Every single BSR I've seen has at least a broad arrow, or some other acceptance mark from whatever country it ended up going to; this one is clean of all marks other than the ones I mentioned. I would not be surprised if this one could very well have taken a little detour somewhere along the way...
It's been a while, but standard plain walnut stocks, United States Property stamp, Inspector's mark ( I believe it was GHD, again, don't have it in front of me), flaming bomb.
My "go to" is Precision Bluing in North Carolina; they have done more than a few, including a pre model 14 (single action variant), that someone left outside in a tote for a few years, so say it was rusted and pitted would be an understatement.
Also, if you pull the stocks, you will probably see a 3 or 4 digit number, identifying the month and year, if reblued; these and other stampings are mentioned in the Standard Catalog of Smith & Wesson.
True, this is definitely not a parts swap moment, and that is not what I was implying. I would have already had other gunsmiths on the phone with this...at the minimum, I would be going through Kuhnhausen's shop manual and be mic'ing absolutely everything on this. But if this is to be saved...
If you feel like repairing her, I have some S&W .38 cylinders and yokes...maybe, just maybe, even a barrel...the cylinder and yokes still in the white, never mounted. if you want, you can shoot me an email at [email protected]