I have a Thumblers Tumbler, it has a 15 pound load limit. 5 pounds of SS pins, 2 pounds of brass and a gallon of hot soapy water (+1/4 teaspoon of Lem-a-shine) is the recommend load. that leave about a quart of air space, which is needed for bubbles to have some place to go!

A chart came with my kit from STM that says 2 pounds of brass is: 50-75 300 Win Mag, 80-120 308 Win, 70-77 45-70, 37-41 338 Lapua, 25-40 50 BMG, 230 9mm, 150-180 223 Rem, 160-180 45ACP.

The tumblers can hold much more brass and use less water, but the weight strain on the motor is what will determine the motor's life! I know a Thumbler's owner that has 24 years on his, I have 6 years on mine. None of my vibrator brass cleaners lasted more than 3!

You can adjust the ratios to match the RCBS capacity, but I would remain on the light side, say 25 pounds.

Ivan