A more likely use test would have been what happens to the stock when its used as a club to buttstroke someone. Get a dummy dressed up and start wacking him.
Thats always been a weak point of the ar15 design. They dont hold up well as a club when the bullets run out.
Its not a terribly valid set of tests since there was no firing the rifle after stock failure. Did the stock failure allow the buffer tube to distort?? even if a stock breaks and collapses the more important issue is does the buffer tube still work??
Those tests are interesting but not relevent since there was subsequent test fire.
"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." — L. Neil Smith