As an NRA and State Police certified firearms instructor a component of the courses I teach involves educating students about what kind of force is necessary for self defense, and as a member of the armed forces and veteran I have basic training in combat trauma management. The interaction of bullets and biology is known as "terminal ballistics," and is widely reported on by medical professionals, scientists, law enforcement personnel, and the military. The intended and actual effect a bullet has on the biology of a target, whether it is while hunting or in a self defense scenario, is crucial in selecting a firearm and understanding its proper employment in various scenarios, as well as treating gunshot related injuries. In this article I will try my best to highlight the key points of various studies I have read that deal with the intended and actual effects of various bullets on the human body.
When shooting for self defense it is important to understand there are three primary functions a bullet can have on a target to stop the threat. The first of these is through catastrophic damage to the central nervous system, the next is through mechanical structural damage to the body, and the final is through massive hemorrhaging and subsequent loss or diminishing of consciousness. As firearms instructors we teach to shoot to stop the threat. Through this we hope that should the presence of a gun or single gun-shot not be enough as a psychological block to stop someone from being attacked, the victim realizes that at that point they are probably going to need to cause a lot of physical damage until their life is no longer in danger.
We teach to primarily focus on shooting the center mass, or torso of a person, rather than going for other areas of the body. Under a high stress, dynamic situation, it is unlikely that one will be able to hit the smaller target that is the core of the central nervous system, contained in the head and spine. One's torso provides the largest target, and contains the majority of vital organs. In a life or death situation, especially a gun fight, every second counts. The unfortunate reality is that when stopping an aggressor, physically incapacitating them in the shortest amount of time means being able to inflict the most damage in as little time possible.
When a bullet passes through or into the human body, it creates a permanent and temporary wound cavity. The temporary wound cavity can be many times the diameter of the bullet, and in and of itself can cause extensive damage. Handguns, the primary self defense tool of Americans, use lower velocity bullets which cause a much less dramatic temporary wound cavity than a rifle. For that reason, I recommend hollow point ammunition for defensive uses such as concealed carry, as it is designed to expand which increases the amount of damage to the intended target as it passes through. Likewise, I personally use a rifle for protection of my home as the nature of the ammunition lends itself to being able to cause more damage than handgun ammunition, in addition to other benefits dealing with accuracy and repeatability of hits.
While it may seem dark, the ability to cause as much damage as possible is very important. If a person continues an attack after being shot or even under the threat of being shot, it is likely due to some sort of impaired neurological function, whether it is adrenaline or drugs. In the instance that an attacker is not reacting to pain or fear, it is very possible that they will only be stopped when physically unable to continue. Generally, shutting down neurological function or damaging nerves or the spine extensively is the fastest way to do this, but the head and spine is a small target. If massive hemorrhaging is caused, a dramatic drop in blood pressure can also cause a loss in consciousness, though this will not occur as fast as damage to the CNS. Understanding the type of bleeding associated with damaging the heart, liver, spleen, and lungs, as well as the major thoracic arteries and veins helps explain why this is such an attractive target to stopping a violent criminal, rather than the small target of the head.
Understanding the potential damage that can occur when someone is shot is equally important when treating gunshot wounds. One of the big things we are trained to look for in the military is entry and exit wounds in the chest, as a sucking chest wound, or pneumothorax, is very common in gunshot wounds to the chest. We also are trained in needle decompressions in the case of blood entering the pleural cavity, this is known as a hemothorax. Other types of expected bleeding based off various injuries sites, for example the arteries in the legs, are taught to be treated through compression and clotting compounds, as well as tourniquets. Obviously doctors who perform emergency and follow up surgeries must understand the kind of trauma to the body they can expect from gunshots from rifles, shotguns, and handguns.
There have been many books, articles, essays, and personal accounts written on the topic of bullet effects on human bodies. These studies are important as they allow for better training of military, law enforcement, and civilians, better development of firearms and ammunition, and better training of first responders as well as doctors and surgeons. This brief summary was meant only to give the most basic overview on how gunshots are intended to effect the human body, and what kind of damage and subsequent treatment can be expected. I have included many good links throughout the paper from perspectives of medical professionals, to at home tests, to sanctioned articles for and by the military. There are literally thousands of pages of information on this topic in the public domain, and I highly encourage those interested in medicine, self defense, or both to sift through.
Michael Ball (1)