Back when I was more "politically" active instead of just bitching like I do now; I was collecting failed expandables in order to try and show the DNR that they were unacceptable and should be outlawed.
It didn't take long to fill a shoebox and all of them were compound guys.
I guess that's apples and oranges really.
As far as a head failing because it hit a rock or a barrell, no-one REALLY considers that a failure do they? I mean, your head will split open if it hits a rock at 180fps but I wouldn't consider the skull failing.