That Python would be a 1974 model. A online site for Colt dates would be: http://proofhouse.com/index.htm
Generally around the mid 1970 thru the strike years was when Colt quality started to drop. You still have to judge each gun on it's own merits, but the master gunsmiths that built the Pythons started to leave the factory (retired, left during strike) and with that lost in talent the revolvers on a average suffered.