Sounds like "dear old dad" stole the rifle from the US government. At any rate it is a highly sought after treasure if original. Were it me, I would report the rifle to the Army as having been left to me by my father and get a clean bill of health. If you want a unbiased assessment then you need to post pictures and details as to the crosshair, serial number, mounts and any other info. The Z prefix was used for the Remington sniper 03A4 and the M82 scope is rare and very expensive. Regards, Rick.