Could someone from HiTech chime in on this??
I doubt anyone from HTC will answer this or any other little or minor question. HTC only has a few people working for them, and even fewer when you get down to those who might know the answer to this. They are way to busy working on upgrades (I hope!) to worry about spending time answering all of these questions over and over again.
As to the question, there is only two reasons why someone would ask it....
1. curiosity, which I think the original poster was thinking. With the explanations here, I think the question has been answered pretty well here. Small caliber rounds are sealed, cannon rounds and multiple hits (big holes) are not.
2. to complain. If they answer "yes it is modeled here" we will get the complainers complaining about the fuel leaks they get ALL THE TIME ! If they answer "No they are not modeled here" they will get the "but it was in the real war !!" compliants.