I'm sorry if I'm harping a bit but until the damage model has been fixed blaming the lack of kills on just poor gunnery is a bit off. I can continually take out ailerons, rudders and elevates on spits without changing the way they maneuver. These are vital parts of an AC. Damage them and it should be a lot easier to make a Kill shot.
I might come of sounding like an amateur but I've been playing IL2 online with full real for a while now and have managed a reasonable Kill/Die ratio. At the moment you have to kill the pilot to be sure of bringing down a target. Some people are really good at it too. I'm not that good at at head shots so I go for easy shots then maneuver for another, voom and boom.