Remember its not the caliber of the Firearm, its the caliber of the shooter...You have to understand the the 5.56 nato and the .22LR have roughly the same diameter the only real difference is the amount of powder the rounds have therefore stopping power, so yes a few well placed shots to the head will probably render you at least unconscious. Also the Gatorade bottle argument means nothing to me, because if I have a few .22LR lodged in my head I'm certainly not having a good day...and also remember the 5.56 nato was designed to tumble upon impact there in causing more internal damage, so I don't care if a 5.56 can pass through a gatorade battle and a .22LR can't.