I have one that i found a a gun show back in the 80's. Bought it very cheap, no one knew anything about it. Have never fired it. It may have been assembled from a kit, but i'm not sure. There are sights on both barrels, 1 barrel has TC type sights on it, the other something smaller. Trigger pull is awful. The swivel part operates smoothly, there is only one lock and hammer/trigger assembly that has to be dealt with. I think it is a 44/45 caliber, haven't measured.
If you need more info measurements, etc PM me.
One of these days i'm going to have to work on it and try it out. Full time job and two part time jobs takes up a lot of my time....
rayb