The number on the BUTT on a COLT 1917 is NOT the serial number-but the Army number.
The actual serial number,put on by Colt,is on the frame under the barrel,and can also be seen on the inside of the cylinder crane when that is opened to read the frame serial" there. The 2 numbers should match.
Colt 1917's were part of the New Service series,and used their serials(which started in 1898). By 1917,the figure was in excess of 125K,and the Army 1917 model New Services,had butt numbers starting at 1-so they do NOT match.
S&W,numbered their 1917s in a separate serial number range from their other large frame revolvers,so the serial number AND the Army numbers-MATCH,since BOTH started at 1
Not aware of any original Army numbers on the cylinder latch.Colt put assembly numbers(not serial) on the cylinder latches of their earlier Army/Navy revolvers(1889-1907),both civilian and military purchases.