John, your gun should have a small roughly stamped date code on the bottom of the action either just in front of the trigger-guard or just behind the hinge. It is in the form of a letter (the year) and number (the month) in a circle or oval. "A" is for 1949 and each subsequent letter represents the next year. "O"and "Q" were not used. If your gun was built when you bought it in 1964, the date code would be "R". Hope that helps...Geo