Ted, am having fun playing with the R-14 16ga I acquired recently. I'm beginning to think it won't even need trigger tuning! The only serial number I see is F 579. Not sure what that means, if anything.
However, here's something you may find of interest: When I remove the barrels, I see two words next to the hole in which the lump fits on the water table (or what you'd call water table on a break action double). The one on the right is quite clear: Nantes, which is self-explanatory. The one on the left isn't as clear, but it looks like it might be Bruchet. Last 3 letters are definitely -het. Would that be the gun shop that sold the gun??