LOL, I have to chuckle at the mention of Jeff Cooper and his rules.
Because I guess very few people know this, but he himself had a ND once.
A friend of his recounted the story after he passed; it was in one of the gun rags, paying tribute to the Colonel.
Summary of itgoes like this" The Colonel bought a beautiful .44 Magnum Revolver and was showing it to his friend, admiring it and dry firing it while he pointed it at some kind of meter (electric?) outside his office window...click click click BOOM! A perfect shot through the window and into the meter.
He was stunned, and could only say "That doesn't happen to me..."
So, folks, ANYONE can have an ND...
To kill something as great as a duck just to smell the gunpowder is a crime against nature. - Alan Liere
Democracy is a device that ensures we shall be governed no better than we deserve. - George Bernard Shaw