Karnak is correct, AH does model kinetic energy of rounds, both in the actual drop in velocity and the resultant effect that has on damage.
Back to the topic of this thread: A single .50 could pass through an aircraft leaving 2 half inch holes that would be fairly inconsequential and that a metalsmith could repair in an hour. It could also cause catastrophic results. This difference between the two could be the result of less than 1/2" of bullet placement. Some planes of the same type withstood tremendous amounts of hits while others went down with very few hits. That's just reality.
The inherent paradox of damage modeling in simulation is that the more realistic you make it, the greater the number of possible results. The greater number of possible results, the less the consistency. The less the consistency, the less the people think the damage model is realistic. It's a crazy circle.
Bendover's (and I'm not picking on you, I understand where you're coming from) response typifies most people's view on it. The famous last words of Union General John Sedgwick are purported to be "They couldn't hit an elephant from this distance," just before he was shot dead by a Confederate sniper. The difference between that and simulation - in real life it's chance, irony, a cruel twist of fate. In simulation people call it B.S when that happens to them.
But I digress, we are making a lot of improvements in this area for AH2 and I'm really looking forward to it.