MLeake
Goodluck with those Powerbelts in your TC Hawkins. Had to many fliers with mine. Couldn't group at all with them. Didn't matter the powder charge. Rifle just didn't like them. Don't think there was enough twist.
As for roundballs, a good deer hunting load will usually be somewhere between 80-95 grns. of Black Powder or substitute(Pyrodex, etc.) or 65-80grns. 777 with a tight fitting .490 ball with some nice .017 ticking.
If only punching paper, you can work up a much lighter load.
Have fun!