Yesterday I was diving (with very little E) over a zooming up P38, I had no E to evade and it seems he had little E also, so, we HO in the vertical plane with little gunnery result. Both of us continued straight without maneuvering and I saw clearly the "crash". I continued the straight dive wingless and the P38 continued the climb undamaged. He didnt evade but his FE didnt see the collission. It seems like me FE saw the collission earlier and his FE only saw F4U pieces passing by. Later, again against a P38, I was without ammo and saw a P38 just above me, I was faster and decided to ram it on purpuse. The P38 pilot was unaware of the aproach and "crash", my plane was broken in half and, again, the P38 continued undamaged. Finally I dove over another P38 in a P51, but I got too close and, while rolling slowly, I was unable to evade the crash, again, P51 wingless and P38 undamaged.