This appears to be a prototype design for a revolver similar to the Mass Arms Co. Wesson & Leavitt and Maynard primed belt model revolvers but with a large brass frame an internal "zig-zag" style mechanism rather than a sidelock. The brass door ahead of the hammer is the beginnings of employing a Maynard primer mechanism.

Good with mottled gray and brown patina, moderate pitting, and dark aged patina and dings and scratches on the brass. The grips are also good and have some scratches and dings and a crack in the left. Mechanically needs work.