I tumble wet and dry, depending on batch size and how dirty the brass is.

For dry tumble (small lots of semi clean brass) I use corn cob and a bit of nu-finish. For wet tumble (bigger lots or very dirty brass) I don’t use any media... just brass, water, and frankford arsenal case cleaning solution. I’m not so concerned about the insides of the cases or primer pockets, I just want to get the dirt and soot off of the cases so it doesn’t end up in my dies.

With the larger frankford arsenal wet tumbler I can do a lot more brass (roughly 800 pieces of 223 in a couple hours) quicker than dry, but there is the slight mess of rinsing and drying the brass afterward.