We thought we were purchasing an antique Colt Navy, square trigger revolver (sn 1485) at an auction several years ago. Then we started questioning it. We even sent it back to Colt to see if they would verify it, but all they said, when they returned it was that their SN records didn't go back that far. The Serial number doesn't seem to be a continuation of Colts, as some commemoratives were... I am starting to think it is either a 2nd Gen, or a Signature Series Colt. All the markings are Colt markings. How can you tell a 2nd Gen. model from a Signature model? Regards, Joanne