HF Rubber Ball Mill Grinding -- 45-Cal Lead Balls or Glass Marbles for Black Powder?

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?

Check the Muzzle Loading section.
There is a number of threads regarding homemade BP that will probably help answer your questions.

RRR

there is an entire thread about making your own bp, including photos of various tumblers and balls.

I use 1/2 inch copper pipe pieces filled with lead, you want something that will not disintegrate over time and pollute your powder.