Don’t want to be dramatic, but can any of you ex-mil types tell me if a bullet can make anything other than a round hole, especially in a curved panel?
If it not be the first thing a bullet would go through, you could get similar hole because some bullets tumble, and go out sideways. But the size and shape of it... I think you could rule out anything except the steel core of 7.62 AP ammo. And I don't think you have enemy's with AKs or SLRs and military surplus ammo
So... if no other holes anywhere else, or deep scratch marks, than this is not a bullet exit hole.