Not enough info
This picture doesn't give us enough information to confirm or rule out the possibility of a fraud. The profile does not appear to match US ammunition and guessing at its caliber from comparison with the woman's fingers puts it intermediate between a light and heavy MG. We have nothing in that range. Also, it's lack of copper jacketing indicates either a cheaply produced former Soviet Bloc weapon or a highly specialized alloy clad armour piercing round. In the latter case, its pristine condition may simply reflect it didn't hit anything hard enough to deform it before it came to a stop.
If I had to guess, if the picture is not a deliberate fraud, the little evidence we have is consistent with a non-standard weapon fired by the insurgents.