The TC.56 was made expressly for the Massachussetts smoothbore season when BP deer hunting was first re-introduced there in the 70's. TCbuilt it using their .54 Renegade barrel blanks, and they intended for it to be a smooth rifle.
It canshootwith rifle like accuracy at 50yards witha tightly patched .550 ball, a .015 patch and90 - 100 grains of Pyrodex. Starting that combo could be assistedby tapping with a mallet, and wiping between shots is important.
A looser combination using a .530 or .535 ballwill shoot with acceptable accuracy but justwon't group as tight.
When hunting, one idea might be to first load with the tight combination and then toreload with the looser combination for more quickness and ease.
And aslightly thicker patch may also shoot a little bit better if using the looser balls.
Heavy turkey loadscan bedeveloped for it that are effective out to about 25 yards or so.

Track of the Wolf sells cast .550 balls:

http://www.trackofthewolf.com/(S(rnx12eni5lzure55fefvlo45))/categories/tableList.aspx?catId=2&subId=25&styleId=58 &PageSize=25&Page=3