Stopping power
Encyclopedia
Stopping power is a colloquial
term used to describe the ability of a firearm
or other weapon to cause a penetrating ballistic injury to a target, human or animal, sufficient to incapacitate the target where it stands.
The term is not a euphemism
for lethality
. It refers only to a weapon's ability to incapacitate quickly, regardless of whether death ultimately ensues. Some theories of stopping power involve concepts such as "energy
transfer" and "hydrostatic shock
", although there is disagreement regarding the importance of these effects.
Stopping power is related to the physical properties of the bullet and the effect it has on its target, but the issue is complicated and not easily studied. Critics contend that the importance of "one-shot stop" statistics is overstated, pointing out that most gun encounters do not involve a "shoot once and see how the target reacts" situation.
Stopping is usually caused not by the force of the bullet (especially in the case of handgun
and rifle
bullets), but by the damaging effects of the bullet, which are typically a loss of blood
, and with it, blood pressure
. More immediate effects can result when a bullet damages parts of the central nervous system
, such as the spine or brain. In response to addressing stopping power issues, the Mozambique Drill
was developed to maximize the likelihood of an attacker's quick incapacitation.
A manstopper is a generic term used to describe any combination of firearm
and ammunition
that can reliably incapacitate, or "stop", a human target immediately. For example, the .45 ACP
pistol
round and the .357 Magnum
revolver
round both have firm reputations as "manstoppers". Historically, one type of ammunition has had the specific tradename "Manstopper". Officially known as the Mk III cartridge
, these were made to suit the British Webley .455 service revolver
in the early 20th century. The ammunition used a 220 gr cylindrical bullet with hemispherical depressions at both ends. The front acted as a hollow point
deforming on impact while the base opened to seal the round in the barrel. It was introduced in 1898 for use against "savage
s", but fell quickly from favour due to concerns of breaching the Hague Convention's
international laws on military ammunition, and was replaced in 1900 by re-issued Mk II pointed-bullet ammunition.
Some sporting arms are also referred to as "stoppers" or "stopping rifles". These powerful arms are often used by game
hunters (or their guides) for stopping a suddenly charging creature, like a buffalo or an elephant
.
in the Philippines
, British
in New Zealand
) engaging in close action with native tribesmen found that their pistols were not able to stop charging warrior
s. This led to larger caliber weapons (such as the .45 Colt being returned to service, and the .45 ACP
being developed) intended to stop opponents with a single round. (See Knockback)
During the Seymour Expedition in China, at one of the battles at Langfang, Chinese Boxer
s armed with swords and spears charged the British and Americans, who were armed with guns. At point blank range, one British had to empty four bullets into a Boxer before he stopped, and the American Captain Bowman McCalla reported that single rifle shots were not enough, multiple rifle shots were needed to halt a Boxer. Only machine guns were effective in stopping the Boxers.
will destroy or damage any tissues
which it penetrates, creating a wound channel. It will also cause nearby tissue to stretch and expand as it passes through tissue. These two effects are typically referred to as permanent cavitation (the hole left by the bullet) and temporary cavitation (the tissue displaced as the bullet passed). These phenomena are unrelated to low-pressure cavitation
in liquids.
The degree to which permanent and temporary cavitation occur is dependent on the mass, diameter
, material, design and velocity
of the bullet. This is because bullets crush tissue, and do not cut it. A bullet constructed with a half diameter ogive
designed meplat
and hard, solid copper
alloy material will crush only the tissue directly in front of the bullet. This type of bullet (monolithic-solid rifle bullet) is conducive to cause more temporary cavitation as the tissue flows around the bullet, causing a deep and narrow wound channel. A bullet constructed with a two diameter, hollow point ogive
designed meplat and low-antimony
lead
-alloy core with a thin gilding metal jacket material will crush tissue in front and to the sides as the bullet expands. Due to the energy expended in bullet expansion, velocity is lost more quickly. This type of bullet (hollow-point hand gun bullet) is conducive to causing more permanent cavitation as the tissue is crushed and accelerated into other tissues by the bullet, causing a shorter and more voluminous wound channel.
