Note: An "N" prefix (N100,000) indicates a 4-screw or 3-screw model from 1970 onwards – a true 5-screw.
In 1957, S&W eliminated the uppermost sideplate screw (the one at the top rear of the sideplate). This created the configuration. However, the frames were already stamped, so you will find "transition" guns. smith and wesson 5 screw serial numbers
If your revolver has all five of these screws, you are holding a piece of pre-1957 history. The most common 5-screw models include the .38 Special Military & Police (M&P), the .357 Magnum (pre-Model 27), the .44 Special (pre-Model 24), and the .45 ACP (pre-Model 22). Note: An "N" prefix (N100,000) indicates a 4-screw