Have not made black powder since I was, oh, 12.
I have a Harbor Freight tumbler with its two rubber chambers suitable for milling BP. (I don't use the small rubber chambers for brass cleaning as I built a larger chamber from 4" PVC that holds more and is easier to seal and open.)
Some say "ball mill the BP ingredients using lead balls."
Others say, "use glass marbles."
I have a .45 Cal lead ball mold for my cap and ball Old Army. Are those large enough for effective ball milling?
Should I get a mold for a larger ball? If so, what caliber?
Will standard glass marbles work, or are they too light?