currently when you shot HE rounds from vehicles (IFV and attack choppers) at high rate of fire, impact sound fail to be rendered for each impact, and for certain vehicles (ah99 blackfoot) it's not rendered at all.
the engine seems to skip rounds sounds if they impact at the nearly same time.
if you fire 3 round burst all three round should be audible from each others.
make as many impact sound played than rounds shot.