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so, if the rifle is a 1903, and based on the serial number you posted, it is..they modified a real 1903A4 scope base, with correct rings and scope.
and its only held by 2 screws. stock is a cut...

no, it was never a sniper rifle.
what i would do, is sell the M73B1, and you will have enough money to buy an unmodified 1903.
and likely a better scope.
your receiver was one the last ones...