"If your Colt is early production it should be US marked as all initial production went to the government..."
That depends on what you mean by early. The first guns (some say 1000, some 2000) went to the Army. By the end of 1876, Colt had made about 33,000 SAA revolvers, but only 17,060 had been delivered to the Army, or just about half. The rest were sold on the commercial market. Several sources note that there are no U.S. marked SAA's between 20000 and 30000; the gun shown here is 29476.
Reklobe, the number on the loading gate and on the frame below it (under the trigger guard) is an assembly number; that number has no relation to the serial number except by coincidence.
Jim