Bullets are constructed to behave in different ways, depending on the intended target. Different bullets are constructed variously to: not expand upon impact, expand upon impact at high velocity, expand upon impact, expand across a broad range of velocities, expand upon impact at low velocity, tumble upon impact, fragment upon impact, or disintegrate upon impact.
To control the expansion of a bullet, meplat design and materials are engineered. The meplat designs are: flat; round to pointed depending on the ogive; hollow pointed which can be large in diameter and shallow or narrow in diameter and deep and truncated which is a long narrow punched hole in the end of a monolithic-solid type bullet. The materials used to make bullets are: pure lead; alloyed lead for hardness; gilding metal
jacket which is a copper alloy of nickel
and zinc
to promote higher velocities; pure copper; copper alloy of bronze
with tungsten
steel alloy inserts to promote weight.
Some bullets are constructed by bonding the lead core to the jacket to promote higher weight retention upon impact, causing a larger and deeper wound channel. Some bullets have a web in the center of the bullet to limit the expansion of the bullet while promoting penetration. Some bullets have dual cores to promote penetration.
Bullets that might be considered to have stopping power for dangerous large game animals are usually 11.63 mm (.458 caliber) and larger, including 12-gauge shotgun slugs. These bullets are monolithic-solids; full metal jacketed
and tungsten steel insert. They are constructed to hold up during close range, high velocity impacts. These bullets are expected to impact and penetrate, and transfer energy to the surrounding tissues and vital organs through the entire length of a game animal’s body if need be.
Bullets with sufficient stopping power for humans are generally large caliber, 9.07 mm (.357 caliber
) handgun bullets of hollow point design. Pre-fragmented bullets such as Glaser Safety Slug
s and MagSafe ammunition are designed to fragment into birdshot on impact with the target. This fragmentation is intended to create more trauma to the target, and also to reduce collateral damage caused from ricocheting or overpenetrating of the target and the surrounding environments such as walls. Fragmenting rounds have been shown to be unlikely to obtain deep penetration necessary to disrupt vital organs located at the back of a hostile human.
will cause loss of pumping efficiency, loss of blood, and eventual cardiac arrest
. A hole through the liver
or lung
will be similar, with the lung shot having the added effect of reducing blood oxygenation; these effects however are generally slower to arise than damage to the heart. A hole through the brain
can cause instant unconsciousness
and will likely kill the recipient. A hole through the spinal cord
will instantly interrupt the nerve signals to and from some or all extremities, disabling the target and in many cases also resulting in death (as the nerve signals to and from the heart and/or lungs are interrupted by a shot high in the chest or to the neck). By contrast, a hole through an arm or leg which hits only muscle
will cause a great deal of pain but is unlikely to be fatal, unless one of the large blood vessels (femoral
or brachial
arteries, for example) is also severed in the process.
The effects of temporary cavitation are less well understood, due to a lack of a test material identical to living tissue. Studies on the effects of bullets typically are based on experiments using ballistic gelatin
, in which temporary cavitation causes radial tears where the gelatin was stretched. Although such tears are visually engaging, some animal tissues (other than bone or liver) are more elastic
than gelatin. In most cases, temporary cavitation is unlikely to cause anything more than a bruise
. Some speculation states that nerve bundles
can be damaged by temporary cavitation, creating a stun effect, but this has not been confirmed.
One exception to this is when a very powerful temporary cavity intersects with the spine
. In this case, the resulting blunt trauma
can slam the vertebrae together hard enough to either sever the spinal cord, or damage it enough to knock out, stun, or paralyze the target. For instance, in the shootout between eight FBI
agents and two bank robbers on April 11, 1986 in Miami, Florida
, (see FBI Miami shootout, 1986
) Special Agent Gordon McNeill was struck in the neck by a high-velocity .223
bullet fired by Michael Platt. While the bullet did not directly contact the spine, and the wound incurred was not ultimately fatal, the temporary cavitation was sufficient to render SA McNeill paralyzed for several hours.
Temporary cavitation can also cause the tearing of tissues if a very large amount of force is involved. The tensile strength of muscle ranges roughly from 1 to 4 MPa (145 to 580 lbf/in2), and minimal damage will result if the pressure exerted by the temporary cavitation is below this. Gelatin and other less elastic media have much lower tensile strengths, thus they exhibit more damage after being struck with the same amount of force. At typical handgun velocities, bullets will create temporary cavities with much less than 1 MPa of pressure, and thus are incapable of causing damage to elastic tissues which they do not directly contact.
