Just my 2 cents. Stainless media isn't worth the hassle if you're doing large volumn. Its just a mess, plain and simple. With the right dry media you can get your brass damn near as clean and shiney without the extra hassle of water, soap, drying, blah blah blah
I bought some ammo at the gun show once that I didn't open to inspect. When I go it home there was corrosion and some rust. I think I might throw it in the tumbler and see what happens.
Ok trying to figure out if you are serious or not. The OP asked about loaded ammo so I assume you are talking about tumbling loaded ammo with stainless media and water/soap/lemishine? Have you ever pulled some down and checked to see if you got any water into the case? Or are you saying that you can tumble the loaded ammo with dry stainless media?