This is completely true - when we were doing our infantry battleschool in Wainwright in '89, one of the girls on the course picked up the 60mm mortar, took off two tags and proceeded to drop the thing in head first. I swear the entire platoon flew face first into the sand. Of course in the back of your mind you know it wouldn't (gulp) go off and plus the firing pin had to be manually pulled as it was training, but nonetheless, it scared the crap out of us all.