Good theory, but if its a flat surface,why the gap between strike 3 and 4? A bullet would rip through it... as a i said, the hole is square. Nothing about the pic says bullet. At that angle of trajectory, a bullet will have 1 skip, not 4 especially on expanded metal in a gap no longer than 3"
Because the third strike is still into the expanded metal on top of the square frame. It is not yet deep enough to touch the tubing, but it is close.