Gah... As much as I like not having to drive backwards with that thing, it's so jarring to see the Auto cannon go through the driver's head and firing. I wouldn't be opposed to seeing it brought back to it's regular firing arc and have it's armour inverted (Rear in front, Front in rear).
The reason this happens is because all MG's have the MG fired from a crouched position. Even the Maxim and DShK get this mode if you put them in Cover or a Building. But the M2HB does not have a standing mode because the the M2's tripod cannot be adjusted. So even in Heavy Cover or in a Building, the M2 will always be laying down.
I suppose they could have a variant where the tripod is removed and the gunner sets the gun a few feet off the ground and crouches to fire, but since the height of walls, objects, and windows vary greatly, this probably wouldn't look any better.