If that is the actual serial number I would be very cautious.
I can borrow a 74L rifle which is not a sniper on Sunday - the owner is on night shift so I wouldn't want to bug him now.
I sold a 2nd 74L rifle to another friend a few years ago...
I've owned an 80L and a 90L rifle which were not snipers.
The "sniper blocks" are within a specific 500-999 number "block". There are non-sniper rifles which exist just outside of those blocks.