102597-107596 Serial numbers used by Springfield Armory. The SRS does not list your serial number. It does show some around yours, but some are Army and some Navy. Sorry not to be of much assistance.
USMC 1969-1993 6333/8153/9999
USMC Combat Pistol & Shotgun Instructor
FBI Rangemaster
The revision to eliminate the lanyard loop was issued March 20, 1916, but the first Colt pistol shipped in 1916 was not until September 8, so the last pistol shipped in 1915, serial number 125566, became the last Colt pistol shipped with the lanyard loop magazine.
Colt serial number 337349 was shipped between June 15 and June 29, 1918. 2800 of those were shipped to the Navy, but only a Colt letter will indicate which ones.