Don't know about that gun, but I have a T/C NewEnglander 12ga with choke tubes. I have tried several different round ball loads and all have been very disappointing for accuracy, and that's with a peep sight on the tang!
My old .62 smoothbore flintlock did much better with a round ball - out to about 30 - 35 yards, then accuracy is very erratic with a round ball and no spin on it.
The smoothbore is a lot of fun with shot for small game hunting, though!