I'll have to go with Swampman on this I've never had a problem shooting round balls from barrels with fast twist rates.
Accuracy with a fast twist rate is better with conical bullets , but I have never noticed any loss of accuracy between a round ball fire from a fast twist as opposed to a slow rate of twist. The two may not like the same load combination ( patch, ball, and powder charge ) , but that is all about load development.
The main advantage to slow twist rates is they are easier to load and clean.
Pat