Japanese hull mounted machine guns are the only ones in the game that are actually usable, but this comes with a major unnecessary drawback.
The tanker sitting in the MG position Will prioritize staying in his seat rather than switching to a more useful position, as opposed to the machine gunners of every other faction who know that they’re just spare crew for when someone more useful gets killed.
This results in infuriating moments where you can’t get a gunner, loader, or driver because you’re next to useless machine gunner is too stubborn to do anything useful. A prime example is when your tank is hit in a duel and your gunner is killed, but instead of manning the main cannon to kill the other tank your machine gunner decides that his 7.7 mm piece of utter dog shit is just too important to give up, resulting in your entire tank getting destroyed.
The fix is simple, make every other seat in a Japanese tank have a higher priority over machine gun. It’s a quality of life change that would make having a functional hull machine gunner not a literal downgrade.
