1874 or 1875. IMHO, worth spending the money to get a letter from Colt on it.
Serial number shows it is a single action revolver made someime after 1978.
1962
1895
1927
1959
1897
1970
1910
about 1907
about 1880
depends on the model revolver. single action just in front of trigger guard............ modern revolver bottom of butt............
made about 1893