I've set up a "mission" using a P38, with the guns angled to shoot straight ahead at ground targets while sat/parked on the runway, and placed a series of buildings at increasing distances. The results so far seem to show conclusively that there are built in range effects causing decreasing hitting power as the bullets travel further. Changing the bullet flight time (?) which is usually 2, appears to affect the distance that the bullets become ineffective and how quickly they lose hitting power. Some of the tutorials available indicate that the bullets retain their damage points over distance but this seems to be not the case. Similarly I have been experimenting with damage boxes where aircraft typically have a separate "pilot" box, or fuel tank box, that is often completely enclosed in the fuselage box. Some of the tutorials have indicated that bullets will travel through one box and into the next, but again this seems not to be the case. Placing a damage box inside or behind another box does provide protection. I decided to put some serious effort into this as I was getting frustrated by some otherwise excellent visual aircraft models that were almost impossible to shoot down, caused by a combination of dp boxes within other boxes, and "systems" being damaged that CFS2 did not recognise. Some explosion effects such as "BOMB" seem to penetrate through DP boxes but the effects are variable, sometimes objects nearby survive and sometimes identical objects further away get destroyed. Other weapons such as rockets appear to be unable to penetrate through one DP box into the next.