Great kit score, congratulations! Based on the most superficial of evidence, IMHO its probably Romanian. Look for any cyrillic letters not common to Roman letters, or vice versa. I believe the tip-off is that the "Y" stamp is a Roman rather than Cyrillic (У) font.
To be clear, I’m referring to the “Y” letters that are stamped, not the circle with the “У” in it. The circle-У symbol is common to both Romanian and Soviet/Russian barrels.