Thanks for all the responses! It seems I'm on the right track as far as my walnut media goes, approx 1000 rounds till it gets sent to the can, for lack of being able to clean efficiently. I love the idea of the STM and hope one day to own the proper equipment.
Common sense tells me that trying to clean the brass in a Sonic cleaner prior to tumbling would make a lot of difference in the life of my media, and is a great idea! Never thought of that one.
Curious to see if anyone else has other methods of making their media last longer? Or become more effective.