I have a W & C Scott pinfire ca 1863/65 which had the customer's name factory cut into the rib. It reads "Made for Benjamin D Kennedy, Louisville KY". It has a top lever built under Matthew's patent with a single underbolt. It has been identified as being a quality A. It does not have a SN which appears to be extremely unusual for a Scott. Mr Crawford did the research on it at the time Scott had a facility in Washington State, USA.
PS;
My oldest Lefever has a SSN cut into the wood underneath the forend. At least it was situated where the forend has to be removed to see it but I would have much preferred it had not been there.