Firing the AA gun.. need advice

[jscharpf]

Just starting out and I'm wondering what advice anyone can give me with regards to firing the AA gun. I've had my first experience with a very slow Japanese plane passing overhead multiple times.. at first I assigned a guy and he just fired and fired but never did anything, then I took over..
OK I tried everything I could.. I wasn't just spraying.. I tried leading.. I waited until the plane was directly overhead.. just feet above me.. and I never seem to even score one hit. He just kept passing over slowly.. where I feel like I would have been better off with a pistol.. he was that close.. but my AA gun just kept firing into him.. no hits.. nothing..
Am I missing something?

As an alternative, is there some setting that I can change to make my gun a little more accurate? (I know I know it's cheating but so is playing a simulator lol)

TMO 2.5
RSRD 5.xx

Jeff