I haven't really messed with the AA gun since 1.0.2, but it definitely worked back then. I think the devs had enough of people tilting it to point forward (the cab rotation trick, witch still works btw), so they reworked the code and now the gun doesn't even fire, when it's in the "wrong" orientation. Unfortunately, they also introduced this bug, turning the gun from kind of useless to perfectly useless.