I think we have nailed it. The stock marking, though very blurred, appears to be the Colombian eagle, and the rectangle below it seems to have the numbers "19?2" which could be 1912. The Steyr Model 1912 carbines had serial numbers prefixed with an "A", and had "C" on all the parts. They originally should have had the Colombian crest on the receiver ring, but that appears to have been removed, either deliberately or by neglect.
For those who have Ball's Fourth Edition, check pages 104-107 and see what you think.
(My Chinese guess wasn't bad, both countries start with "C", and I was only wrong by a continent and 10,000 miles or so. Maybe I should be Secretary of State - at least I know where China and Colombia are!)
Jim