As silly as it might sound, I would be willing to bet that this is the biggest obstacle that most people would face in a 'home intruder' situation. It's one thing to be well practiced and to want to do what is necessary - it's quite another thing to actually act. Once the trigger is pulled, life changes drastically. You can't unpull the trigger.
“You can’t unpull the trigger.”
There’s a C&W song just awaitin’ to happen right there!