My friends (no joke) found an AK47 in the mountains

In Sunday my class went on a trip to Mongol Nomadic Tourist camp, and we had an hour or two before we left. In that few hours my friends went to the mountains near the camp, and apparently they found an AK47 and a F1 or RGD-5 grenade? They weren’t too sure about the model. If you asked “were the guns operational” unfortunately they weren’t since the weapons were seriously rusted. The AK said “КПШ АК47 1947 or 1949” something along the lines, and after digging a little bit, the gun was a training gun for what I could assume for the Mongol People’s Army at that time.