8 years ago I bought the kit from Thumbler's Tumblers. It contains a rotary tumbler in the 1.5 gallon size, 5 pounds of SS pins and a media (pin) separator!
I had several old 45-70's (50+) that had been stained by Black Powder for over 30 years. They had been vibratory tumbled with Corn Cob or Walnut shell, with and without cleaners, jewelers rouge, Nu-shine, & even Comet. Nothing cleaned the Black Powder fouling colors from the brass. First pass through the wet pin they shined like new. (I tumbled them for 3 hours! Since then everything else has been 1.5 to 2 hours)
The equipment I use came with instructions:
4 Quarts Hot Water
5 pounds SS pins
1 table spoon dish detergent (I use Lemon Ajax)
1/4 teaspoon Lem-a-shine (citric Acid)
2 pounds brass. (I size and deprime first, so as to clean case lube off too.)
This equals 15 pounds, the weight limit for the motor! If you want more brass per batch, buy a bigger system! (I usually am short 1 Cup of water , so the air space is a little bigger- a hint from the internet!)
After a 90 minute tumble the water is dark grey to jet black. I pour of as much water without loosing pins. Then dump everything into the separator 15 seconds of spinning and rinse and repeat brass and pins separately.
I've done handgun, rifle, and all brass shotgun cases, all come out looking new.
If you are assembling a system fro parts you find on the internet or Harbor Freight, there are many pin sizes. Measured metric or standard! you want a pin size that is in the .040" by .250" (+/- .003") size range so they don't get stuck inside the case or flash holes. I have use these on almost every cartridge from 32 ACP to 450 3 1/4 N.E., straight wall and bottle beck (Never tried 25 ACP or 17 or 20 caliber reloading.)
Try it you won't go back to the dust makers!
Ivan