"...right down to the person in field..." Nope. Those records were unit level records and were not kept by any military service for any issue weapon. Some M1's can be traced, for a fee, to a unit, but not all of 'em. For most military firearms ALL arsenal level records of which unit got what rifle have long since been destroyed. I'd bet the CF has destroyed the records for C1A1's etc, too. No point keeping records for a rifle not issued anymore.
"...the same rifle he carried during..." A miracle! The guy should have run out and bought a lottery ticket.