Well in reality base ack does not fire when friendlies are there, so +1 for no ack.
Is is obtuseness for the sake of it, or must I really be as specific as to say that I meant when the ack is firing at enemies?
IRL, ack was indiscriminate.
Since this id NOT real life, how about a 10-15% chance of friendlies getting damaged by it? Even 5-10% would be interesting while compensating by making it another 5-10% more lethal to enemy aircraft.
I bet there would be a lot less ack dragging.