Example of various handgun and rifle bullet calibers

Forget what you see on TV. The reality of gunshot wounds and terminal (death inducing) gunshot injuries is remarkably different from what is shown in the movies where the gunman appears to have an unlimited supply of bullets, gunshots knock the enemy off their feet, and gunshot victims make long, drawn out confessions as they slowly bleed out. The reality is: stopping a person cold in their tracks with a gunshot is difficult to do and depends on shot placement, the type of ammunition, and a little bit of blind luck.

What is “stopping power”?

Stopping power is the ability of a firearm to cause enough ballistic trauma to incapacitate (and thus stop) the target – preferably immediately.  The stopping power of a firearm depends on various factors including bullet caliber (the size of the bullet), bullet velocity, mass of the bullet, shape of the bullet, what the bullet is made of, and the type of firearm used to fire the bullet.  The relationship between these factors is complicated but in general, the characteristics that impact stopping power the most are bullet caliber, velocity, and of course, shot placement.

What types of bullets to law enforcement personnel use?

Bullet exiting a pistolWe can learn a lot from law enforcement’s choice of ammunition which is typically selected according to FBI ballistic laboratory testing followed by real-world performance tests. Most commonly, law enforcement use hollow-point or expanding full metal jacket bullets which tend to “spread” after impact and thus, cause more tissue damage. Calibers used by law enforcement are almost always pistols rounds, typically .38, .357, 9mm, .40, and .45.

Do police use ammunition that offers the best stopping power?

Given their usage by law enforcement personnel, we would assume these types of rounds provide the best “stopping power” – the ability to stop an enemy quickly – dead in their tracks. This is not entirely true however. Law enforcement use pistol calibers that provide adequate protection in a convenient package but rifle calibers (e.g. .308, .30/06, 7.62×51, 30-30) provide much better stopping power primarily because the velocity of the bullet is much higher than a pistol round. Although the shorter barrel of a pistol restricts the velocity of the bullet and the ability of the shooter to control the gun’s recoil, a smaller package is much more convenient for the shooter. In short, police use pistols for convenience, not stopping power.

How a bullet damages the human body

Shockwave created by "hydrostatic shock" or hydraulic shock"To understand a bullet’s effectiveness, we must understand how a bullet damages human body tissue, the extent of which depends on the size of the bullet (the caliber), the bullet’s velocity, and shot placement.

A bullet entering an enemy’s body does damage in two ways. The projectile tears through the body causing tissue damage and creating a wound channel.  This type of damage is known as “permanent cavity”.  The primary result of permanent cavity damage is profuse bleeding.

With the second type of bullet damage, the body absorbs the bullet’s energy in front of and around the path of the bullet, causing nearby tissue to stretch and expand as it passes through tissue. This same effect gives a bulletproof ballistic vest the ability to stop critical injury. The ballistic vest spreads the forces over a greater area, outward from the bullet, and reduces the impact to the person wearing the vest.

This spreading of force through the body, known as “temporary cavity”, is governed primarily by the bullet’s velocity and caliber but is also influenced by the type of bullet (i.e. hollow point rounds spread out causing temporary cavity damage) . Rifles of course, utilize the highest-velocity bullets making them the most potent type of firearm with regards to temporary cavity damage.

Ah, so a gun like an AR-15 has the best stopping power?

Well, no. Contrary to common belief, assault rifle ammunitions fall somewhere between pistol ammunition and full power rifle ammunition when it comes to stopping power. AR ammunitions are typically relatively high velocity rounds and are known to penetrate through tissue for several inches before yawing (veering from its line of flight). With the right aim, this can indeed be lethal. But with the wrong aim, the bullet will simply pass through with little tissue distortion. It’s because of this that most game departments forbid the use of AR’s on deer since it is not disruptive enough to consistently drop a deer in its tracks. Rifle rounds such as .30/06, .308, or 7.62 x 51 produce much more stopping power than an AR-15.

This of course begs the question – why does the military use a .223 AR round? The answer is simple – because soldiers can carry twice as many .223 rounds as an equivalent weight of a more effective rifle round such as a .308. Also, .223 rounds don’t produce as much rifle recoil which makes the gun more accurate to shoot in a fully automatic configuration (with a higher velocity round and thus a stronger recoil, the gun would bounce all over the place).

