Have had the gun apart, cleaned, inspected, studied it.
The trigger mechanism is very interesting. The set trigger only fires the rifled barrel.
Cock both hammers, do not set, first pull fires the smoothbore, second the rifle.
Cock both hammers, set the trigger, first pull fires the rifle, second the smoothbore.
Cock only the shotgun, set the trigger, the trigger snaps, hammer is not dropped. Pull again, shotgun fires.
Cock only the rifle, it can be fired either with the trigger set or unset.
I'm assuming that there are no half cock notches in order to avoid fitting of flies.
The nipples need to be replaced, and a second rod made for the rifle barrel. The folding tang sight is yet to be freed up so elevation can be adjusted. Only threaded piece that didn't turn easily.
The barrels are 34 1/2" long, muzzles are .785" and .783" in diameter. This is a heavy gun.