I've started using Lyman's Tuffnut tumbling media but it leaves a very stubborn, red residue (from the polish) on cases, especially on the inside. Any ideas on how to remove it other than manual scrubbing? Washing the cases in soapy water doesn't help much.

I didn't like this media for the same reasons. I think they add way too much polishing compound. I switched to untreated walnut shells purchased from a pet store and I added little bit of jewelers rouge. You can add more until you get the effect you are looking for, then recharge with more rouge as needed. (Jewelers rouge is iron oxide - a form of rust really).

You might try buying some untreated walnut and mixing in some of your treated Lyman media to dilute it.

I use untreated walnut shells without the rouge just to give an initial clean to the cses after firing. It makes the polishing media last longer.

I also use corncob with the polishing compounds added. It works well too.

There's probably a hundred ways to clean and polish cases well. Unfortunately you and I hit upon one that didn't work for us

I got some of this media as well - I did not know any better. I got so sick and tired of the red residue, that I quickly canned the Tuffnut and used untreated media. Talk of a crummy product!
- mike