I think it is a J&W Tolley "Ubique".
There is another thread in the Paradox and bore gun section with a copy of an original ad stating they are four pounds lighter than a fully rifled gun.

http://forums.nitroexpress.com/showflat.php?Cat=0&Number=108603&an=0&page=2#Post108603
-scroll down a ways to tinker's post-

It also states that they will make them on their "smooth bore Ubique" principle.
This may actually be an unaltered gun...