Collision model problems

[xXpyroHatakeXx]

I created a collision model that looks like this in blender:
[IMG]http://imageshack.us/a/img9/3186/blenderrenderapc.jpg[/IMG]
All of the mesh is weight mapped to their respective bones.
But when I view the model in the sdk, the model's collision mesh shrinkwraps for some reason like so:
[IMG]http://imageshack.us/a/img832/4290/mdlviewerapc.jpg[/IMG]
Here is the relevant part of my .qc file:

$collisionjoints "phymodel.001.smd"
 {
	$mass 2500.0
	$inertia 1.00
	$damping 0.00
	$rotdamping 0.00
}

What might be the cause of this?

[xXpyroHatakeXx]

After talking to other sources, I found a work around, but I still bet there is probibly a better way. I'll explain what I did so that other people who may stumble across this thread with the same problem may have an idea of how to fix it.
I fixed the shrinkwrapping over the entire model by removing that bone on the ground. Then I only had to deal with the shrink wrapped body of the apc. $concave doesn't work as this is an animated model with several bones. So I got creative and added 2 more bones to the reference and collision models. I had to add extra geometry (2 faces ea.) and weight them to the reference model, otherwise the bones would disappear on export. Why the extra bones you ask? Well I read that having the geometry in seperate smooth groups would yeild no shrinkwrapping, well that is a lie. I also had vertices weighted to 2 seperate bones, creating an overlap that didn't go over so well won the compiled the model. So I had to split some vertices. After seeing that all the collision that I wanted sho up in the model viewer, with a few extras that I didn't want, I decompiled the model to edit the collision mesh that Source had already "accepted." I did this because the collision was close on the model to what I wanted and had all the parts, but wasn't quite to what I wanted. After editing the decompiled mesh, and making changes to prevent antlions from getting stuck in the wheel well, I recompiled the model with the new collision and it was exactly how i wanted it to be! :)
Here is a picture of what my final product looks like. The mesh may be more compilcated than the regular combine APC, but when you're driving it (heavy player interaction), you want it to be more accurate of the actual shape.
[IMG]http://imageshack.us/a/img7/4813/finishedapc.jpg[/IMG]