Is there a easy way to date a colt for example I have a gold cup national match 1911 with the first three digits a 71N****
Good one.Treat it to a box of expensive ammo or take it to see a nice movie, like Way of the Gun or The Wild Bunch.
Sorry, couldn't help myself. The prefix 71N was used for all the new reproduction Series 70 Gold Cups so it won't help to establish a date of manufacture. Your best bet is to call Colt at 1-800-962-COLT or else look up your serial number on their website and see if it comes up: Colt's Manufacturing LLC