I THINK THERE ARE MORE 4 DIGIT SER. # OUTSIDE THE published serial number ranges. I've saw another K prefix 3 AND 4 digit number on several of the auction sites...
I found this on the:
Springfield Armory Museum - Collection Record
Title: REVOLVER - COLT REVOLVER MODEL 1901 DA ARMY .38 SN# 2364
Date of Manufacture: 1901-1907
Catalog Number: SPAR 1885
Measurements: OL: 30.4CM 12" BL: 15.2CM 6"
COLT REVOLVER MODEL 1901 DA ARMY .38 SN# 2364
Manufactured by Colt, Hartford, Ct. - Standard 6-shot DA Model 1901 Army revolver with swing-out cylinder and smooth walnut grips. Blued finish. Weapon identical to the M1896 except for addition of an oblong lanyard swivel at the butt. Blade steel front, rear sight cut into frame.
Barrel: COLT'S PT. F.A. MFG. CO., HARTFORD CT. U.S.A./PATENTED AUG. 5, 1884, NOV. 6, 88, MAR. 5, 95. (Left): COLT D.A. 38.
Cylinder latch: K/2364
Frame: RAC & L.E.B. Indicates a Remington rework for home guard. 3/2364. RAC = Rinaldo A. Carr. LEB = Leroy E. Briggs.
Cylinder yoke: Z 2364.
Notes: "Special Report of New Work undertaken and New Supplies issued for Service. #46. April 1, 1902....SUGGESTION THAT CYLINDER OF REGULATION REVOLVER OPEN TO THE RIGHT. There was originally a diversity of opinion among Cavalry officers as to which was the better method, the right or left hand opening, but in 1894 it was decided that the cylinder should open to the left, as it was considered that by opening as it now does it allows the use of the right hand in throwing out the cylinder and replacing it." O.O. Letter No. 38078-7.