Core-locked rifle bullets that strike a major bone (such as a femur) can expend their entire energy into the surrounding tissue, causing it to take on a gelled consistency as the cellular structure is destroyed. The struck bone is commonly shattered at the point of impact.
High velocity fragmentation can also increase the effect of temporary cavitation. The fragments sheared from the bullet cause many small permanent cavities around the main entry point. The main mass of the bullet can then cause a truly massive amount of tearing as the perforated tissue is stretched.
Whether a person or animal will be incapacitated (i.e. "stopped") when shot depends on a large number of factors including physical, physiological, and psychological effects.
(CNS) to the point of paralysis, unconsciousness, or death. Bullets can achieve this directly or indirectly. If a bullet causes sufficient damage to the brain
or spinal cord
, immediate loss of consciousness or paralysis, respectively, can result. However, these targets are relatively small and mobile, making them extremely difficult to hit even under optimal circumstances.
Bullets can indirectly disrupt the CNS by damaging the cardiovascular system so that it can no longer provide enough oxygen to the brain to sustain consciousness. This can be the result of bleeding
from a perforation of a large blood vessel or blood-bearing organ, or the result of damage to the lungs or airway. If blood flow is completely cut off from the brain, a human still has enough oxygenated blood in their brain for 10–15 seconds of wilful action, though with rapidly decreasing effectiveness as the victim begins to lose consciousness.
Unless a bullet directly damages or disrupts the central nervous system, a person or animal will not be instantly and completely incapacitated by physiological damage. However, bullets can cause other disabling injuries that prevent specific actions (a person shot in the femur cannot walk) and the physiological pain response from severe injuries will temporarily disable most individuals.
Several scientific papers reveal ballistic pressure wave effects on wounding and incapacitation, including central nervous system injuries from hits to the thorax and extremities. These papers document remote wounding effects for both rifle and pistol levels of energy transfer.
Recent work by Courtney and Courtney provides compelling support for the role of a ballistic pressure wave in creating remote neural effects leading to incapacitation and injury. This work builds upon the earlier works of Suneson et al. where the researchers implanted high-speed pressure transducers into the brain of pigs and demonstrated that a significant pressure wave reaches the brain of pigs shot in the thigh. These scientists observed neural damage in the brain caused by the distant effects of the ballistic pressure wave originating in the thigh. The results of Suneson et al. were confirmed and expanded upon by a later experiment in dogs which "confirmed that distant effect exists in the central nervous system after a high-energy missile impact to an extremity. A high-frequency oscillating pressure wave with large amplitude and short duration was found in the brain after the extremity impact of a high-energy missile ..." Wang et al. observed significant damage in both the hypothalamus and hippocampus regions of the brain due to remote effects of the ballistic pressure wave.
, surrender, or flee when shot or shot at. Emotional fainting is the likely reason for most "one-shot stops", and not an intrinsic effectiveness quality of any firearm or bullet; there are many documented instances where people have instantly dropped unconscious when the bullet only hit an extremity, or even completely missed. Additionally, the muzzle blast and flash from many firearms are substantial and can cause disorientation, dazzling, and stunning effects. Flashbangs (stun grenades) and other less-lethal "distraction devices" rely exclusively on these effects.
Pain
is another psychological factor, and can be enough to dissuade a person from continuing their actions.
Temporary cavitation can emphasize the impact of a bullet, since the resulting tissue compression is identical to simple blunt force trauma. It is easier for someone to feel when they have been shot if there is considerable temporary cavitation, and this can contribute to either psychological factor of incapacitation.
However, if a person is sufficiently enraged
, determined, or intoxicated they can simply shrug off the psychological effects of being shot. Therefore, such effects are not as reliable as physiological effects at stopping people. Animals will not faint or surrender if injured, though they may become frightened by the loud noise and pain of being shot, so psychological mechanisms are generally less effective against non-humans.
and the International Wound Ballistics Association (IWBA), between 12.5 and 14 inches (318 and 356 mm) of penetration in calibrated tissue simulant is optimal performance for a bullet which is meant to be used defensively, against a human adversary. They also believe that penetration is one of the most important factors when choosing a bullet (and that the number one factor is shot placement). If the bullet penetrates less than their guidelines, it is inadequate, and if it penetrates more, it is still satisfactory though not optimal. The FBI's penetration requirement is very similar at 12 to 18 inches (305 to 457 mm).
