[Johnny Peppers]

Your pistol was serial numbered in the military style of stamping the last two digits of the serial number on the small parts in a conspicious place. The S/42 is the military code for Mauser as was 42 and byf in later years, and the 1937 is the year of manufacture. Your sideplate should also have a 74 stamped inside in addition to the 38 stamped outside.