Here is my guide to tumbling with SS media:
1. The most important part of your mixture in my opinion is going to be the soap you choose. Many recommend Dawn, which works excellent, but I have found Ivory soap to be as effective at cleaning and it seams to dry much faster. I also never have stains on my brass after drying when using Ivory.
2. Lemi-Shine. This is where most people become confused. How much to use? There is really no correct answer for this as the volume of water used will likely be different for the amount of brass you are tumbling at that time. LESS lemi shine is always better! I never put more than a teaspoon (likely less) in my mixture no matter the amount. Adding more lemishine only discolors your brass and doesn't add to the effectiveness of cleaning. In addition to this, warm water is excellent, HOT water not so much -- especially with lemi shine in the mix. You can bet you will have discolored brass if your water is too hot and you have added more lemi shine than needed.
3. More stainless steel media IS better. My experiences have concluded 5lbs is not enough if you are using a tumbler relative to the Frankford Arsenal. Here is why. Stainless steel pins make the tumbling action less violent and this is important so that you don't peen the mouths of your case necks. Not only do more pins prevent peening, but they also give the tumbler more opportunity to clean the brass (especially the primer pockets) effectively in a shorter amount of time.
4. Decap your brass prior to cleaning. This doesn't mean size your brass, but only punch the primer out prior to your first tumble. It is important to clean your brass before sizing and by cleaning two times (you will clean once more after sizing to remove case lube) you can be certain you gave your best effort to clean those primer pockets. Also, it is not necessary to use lemi shine for the first cleaning. The ivory soap does the job by itself.
5. Do not trim your brass prior to the second round of cleaning. I trim just prior to my final steps of loading. Wet tumbling with SS media after the brass has been chamfered can removed some of your hard work. You want to ensure your bullet has a smooth, consistent tension as it enters the case mouth.
For full disclosure, I have not ran a scientific experiment on what I have recommended, but this is what has worked best in my experiences with wet tumbling. If done correctly I feel wet tumbling can be the most effective method of cleaning your brass.
Thank you,
Mark