If the gun has not been over in the States until 30 years ago you might consider this. There was a period in the Birmingham trade when one or two workshops like Bailon's who had hundreds of guns in at a time ,stamped a reference number on guns. I am not saying that Bailon's did ,I use them as an example.This practice went on for a while until complaints from customers stopped it.
The numbers would be a reference to a register and have no other significance.
There were also times when guns were commanded by the Home Guard during WW2 that were also marked for identification and I have seen numbers stamped to indicate ownership by Estates and state organisations such as the Forestry Commision.
