The marking looks cut w/a pantograph,,the type that uses a tiny high speed rotating cutting point. Not that dismisses or proves anything,,just a point of info. Cut thru the blue finish of course.
?--If the wording 'USMC Property' was instead 'Property USMC' make any difference in the thoughts about the validity of the marking?

Would a factory letter solve anything, seems like they;d be buying direct and not thru the local hardware outlet.

Nice clean gun at any rate!