The optimum rate of twist is dependent upon projectile length...A longer projectile needs a faster twist...

A .50 caliber inline will usually have a 1-28 inch twist...This is optimum for saboted bullets...

A conical rifle typically has a 1-48 twist...

Now, with round balls, it depends on the bore diameter...
My .40 caliber custom rifle has a 1-48 twist...
My .54 custom has a 1-72 twist...

So as a general rule, a round ball gun has a slower twist...

The other variable is the depth of rifling...A custom made flintlock with a round ball barrel will have cut rifling .012-.015 deep...

A factory made gun will have button rifling, a "star" or "button" is pulled through the barrel to embed the rifling, since it's not cut, it's not as deep...Button rifling usually runs about .006, or half the depth of cut rifling...This is fine for sabots or conicals, but not the best for round ball shooting...