Well done - years ago, I experimented with various slugs (moulds) in a faster twist .50 from Les Bauska, Kalispel, MT.

Even the TC maxiball shot very accurately, however it's shape is a negative for hunting purposes, as front end tends to collapse (become smaller in diameter) into the massive grease groove, rather than expanding as desired.

The trouble with most modern bullet designs is the lack of sufficient lube capacity to keep fouling soft. I-too used Oxyoke felt or wool wads, that were lubed. They helped a lot and allowed multiple shots without having to wipe the bore. I am referring to the use of real black powder, not the extremely corrosive, perchlorate packed phony powders.

The 'best' bullet I found, was a hollow based design by Lyman, now obsolete, which was adjustable, casting bullets from 350gr. to over 500gr. The best weights were in the 400 to 450gr. weight.

Please keep us posted on your experimenting, Tom.