A penetration depth of 12.5 to 14 inches (318 and 356 mm) may seem excessive, but a bullet sheds velocity—and crushes a narrower hole—as it penetrates deeper, while losing velocity, so the bullet might be crushing a very small amount of tissue (simulating an "ice pick" injury) during its last two or three inches of travel, giving only between 9.5 and 12 inches of effective wide-area penetration. Also, skin is elastic and tough enough to cause a bullet to be retained in the body, even if the bullet had a relatively high velocity when it hit the skin. About 250 ft/s (76 m/s) velocity is required for an expanded hollow point bullet to puncture skin 50% of the time.
The IWBA's and FBI's penetration guidelines are to ensure that the bullet can reach a vital structure from most angles, while retaining enough velocity to generate a large diameter hole through tissue. An extreme example where penetration would be important is if the bullet first had to enter and then exit an outstretched arm before impacting the torso. A bullet with low penetration might embed itself in the arm whereas a higher penetrating bullet would penetrate the arm then enter the thorax where it would have a chance of hitting a vital organ.
that is transferred to the target, the greater the destructive potential.
Energy is a function of mass and the square of velocity. Generally speaking, it is the intention of the shooter to deliver an adequate amount of energy to the target via the projectile/s. Projectiles such as rifle bullets, high velocity handgun bullets and shotgun slugs can over-penetrate. Projectiles such as handgun bullets and shot can under-penetrate. Projectiles that reach the target with too low a velocity or bird shot may not penetrate at all. All the above conditions affect energy transfer.
Over-penetration is detrimental to stopping power in regards to energy. This is because a bullet that passes through the target does not transfer all of its energy to the target. Despite decreased tissue damage due to loss of transferred energy on an over-penetrating shot, the resulting exit wound would cause increased blood loss and therefore a decrease in blood pressure in the victim. This effect on both persons and game animals is likely to be incapacitating over the length of the entire shooting event.
Under-penetration is also detrimental to stopping power. Projectile/s that do not transfer enough energy to the target may fail to create a fatal wound cavity. Also vital organs may not be reached, thereby limiting the amount of tissue damage, blood loss, and/or loss of blood pressure.
Non-penetration of projectile/s may only deliver enough energy to create bruising, punctures and or blunt force trauma. All of which may result in internal injury solely through the force of the impact but not stop the target. A notable example of projectiles designed to deliver stopping power without target penetration are Flexible baton round
s (commonly known as "beanbag bullets"), a type of reduced-lethality ammunition.
As mentioned above, there are many factors that affect "stopping power." Within this theory energy transfer is related to destructive potential; however, the importance of energy transfer in determining the stopping power of projectiles (when compared to other factors like location of the wound and wound cavity size) is a controversial topic.
The force exerted by a projectile upon tissue is equal to the bullet's local rate of kinetic energy loss, with distance
(the first derivative of the bullets kinetic energy with respect to position). The ballistic pressure wave is proportional to this retarding force (Courtney and Courtney), and this retarding force is also the origin of both temporary cavitation and prompt damage (CE Peters).
is a theory of terminal ballistics
that wounding effects are created by a shock wave in the tissues of the target. It is argued that evidence of such shock can be seen in ultra-high-speed images of supersonic bullets passing through various objects such as fruit; the fruit explodes due to the shock waves caused by the bullet passing through at high speed. Proponents of the theory contend that damage to the brain from hydrostatic shock from a shot to the chest occurs in humans with most rifle cartridges and some higher-velocity handgun cartridges.
caliber revolvers carried by U.S. and British soldiers were incapable of bringing down a charging warrior. Thus, in the early 1900s, the U.S. reverted to the .45 Colt in single action revolvers, and later adopted the .45 ACP
cartridge in what was to become the M1911A1 pistol and the British adopted the .455 Webley
caliber cartridge in the Webley Revolver
. The larger cartridges were chosen largely due to the Big Hole Theory (a larger hole does more damage), but the common interpretation was that these were changes from a light, deeply penetrating bullet to a larger, heavier "manstopper" bullet.
