First off, one of the hardest shots to make is from a dead six. The reason for this is the profile of your opponent, from the six o'clock position he presents a very slim target. Dead sixing a P38 is a good example. From that position a p38 is very slim and a poor target. Get that 38 in an off angle and it becomes very big.
Secondly, your gun convergence plays a very big part in how many BB's are going to hit your target. This is a personal choice, IE you need to figure out at what range you generally start to shoot. (Do you get in close? Do you like to shoot from 200...300...400 yds?)
Generally, once most people get the hang of this sim, they shoot under 400 yds. I personally set my convergence as a default to 300 yds, but will change it as the fights in the area dictate ( I never set convergence to longer than 300, but often set in closer), but that is me, and not necessarily where you need it.
Thirdly, G-forces have alot to do with your line of fire. If you are pulling positive G (IE you are in a tight turn), your BB's are going to fall under your nose. If you are in a negative G situation (IE you are in a dive and pushing your nose over) your BB's will rise above your nose.
Many times I will pull the trigger as my opponent disappears under my nose in a turn. Remember, once your BB's leave the A/C they will go in a straight line, while your A/C will continue to depart the shoot angle.
Lastly, please avail yourself of the training arena. If there are no Trainers there, there is usually at least an old fart like me there who would be more than willing to help you out. There is also some ground targets there to practice on.
Hope this helps a bit
cheers,
RTR