When I get home from the range I usually have a big bag of mixed dirty brass. I throw it into a bucket of hot water with a capful of Simple Green (~5% solution) and let it soak for fifteen or twenty minutes. Then I rinse it and let dry for a day or two. This removes all the crud and most of the burnt powder, saving my media. I eventually tumble it in Desert Blend walnut media with a capful of 50% NuFinish and 50% Mineral Spirits for three hours.
After loading I tumble again for 30 minutes. It sparkles.
