I think you're sort of missunderstanding the meaning of the name smooth rifle, at least as used today.
I don't believe it means a smooth styled gun or Fowler with a rifled bore, but instead a smooth bored gun with most of the typical rifle type features.
A smooth rifle will generally have an octagon/round smooth bored barrel, rifle sights, a patch box, a cheek piece, a flat toe line, a rifle type trigger guard and generally a flat faced lock as opposed to a round face lock, and rifle type carving if it has any.
I have a couple, including one that was made around Allentown and it has straight rifling.
Also don't confuse an originally made rifle, that has been bored out smooth at a latter date as a smooth rifle, because it actually isn't,,,,, although it is......
John