Problem is there's no modifiers to the total damage inflicted based on hit location. 10-20 rounds of .50 cal shredding a Spit's wing and sending him tumbling to the ground should count for more than the 5 or so 20mm to the fuselage that caused no damage other than a few holes that bought the other guy the kill.
Hit location should be weighted with the type of round and amount of hits.
This would also help put a squash on guys who like to spray a dying target trying to steal the kill before it goes splat.