Your money would be lost then. The problem is not with the hardness of the ammo bunkers in AH, or even shore batteries. The problem is in how you are picturing the scenario. After you drop 2500 lbs of hardware on a shore battery (for instance) there would not be a lot of concrete left to push through. In the case of ammo bunkers they have much, much less hardness. .50 cal API was designed to punch through much harder stuff.
At some point you guys will possibly start to consider that hitech did put some thought into his game.
Forget AH. I'm not talking about AH, I'm referring to the real deal. In AH, ammo bunkers are far too easy to destroy via any weapon. In the real world though, even a direct hit on 4 ft (or thicker) reinforced concrete with X weight of bomb isn't a for sure thing. A near miss would scratch the surface, maybe.
If you think it is worth while for a .50 cal (or 6) to sit and hammer away at a reinforced concrete bunker, and that it is truly an effective way to breach/destroy the bunker in question... then reality escapes you.
btw... HTC put the typical OBJ at the same hardness for a reason: game play. Nothing more. It allows for the most platforms to be able to get the job done, it certainly isn't representative of "real world" fuel tanks, barracks, radar towers, town buildings, ammo bunkers, or the multitude of strategic buildings within the factories.
oh, and on your "API" kick, go check and see just how much more effective AP is vs FMJ really is, especially vs the different mediums.