What is the year of manufacture of Colt AR-15 Carbine with the following serial number SP 212104?

The Colt AR-15 Carbine with the serial number SP 212104 was manufactured in 1991. Colt's serial number system indicates that the "SP" prefix corresponds to rifles produced during that year. For precise information, it is always advisable to consult Colt's official records or a firearms expert.