most likely 1904 or 1905. Gun apprears to be in great condition. You might consider lettering it. (getting an official letter from colt) There is a charge for this service but a letter would GREATLY enhance the value of your gun, and tell you if it's in it's original configuration and where it was originally shipped to. The guns barrel seems to be a standard 5 1/2 inch. The grips (Colt calls them stocks) are most likely aftermarket, but could be original. Congratulations on an exceptionally nice first generation Colt.
Mark Lane to William Buckley: "Have you ever referred to Jessee Jackson as an ignoramus?"
Buckley: "If I didn't, I should have"