I think your enitities/wmps have a very large scale, PhysX doesn't like that!
Try different values for the

pX_SetWorldSize(0.05);

and

pX_setgravity(vector(0,0,-9.81));

you have to set pX_SetCCD(1); try it after the level load
and set pXent_SetCCDSkeleton(barrel,vector(0.25,0.25,0.25),1); only for the barrel objects!

also pXent_SkinWidth(barrel, 0.01); might help