You might search on www for colt history. There will be someone with a listing of serial number ranges and dates of manufacture for those ranges. Do not however share the complete serial number. For example if the serial number is 12345 give the number as 123XX as this will protect you from a possible false claim or other scam. Additionally it used to be possible to contact the Colt Mfg Co and for a small fee, find out the dates of shipment from the Colt factory, and to what merchant the weapon was sent.