All that's needed for effective defensive firearms use are marksmanship, a basic working knowledge of the human anatomy and a willingness to act under pressure. We use humanoid targets to reinforce aiming points, not to "desensitize" ourselves to killing. That's hokum. Unless you're a sociopath, you will have a moral aversion to using lethal force on someone not deserving of it. A more likely possibility is using unnecessary lethal force, based on an unreasonable fear due to a lack of training and experience.
What does work is stress innoculation. Force on force training with simunitions, edged weapons, grappling and ground fighting are good for this. So is hunting big game. Those things will teach you to manage your emotional responses and reinforce your OODA Loop.
What does work is stress innoculation. Force on force training with simunitions, edged weapons, grappling and ground fighting are good for this. So is hunting big game. Those things will teach you to manage your emotional responses and reinforce your OODA Loop.