Another point I'd like to make...when a casing is ejected, it travels to the right, rearward and slightly upward. It does so at a fairly high rate of speed and never at the exact same trajectory. IMO that casing could have ended up literally anywhere in that cab due to ricochet, regardless of which position it was fired from. If fired from the drivers seat, it likely bounces of the top of the rear driver's side window. If fired from directly behind the passenger, it probably bounces off the rear passenger's side window. In both scenarios, the casing hits a widow at an angle and high rate of speed. Also, the weapon could have been held at any angle, my point being that the location of that casing proves very little, if you ask me.
Forgive me if this has been asked and answered already, I'm about 10 pages back still, but I'm curious if you know what kind of force would the impact from the shell casing ejecting have on the window? Would it be enough to break one, or not even make a scratch, does anyone know?