The 14 inch long cylinders minus the fixed end and the plug have a internal capacity of 150 cubic inches. The outer drum houses 4 cylinders making total usable volume 600 cubic inches.  

 Conversion

 150 cubic inches = 2.46 liter

 150 cubic inches = 2.6    quarts liquid   2.23 quarts dry

 600 cubic inches = 9.84 liters

 600 cubic inches = 10.4 quarts liquid   8.9 quarts dry

Water weighs 62.4 lbs. / cubic foot

 62.4 / 1728 = .036111 cubic inches  .036111 x 150 = 5.417

 Each cylinder holds 5.4 lbs. water

Brass wieghs 534 lbs. / cubic foot

534 / 1728 = .309 lbs. / cubic inches

 4 lbs. brass cartridges = 12.945 cubic inches

 This tells us there is a lot of empty space in brass cartridges and this reveals a lot of surface area to clean.

    

 No established capacities have yet to be determined.  Our extensive testing included; stainless steel pins with water and soap solution, crushed walnut shells and ground corncob. The heaviest was the stainless steel pins and water. Typically 3 to 4 lbs. brass casings, 2 lbs. stainless steel pins, about 5 lbs. ( about 2 quarts ) water, total 11 lbs. empty cylinder 2. 2 lbs. combined total 13.5 lbs.  4 cylinders with similar loads; 54 lbs.

 It worked fine.

When loading the cylinders with differing media special  attention should be paid to weight. Dry loaded cylinders are lighter than wet loaded cylinders.  Balance in the drum depends even weight distribution, slight variation is OK however extreme variation will cause excess vibration. Best practices include keeping the cylinders as even as possible.