to add to what bruv said:
if you're in a field or ship gun, you cannot hurt friendlies or friendly objects, period. if you hit them, it does nothing to you or them. If someone complains that youre shooting at a friendly base or shooting at friendlies, tell them to get bent.
friendly AUTO ack CAN hit you if its shooting at a bad guy and you get in the way..
if you're in a plane or a vehicle, and you hit a friendly, you will take damage.. if you hit friendly objects, it does nothing.
so, your idea of using the 8" to harass the wirble in town was actually quite sound