Though popularized in television and movies, and commonly referred to as "true stopping power" by novice or uneducated proponents of large powerful calibers such as .44 Magnum
, the effect of knockback from a handgun and indeed most personal weapons is largely a myth. The momentum
of the so-called "manstopper" .45 ACP
bullet is approximately that of a 1 pound (0.45359237 kg) mass dropped from a height of 11.4 feet (3.5 m).It should be noted that momentum is very different from kinetic energy
; an equivalent kinetic energy [855 ft·lbf (1159 J)] of a typical .45 ACP bullet is that of a 60 pound (27 kilogram) mass dropped from a height of 14 feet (4.3 meters). Such a force is simply incapable of arresting a running target's forward momentum. In addition, bullets are designed to penetrate instead of strike a blunt force blow, because, in penetrating, more severe tissue damage is done. A bullet with sufficient energy to knock down an assailant, such as a high-speed rifle bullet, would be more likely to instead pass straight through, while not transferring the full energy (in fact only a very small percentage of the full energy) of the bullet to the victim.
The "knockback" effect is however commonly "seen" in real-life shootings, and can be explained by physiological and psychological means. Humans encountering a physical hit, be it a punch or a bullet, are conditioned to absorb the blow by moving in the same direction as the force. The physical effect against a non-penetrating weapon is to reduce the force felt by the blow, and in addition, retreating from an attack increases the distance such an attack must cover, which in the case of non-projectile weapons such as fists or a knife, places the target out of range of further attack. In addition, there is a theoretical sociological explanation, that in modern civilization, with far greater separation by most individuals from violence, hunting, and combat, normal individuals may simply recoil, buckle, or fall backward when hit by a bullet, even when in pure physiological terms they are perfectly capable of continuing to charge.
Although knockback is not possible with a handgun bullet, it can be an actual effect occurring in reaction to being hit by a massive slug, such as a rubber bullet or sandbag fired from a shotgun
. The dynamics of a slug round are quite different than penetrating bullets; the projectile is here designed not to penetrate but instead to strike a hard, blunt force blow, and as the momentum carried by a shotgun cartridge is greater than practically any production handgun cartridge, the force imparted is comparable to a hard punch and is capable, by physics, of affecting a person's forward motion. In any case, due to conservation of momentum, the gun's recoil is always larger than the bullet's knockback, as some momentum of the bullet is lost during flight, and if the bullet penetrates through the target it will not have imparted all its momentum into the target.
Some argue that this hypothesis ignores any inherent selection bias
. For example, high-velocity 9 mm hollow point
rounds appear to have the highest percentage of one-shot stops. Rather than identifying this as an inherent property of the firearm/bullet combination, the situations where these have occurred need to be considered. The 9 mm has been the predominantly used caliber of many police departments, so many of these one-shot-stops were probably made by well-trained police officers, where accurate placement would be a contributory factor. However, Marshall's database of "one-shot-stops" does include shootings from law enforcement agencies, private citizens, and criminals alike.
Critics of this theory point out that bullet placement is a very significant factor, but is only generally used in such one-shot-stop calculations, covering shots to the torso.
Since 2006, after the conviction of retired school teacher Harold Fish in Arizona for second degree murder during a self-defense shooting, some CCW
holders in the United States have elected to switch from carrying hollow-point bullets, and especially 10mm Auto caliber weapons with perceived higher one-shot stopping power, to carrying smaller caliber weapons. Fish's conviction for killing a homeless man with a history of dangerous violent behavior and mental instability who attacked Fish while hiking on a remote trail, was obtained through a jury trial by stressing that Fish overreacted, through choosing to use the increased stopping power of 10 mm hollow point
bullets. State law in Arizona has subsequently been changed, such that the state now has the burden to prove that a self defense shooting was not in self defense, whereas the burden previously, before the Fish incident, was that the shooter on trial had to prove that the shooting was in fact, done in self defense. The conviction has since been thrown out by the Arizona Court of Appeals. CCW training classes often advise the use of bullets that are identical to those used by local police, in type (FMJ or hollow point) and caliber, to prevent an overreaction prosecution.
round, arguing that it has a better ballistic profile than the .45, and more stopping power than a 9×19mm Parabellum.
