It's hard to say, because S&W manufactured these until the late 1920s, but they were cataloged and sold from factory inventory until 1940 (gun sales were very slow during the Depression). One clue would be the grip type. If the grips are checkered wood with no S&W medallions, it would have shipped in the 1920s (most probably mid-1920s). If they have small silver S&W medallions, then it would have shipped in the 1930s. There were about 144,000 of these made, so yours is toward the tail end of production. Does it have a square or round butt?