[GrampaD]

Thank you, Jim, and thanks for responding. First, I was in error about two partial serial numbers on the cylinder. Actually, there is one partial number on the cylinder and same partial number on the extractor.
There does not appear to be anything other than the 5 digit serial number stamped into the bottom side of the top strap. The only thing stamped on the barrel is "H. & R. Arms Co. Worchester Mass" on the rib; no cartridge stamp on the left side of the barrel.