Unlike the pinned/recessed models (19-4 and earlier), S&W did not publish precise annual serial number tables for the 19-5 because many letter blocks overlapped with other models (e.g., Model 10, 64, 66). However, experienced collectors use this rule of thumb:
These changes mark the 19-5 as the beginning of the "modern" Model 19 era. Serial number tracking for this variant is critical because it overlaps with S&W’s switch from serializing by assembly number to a more standardized, computer-friendly system. smith and wesson model 19-5 serial numbers