Rikkn
US Veteran
Pick up a huge variety of stuff today ! 35 handguns. Several vintage S&W's . Here's one I have never seen before. A note in the box identified it as a top brake single shot prototype target pistol.
I don't think what you found is what you think it is. Easy way to find out is a S&W Letter. Or you could join the S&W Collectors Association and try getting a "born on" date from Roy.
Using my clairvoyance, I can see the serial number of your engraved Model 3 American - 20029??