Assuming no letter prefix to the SN, you probably have a pre-WWII (likely early 1930s) Military and Police revolver. It is actually called the S&W Hand Ejector, Model of 1905, Military and Police, 4th Change. These are quite common, as millions were made. Value depends almost entirely upon completeness, condition , and originality, which cannot be assessed without some good pictures. Typical value at retail for one in good condition would be in the $300-400 range.