With the holster wear, use marks, 1950's vintage (You don't have the box, or any original S&W factory papers do you? ) about 90%+ finish on the bluing...
2" snubbies seem to go for more than the 4", and factory nickel commands a bit more too.
Don't have a blue-book, but averaging out Gunbroker results, not a lot of them have actually sold for the asking price or reserve price, but the bidding seems to peter out around $450 or so on the "hot" auctions that have more than three bids to them.
I would say $400-450 private sale. You could possibly get $500 if you've got a factory box and some papers in there. Gun store would possibly give you $375 for it. Unless there's something unique about the serial number range etc. that I'm not taking into consideration that might matter to a S&W collector.
Probably could have gotten more for it 5 years ago or more right after Safe-T-Hammer bought S&W and the lock became standard, and pre-lock S&W were commanding a premium, and the economy was better.
