I have a 15# tumbler, like this Model B http://www.thumlerstumbler.com/rotary.html .The same barrel. I given a barrel and I made the rest. It wasn't hard, my wife had an ancient Loratone rock tumbler that I had rebuilt, so I just copied the ratio. My problem is my brass is in lots of 20 a lot of the time. Any hints on running small batches in larger tumbler ?