I own and shoot two different 16b SxS bore rifles, both of them sport fully rifled barrels and express sights.
I shoot roundball.
I haven't been fiddling with them lately, but the first image here is of my first day out with one of them, note the two holes on the lower left corner of the cardboard target backer.
Those are the rifle's first breaths in over a hundred years, shot at fifty yards.
The following images are from a J&W Tolley catalog.











--Tinker