I have two tumblers because I shoot BP as well as smokless. The smokeless one I use corncob and maybe a little touch of Brasso and it will last along time. When it gets dirty enough to leave a little dust on the shells I replace it and take the old stuff and switch it to my BP tumbler. Add a teaspoon of ZUD or Bar Keepers Helper to it and the BP brass comes out spotless, but a tad dull.

How long either of them last is hard to tell, I just did 3K of dirty 9mm police range cases and since they are small the media looks about the same. Do that many rifle cases and things would be different.

Doug