Hi; I have a .38 cal pistol with Patent dates from Jan '65 to Jan 1875. I tried looking the serial number up on the Smith & Wesson look up site, (Serial Search) and got the reply that "The serial number that you entered is not valid for this consumer advisory". Not sure what that means, but any help deciphering the serial number would be greatly appreciated. The serial number is located on the butt of the grip and says, 18456. If there are any gurus out there with the info, I would like to thank you in advance for the information.