Blue Book of Gun values, Colt
Take your pick. Various Colt serial numbers and dates.cut & paste http://www.proofhouse.com/colt/index.html
all colt SAA pistols have serial numbers. If the serial number was filed off then the gun is Illegal to have, and without serial can't tell when made...............
Where did you get that gun?
1924
If you want to know when it was made, you need to call Colt.
For Colt, go to proofhouse.com
The Colt 1917 45 ACP revolver serial is most likely located under the barrel or beneath the grips on the gun. This gun was manufactured in the early to mid 1900s for military use. The gun's serial number gives you an idea of when exactly the gun was made.
about 1973
For Colt series,try www.proofhouse.com
Look on the butt or the frame.
You will have to call Colt to find out.