Air Defense Cannon Bug?

Before I begin, this may not be a bug, but I wanted to report it anyway just in case it was. So, it seems like with those air defense cannons on Liberation Peak, you can be shot through them. Maybe you're supposed to be able to shoot through the netting on top? I was getting headshot by snipers multiple times, but when I had an enemy in one that I was trying to shoot through it, it almost seems like the back steel plate of the cannon you can shoot through. Not to mention, the player's backpack is coming through the back of it. Anyway, I was unsure if you were supposed to be able to shoot the man in the cannon or if it's only supposed to be blown up by rockets, missiles, and high penetration rounds.