I own a NOS .47 caliber 30” OTR barrel that I got from Dixie many years ago. I think these were more common than most think. I believe in the time before choking ( be it jug, or tapered) became known, the best way to get a tighter pattern was to reduce the bore size. That being said, one has to remember that the shot from a small bore like this will produce a long shot column that isn’t all that good for wing shooting, but works fine for more fixed targets like turkeys, rabbits, and squirrels.
Hungry Horse