I picked up this shotgun, pretty sure its an early one, maybe produced between 68-72. Blue scroll engraved receiver, 25" barrels choked SK and SK...my question is has anyone seen one of these that does not have any markings on the top of the barrels?? There is nothing on the barrels to indicate mfg., gauge..nothing. Appears to have an ivory front bead and a small silver mid bead. Does anyone know of a resource to check the S/N for more information?