Come on Homeless! What part of putting the muzzle of a gun in your mouth or pointed at your head don't you understand is a poor safety practice. If you want to blow through the barrel get a tube and blow from the percussion nipple or from the flash hole and keep the muzzle pointed in a safe direction. By the way, I can cite authority better than your range officer friend having years of experience on military range operations from small arms through mortars and tanks and now as a NMLRA Trainer responsible to teach instructors. It is simply a bad idea and violates the most basic firearms safe handling rules (Treat every firearm as if it were loaded, Always point the muzzle in a safe direction, Be sure of your target and beyond).