The number on the butt is a U.S. service number, not Colt's serial number. The serial number in the one stamped on the frame behind the crane, and you have to swing out the cylinder to see it. The factory (Colt) serial number falls within the regular New Service Model series, and started with #1 in 1898 and continued until 1944 where they ended at or around 356,000.
The Model 1917 revolvers were made during part of 1917, 1918 and ended during early 1919. The Colt serial numbers were in the 150,000 to 301,000 range at the time. The Army services number (stamped on the butt) cover the Model 1917 only and start at No. 1 and end around 151,700. A handful of commercial Model 1917's were made after the war, but do not have military markings.
Colt started shipping revolvers with the newer style cylinder at service number 30,451 - but because they still had older cylinders to use up I would not be surprised that a gun in the 35,xxx range showed up with one.
Very few of the bored through chambered guns survived, let alone ones that are still in excellent to mint condition. You are sitting on a lot of money there. I wouldn't shoot it either.
If you will provide me with the full service number via. private message I will try to find a closer date of manufacture.
