HEI rounds proved to be very effective aganst aircraft that is whay so many countries used theam aganst aircraft targets, they felt it was a better way to bring aircraft down. Blow away controll surfsaces, set fires , ect...You get more bang for your buck for less weight in an aircraft, HEI ammo is very effective and less weight than AP ammo like the 50 cal round. Ap ammo make nice holes in an aircraft HEI blow's it away. This debate has raged on and on in the end it seams as though the effectivenss of the HEI type ammo is Heigh, it is also a short film, how long did that P 40 remain in the air? I have read numiours acounts of C 202 combats whear Spit's blew up after asorbing damage from the 12.7mm HEI rounds.