That looks like the Bacon & Co. gun shown in Flayderman (7E-006) but the grip is much longer, I suspect altered after-market by/for someone who wanted a better handle. It looks like the grip itself ends just below the screw and the wood continues. I can't tell much about condition from one picture, but it doesn't look bad. Only about 500 were made, c. 1847-1857.
Flayderman (9th edition) gives a value $300 Good, $875 Fine. That gun would probably fall between IF the grip alteration didn't involve some permanent change. If the frame is OK, those awful grips could be replaced by a good woodworker.
The number is probably not a serial number; at that time, serial numbers were rarely used by smaller makers. They made guns in batches of 50-100; these were fitted together by hand and the parts numbered so they could be re-assembled after final finishing. Those numbers are called "batch numbers."
Jim
