Round balls were typically used in bore rifles.

In a 2 1/2" 12 bore case 6 drams is about all the powder you can get in the volume.

If it was made for brass cases, it might hold more. That depends on the groove diameter of the barrels. About .750" indicates brass. Most were for paper cases and have groove diameters of .735" to .740".

If regulated for a conical you will notice a fast twist rate to the rifling. A ball gun will be slower twist - 1/4 to 1/2 turn in the entire length of barrel.

Each one is different and must be evaluated individually. These are only generalizations.

Curl