Great discussion and pics! I've gotten to the point where I almost don't see an
entire helmet when I look at those pics. . . I just see little sections of damage. 
But that third pic Raf posted in post #29 is very interesting. In that pic, whether it's
due to lighting or the angle, it seems that the lighter "upside down C" under the dent
matches the mandible gray, while the other gray is slightly darker. Hmm. . .