I was preparing to wash some 204 brass (I put them throught the washing machine I don't tumble) and I just for fun swabbed the inside of a non-washed case with a Q-tip. It came out clean. I tried the Q-tip on a washed case and it came out the same way. To further the experiment I took a washed and non-washed case, sprayed a Q-Tip with Carb Cleaner and swabbed the inside of each case. Again they looked the same. So if the outside of my brass is dirt free why do I need wash or tumble my cases. I am assuming the results would be the same with a tumbled case but do not know.