Shipment dating for 5959xx is difficult. Some I have listed having nearby SNs shipped in the early 1950s. For example, 5897xx shipped in 7/52. Only a letter will tell you more precisely. As yours has the one line "MADE IN USA" frame stamp (beginning in mid-1922) and the earlier style hammer, and also has grips of the 1920s style and the mushroom-style extractor knob which was replaced by the barrel style in the late 1920s, my guess is that yours is from the mid- to late 1920s. Are you certain the SN you provided is correct? I'd expect a SN in the mid 3xxxxx to very low 5xxxxx range for the 1920s