OS OK -
The instructions with my Thumlers model B indicated that the drum has a 15 pound capacity. Here's how I load it:
5 pounds of SS pins
5 pounds of brass, and
5 pounds or so of water. This will cover the brass by an inch or two.
To this I add 1 ounce of wash and wax and 1/4 TSP of Lemi-Shine. That's it. Tumble for 3 or 4 hours depending on how tarnished the brass was.
23 pounds is way over the weight I've ever used in the model B drum, although I've experimented with a couple pounds over 15 and that still worked fine.
Bayou52