They had some extra parts laying around and assembled them. Nice looking M39. Check on the 7.62x54r website. It explains about "sneaks" Number on side of receiver is the Number assigned to it by Century, for the importation paperwork. Most Mosins had no serial number on the receiver, only on the barrel. The Firearms act of 1968 requires all firearms in this country to have a serial number on the receiver. Europe sees the barrel as the gun, we see the receiver as the gun...