First thing that springs to mind is that in CFS1, the point of impact is different depending what magnification you use.
Secondly, select a piece of blank sky and see where your fall of shot is.
Thirdly, if your fall of shot is way out use the small program 'Aim', this will put the fall of shot closer to the actual target crosshair and concentrate the fire to a single point.
Fourthly, when attacking your opponent get close...very close.
Lastly you could use DP Editor to increase the firepower of your guns......trust me a gatling on the front is cheating but it causes a lot of damage.
when you get good at using DP Editor try a C47 with 3 gatlings stuck out the side....bye bye tanks