plumber wrote: Perhaps I might be better off building a small bin and sticking with bagged coal.
The drum will hold 400 pound of coal and if you get bulk it's almost a necessity without a sloped floor. It's the same issue with sloped floor, without the drum you need a ton of coal on it to get a few hundred pound that is usable. With the drum it will use most of it. Most people put a hole through the side of the drum but if you put a hole in the bottom and set it on blocks above the worm you can get all 400+ pounds.
I wouldn't be dealing with bags for either cost or convenience.