So with a high velocity rifle, a bullet will knock a person off their feet?

Shockwave created by "hydrostatic shock" or hydraulic shock"Sorry, but no. This is the single biggest myth perpetrated in the movies. A projectile striking a target will not register any greater push than the weapon’s recoil felt by the shooter (not taking into consideration recoil-reducing features such as gas ports). If a shot could indeed knock a person off their feet, the laws of physics (specifically, the law of conservation of momentum) say it would also knock the shooter off their feet. Still, a strong push (equal to the “kick” of the gun) will be felt by the target which could cause them to stumble. In addition, uncontrollable reflex reactions may make the target appear to be knocked off their feet. The projectile striking the target however, has nowhere near the force needed to lift a person off their feet.

Still, pain from a bullet wound surely causes a person to be pulled out of action?

Not necessarily. Most persons who have survived gunshot wounds say that at first, during the heat of action with adrenaline coursing through their veins, they were not even sure they had been shot (however, they do say that a few hours after being shot, the bullet wound feels like a hot iron was pressed through the flesh). Experienced police note that many times it takes several shots for a target to be brought down. Even hunters know that many times their prey do not fall on the first shot. Deer or other large game, even if shot in the heart, may run for 50 yards or more before falling. Given that human muscle density is practically identical to an animal’s, human reactions to gunshot wounds are no different. For humans, how they react to a gunshot wound is more a result of their preconceptions of how they’re supposed to act (e.g. fall down and scream) which in truth, is the most likely reason for most “one-shot stops”.

How to stop a human using a gun

Critical zones on the human body where shot should be placed for optimal stopping powerThere are only a few ways to incapacitate a person using a firearm. First, the gunshot wound must cause sufficient bleeding to cause them to lose blood and die. Rapid blood loss from a gunshot wound is the number one preventable cause of death on the battlefield. Due to a massive disruption of blood flow, shots to the heart will cause a person to bleed out and become incapacitated within 10 seconds. Other shots that sever brachial arteries in the arms or bilateral inguinal arteries in the groin will render a person incapacitated within minutes (this is the reason why aiming to shoot a person in the arms or legs to create a non-fatal “flesh wound” is a myth – major arteries in extremities still cause a person to bleed out quickly).  Regardless, the effect from blood loss, even from injuries to the heart, is not immediate.

There is only one way to instantly incapacitate a person using a gun – disruption of the brain or spinal cord.  Shots that hit the brain or sever the spinal cord will produce near instantaneous stoppage of the target. Of course, this is most easily obtained using a head shot, which requires expert shooting skills even at short distances.  Thus the only means to stop a person instantly via a firearm is quite difficult to achieve – or at least much more difficult than the movies make it seem.

There is a third type of gunshot wound, known as “tension pneumothorax” or more commonly, collapsed lung, that does not immediately render the enemy incapacitated but does produce death within minutes. Lungs have no muscles and mostly work due to negative pressure inside the chest. This means any type of hole in the chest is bad news. In such cases, a victim will die quickly unless the hole is plugged to prevent air from being sucked into the chest cavity (remarkably, any type of tape will work fine for plugging the hole). Any hole between the neck and the belly button is cause for concern.

Finally, if you are lucky, the gunshot can cause a condition known as “hydrostatic shock” or hydraulic shock”.  This occurs if the kinetic energy of the bullet sends a shock wave through the body, transferring physical shock to tissues whose physiologic function may be disrupted.  It’s rare but if it occurs, can produce incapacitation much quicker than blood loss effects.  Again though, it’s a rare phenomenon.

Conclusion – How to stop a person dead in their tracks with a firearm

In short, to stop a person with a gun, you have to not only use the right ammunition but also either (1) use perfect shot placement with one or two bullets to the head or (2) use many high-velocity bullets to the body.  For option 1 (a well placed shot) using a pistol, ammunition such as  9mm provides sufficient tissue penetration while reducing recoil allowing for perfect placement of the shot to the head.  For option 2 (many shots to the body with a large caliber bullet), the “big hole” school of thought says a .40 S&W pistol round will do the trick.  For either option (head or body), most any hunting rifle will produce the needed effect.

Regardless of your choice of weapon, keep in mind that despite what we see in the movies, it’s fairly difficult to stop a person dead in their tracks with a gun.

Bullet calibers and their velocity

Print Friendly, PDF & Email