Jack, most of the early American custom makers imported barrelled actions and stocked and finished them here. There are exceptions to that rule and I don't want to open that can of worms, but the proofs remove doubt that the barrels were imported. I don't think McComas made 2431 guns, so I don't think that's his serial number. I'd bet the action was also imported and that may be a patent use number. There are so many possibilities that it almost makes sense to just accept a nice gun for what it is and not get wrapped up in who made the components - It's a McComas of Baltimore.
Thanks so much for the information. Here's another photo of the action. No markings or numbers though.
