AD is a malfunction of the firearm
DA is a malfunction of brain behind the firearm
Rule #1 keep booger hook off of bang switch until you are safe and ready for BANG.
40 years ago, I was young and dumb.
A co-worker had asked about the possibility of borrowing a rifle to go deer hunting.
I took him to gun club and instructed him on use of my old, sporterized 03A3.
(His telling)
He booked a 1 day hunt on day lease. Drove up the evening before and slept in his truck.
Got up and went to the orientation, then was driven to his stand.
He fell asleep and woke up to sunshine a huge buck 40 yards in front of the stand.
The rifle was sitting on the blind floor, between his knees, muzzle up. Staring intently at the buck, he wondered if he loaded the rifle? So, he leans forward, takes his thumb and pushes down on the trigger.
.30-06 going off inside a box blind is not fun. Luckily, leaning forward, the muzzle was above his cap bill.
He did not get a deer.
AD? No
DA? YES!!!!!!
I have NEVER lent a gun, where I was not present, again.