Try Proofhouse.com. If it's not listed there, post a detailed description.
You can find out what year your gun was made by having an expert appraise the gun. You can also find out by finding the model number and contacting the manufacturer.
Contact the maker.
this one , google, yahoo.
Proofhouse.com has sn data.
Old gun catalogs and Blue Book of Gun Values
At the gun club
You must call Colt to find out.
Blue Book of Gun Values
You will need to contact INTERPOL to find out.
Try Blue Book of Gun Values
BLue Book of Gun Values
You will have to call Browning to find out.