Welcome to the forum. That's certainly interesting.

I can tell you at a glance that the gun is a 1930s era K-frame revolver, but then things get uncertain. During the 1930s S&W produced a model called the K-22 Outdoorsman, a .22 LR K-frame revolver with adjustable sights and a frame-mounted firing pin. Your gun has fixed sights and a hammer-mounted firing pin. The US Coast Guard ordered some fixed-sight K-22s in 1935 for use as training weapons, but they are rare and I can't imagine they would have firing pins on the hammers. I have never seen one.

Does your gun have any evidence of gunsmith modifications? For example, could it be a .38 whose barrel and chambers were lined to convert it to a .22? I guess there would also have to be modifications to the firing pin and frame channel to make it strike the rim of a .22 case instead of the center. Also, the front sight on your gun has been heavily modified to work with the lighter .22 round. If this is a conversion from a .38, I think this gun would have shot way low with the original half-found front sight.

After WWII S&W made a short-action fixed-sight .22 revolver on the K-frame called the Post Office Model (eventually called the Model 45), but yours is a long action revolver from before the war.

Can you share a serial number, or at least the first three or four digits? If this gun has all original parts, the same number should be found on the flat underside of the barrel, the rear face of the cylinder, the underside of the ejector star and the rear-facing surface of the yoke; it might be tough to read those last two without taking the yoke and cylinder off the gun.

Definitely an interesting specimen.

EDITED TO ADD: I see Allen is thinking along the same lines that I am.

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David Wilson