Not that interested in the trunnion markings on the side (circle 10 is Bulgarian BTW. The 2 digits you don't remember refer to the year of production for Bulgarian rifles, and the '1962' is the serial which if matching numbers kit should appear on the bolt, carrier, top cover, etc).
More interested in the stamp number on the top of the trunnion. My guess is it's a 4.
Regardless I'm with kcstott.
Send it back. Too loose for even a knurl.