Manhattan HERO Single shot percussion pistol, cal 34

Manhattan HERO Single shot percussion pistol, cal 34   Flayderman P 131, item 5C 024

2 1/2 inch barrel, which is the shortest variation, ,no serialnumber visible , under the grips, stamped on the brass I found serial 22. brass is sharp with good markings,  A.S.T. C0 stand for ' American Standard Tool company'. Apparently approx 25000 made but I rarely see one for sale and is the fist time I have one. 

rest of metal is dark brown, shimney is usable but a bit flattened.