I was running a combat course for a security company that has a govt contract today.
On shotguns, after being told OVER AND OVER, one guy kept his finger on the trigger when they were off target, or manipulating the safety; one dude went to low ready and tried to engage the safety on the Mossberg. It was tight, he squeezed his hand to flip it with his thumb, and of course his finger was on the trigger. The sympathetic reflex caused him to press the trigger, and BOOM!. However, he was pointed downrange towards the ground so no injury or damage. (except to his ego)