Frankly, I would stick with the Thumbler B. It's the one by far the most experiments with pin cleaning have been done with so you know the height from which it drops the cases and pins inside is acceptable. The round drums, as you read, will let the pins roll like little roller bearings and give you no drop. Too much drop will round neck mouths, bending them inward, and leave surface marks from the pin ends on the brass. Too little will leave flash holes dirty. It's a case of an empirical solution having been found and where deviating from it may produce unanticipated effects and results.
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