teaspoons of the brass polish to the tumbler bowl each time I clean a batch of cases. Don't mean to sound like a commercial, but the polish does not contain ammonia or other additives that can be harmful to the brass. It also shortens the tumbling time needed to get a good shine. Works great for me.
