If you have a tumbler you already have the means to clean cases. I have heard of using brad type nails(brass) rather than the normal media to clean really bad cases quicker. The brads also tend to clean into primer pockets a bit better. They can be bought from woodworker supply houses by the pound.. There is also a recipe that uses 'alum', a wine making residue into a cleaning solution but I'm afraid I don't remember the particulars. Remember, avoid the use of compounds with ammonia as it can weaken the brass in casings.
