The translation "I G" under the cyrillic prefix of the serial number was done by an importer. Prior to the large billboard import marks on receivers, a simple translation of the original serial to Latin letters was sufficient. There's likely a small/light import marking on the barrel near the muzzle or on the bayonet sleeve that you're not seeing. Otherwise, there are rifles that never received import marks. Regardless, the translation of the serial is a telltale sign that it is one.