What you have here is a very early 1905 Ross Military Mark II rifle. The serial number is 610 over 1907 X. It has been upgraded to 3* specifications.

Ross serial numbers started with the numbers 1 to 999 over the year and the letter A. At rifle 1000, they began again at the number 1 over the year, and the letter B. This continued for another 999 rifles and then changed to the letter C, etc. and continued on to X,Y,Z. When it got to 999 / 1907 Z, the sequence changed to TWO letters, those being AB to AZ, then BC to BZ , etc. and continuing along when the sequenced changed to CA to CZ, then DA to DZ and so on.

Commercial Factory Ross Sporting Rifles had a serial nunber stamped on the left side of the barrel, in very small (1/8 inch) numbers. In some cases, the end of the butt stock and the inside of the Butt plate was also stamped with the commercial serial numbers.

Your rifle originally had a threaded type of firing pin and sear/cocking piece. One of the upgrades was to replace this with a firing pin and sear/cocking piece that could be disassembled more easily. This unit had a small cross pin that held them together.

There were over 70 modifications to the Mark II, most of them minor or cosmetic. Only the major upgrades were marked and designated with the * designation. These ususally included a major sight change or something similar. As far as we can determine, all the U.S. purchased rifles were Mark II *** rifles.