Speaking of Myths....Myth Busters on TV, supposedly busted a myth several years ago, that leaving a laser bore sight in the end of a high powered rifle barrel, and firing a round having forgot it was there would peel the barrel back like a peeled banana.
They couldn't repeat it, so called it "busted".
However .... I watched my wife's nephew's son do just that with a brand new Remington 700 BDL chambered for 7mm Magnum! He was wearing shooting glasses and nary had a scratch. (tough action!) I was tasked with taking the gun to my home town's best gunsmith to see if he would put a new barrel on it......the action looked fine. The gun smith took pictures of the rifle, but wouldn't touch it otherwise. He claimed the action was most likely compromised enough to make the gun unsafe......so I took back the bad news....and they displayed it for a while, then chucked it.
I'm guessing the Myth Busters crew, didn't try it on a high pressure round like the 7mm Mag.
(I wish I had done what the smith did....take pictures! Then I could've shown them off here)