Reb, the gun has the "look" of Colton and Union guns made in Toledo, Ohio. I guess we call your gun a boxlock with sideplates. As I see it, the sideplates on your gun are not used in the gun's operation. The Colton Model 1902 has an odd shaped sideplate that might remind one of yours, but it is not the same. The Colton has a sidelock mechanism, with coil springs, attached to the sideplate. The general look and finish on your gun is similar to the Colton, including , shall we say, lack of refinement. Triggers and trigger guards are good examples of this.
It is possible your gun was a prototype boxlock that never got off of the ground.
