I have a theory. If you watch laggy planes from above, the "shot" appears to originate behind the moving aircraft. From a machine language/ 3D point of view, I thik the shot is called for at a point in space X,Y,Z pointed towards x2,y2,z2. The lag means that some seconds of real time pass, then the tracer appears, moving through the firing aircraft.
If you are close enough behind it when it fores, you are in the path and thus struck. I try staying back from laggers or to the side. When they are flashing, just pick a point on either extreme end of flashing and hold fire there, you will get them.
Sometimes the plane "jumps" forward and several called for shots appear at once; the "shotgun effect". Sometimes planes fire "lasers", where the tracer doesn't move forward and disappear at the normal time interval, rather stays with the aircraft on firing and stays at range, looking like a series of lasers.