It can be used to determine the approximate year your Ruger firearm was It is not necessarily the very first serial number shipped, but
This number should be used as a point of reference The above chart shows the approximate first serial number shipped for (Manufactured from 1972 to 1988) Calibers: 357 Mag, 38 Spl, 9mm Security-Six, Speed-Six, Police Service-Six Revolver
Ruger Security Six, Single Six, Service Six Serial Number History
