found something else, you can use the vertical lines on the horizontal line of the crosshair to correct your point of aim on moving targets. Formula: distance to target / 2 = on which line to fire on. For example, 500 meters equals 2.5 lines you have to aim ahead of your target. This was tested on the target range mission for arma 2. Got headshots all the way up to 800 meters, which is this guns max range, I think.