Choice of AP or HE?

[Dion]

I believe AP stands for Armor Piercing ammunition and HE stands for High Explosive ammunition. In some situations one type of ammunition is better than the other. When both types of ammunition is listed for use by a particular weapon how do you know which kind will be fired? I guess it dipends on if the target is a hard target or a soft target, and the computer just decides which type works best. What bugs me is some units will have both types of ammunition listed while only one type of ammunition will be fired unil that type of ammunition has all been used-up. In some situations that really causes problems because you might be forced to fire HE ammunition at a tank and not beable to use AP amunition until all your HE ammunition is used-up, which usualy means waiting for most of the game after you have been shot at multple times, and only surviving if your very lucky. Is there a hot key or some command I can use? Or am I using my units unrealiscally?