The theory centers on the "permanent cavitation" element of a handgun wound. A big hole damages more tissue. It is therefore valid to a point, but penetration is also important, as a large bullet that does not penetrate will be less likely to strike vital blood vessels and blood-carrying organs such as the heart and liver, while a smaller bullet that penetrates deep enough to strike these organs or vessels will cause faster bleed-out through a smaller hole. The ideal may therefore be a combination; a large bullet that penetrates deeply, which can be achieved with a larger, slower non-expanding bullet, or a smaller, faster expanding bullet such as a hollow point.
In the extreme a heavier bullet (which preserves momentum greater than a lighter bullet of the same caliber) may "overpenetrate", passing completely through the target without expending all of its kinetic energy. So-called "overpenetration" is not an important consideration when it comes to wounding incapacitation or "stopping power", because: (a) while a lower proportion of the bullet's energy is transferred to the target a higher absolute amount of energy is shed than in partial penetration, and (b) overpenetration creates an exit wound.
, mental illness
, motivation levels, body part strike (e.g. "armpit hold") which may determine which round will kill or at least catastrophically affect a target during any given situation.
Colloquialism
A colloquialism is a word or phrase that is common in everyday, unconstrained conversation rather than in formal speech, academic writing, or paralinguistics. Dictionaries often display colloquial words and phrases with the abbreviation colloq. as an identifier...
term used to describe the ability of a firearm
Firearm
A firearm is a weapon that launches one, or many, projectile at high velocity through confined burning of a propellant. This subsonic burning process is technically known as deflagration, as opposed to supersonic combustion known as a detonation. In older firearms, the propellant was typically...
or other weapon to cause a penetrating ballistic injury to a target, human or animal, sufficient to incapacitate the target where it stands.
The term is not a euphemism
Euphemism
A euphemism is the substitution of a mild, inoffensive, relatively uncontroversial phrase for another more frank expression that might offend or otherwise suggest something unpleasant to the audience...
for lethality
Lethality
Lethality is a term designating the ability of a weapon to kill. Most often this term is used when referring to chemical weapons, biological weapons, or their chemical components. The use of this term denotes the ability of these weapons to kill, but also the possibility that they may not kill...
. It refers only to a weapon's ability to incapacitate quickly, regardless of whether death ultimately ensues. Some theories of stopping power involve concepts such as "energy
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
transfer" and "hydrostatic shock
Hydrostatic shock
Hydrostatic shock or hydraulic shock describes the observation that a penetrating projectile can produce remote wounding and incapacitating effects in living targets through a hydraulic effect in their liquid-filled tissues, in addition to local effects in tissue caused by direct impact...
", although there is disagreement regarding the importance of these effects.
Stopping power is related to the physical properties of the bullet and the effect it has on its target, but the issue is complicated and not easily studied. Critics contend that the importance of "one-shot stop" statistics is overstated, pointing out that most gun encounters do not involve a "shoot once and see how the target reacts" situation.
Stopping is usually caused not by the force of the bullet (especially in the case of handgun
Handgun
A handgun is a firearm designed to be held and operated by one hand. This characteristic differentiates handguns as a general class of firearms from long guns such as rifles and shotguns ....
and rifle
Rifle
A rifle is a firearm designed to be fired from the shoulder, with a barrel that has a helical groove or pattern of grooves cut into the barrel walls. The raised areas of the rifling are called "lands," which make contact with the projectile , imparting spin around an axis corresponding to the...
bullets), but by the damaging effects of the bullet, which are typically a loss of blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
, and with it, blood pressure
Blood pressure
Blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, BP varies...
. More immediate effects can result when a bullet damages parts of the central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
, such as the spine or brain. In response to addressing stopping power issues, the Mozambique Drill
Mozambique Drill
The Mozambique Drill, also known as the Failure to Stop Drill, or Failure Drill, is a close-quarter shooting technique in which the shooter fires twice into the torso of a target , momentarily assesses the hits, then follows them up with a carefully aimed shot to the head of the target.The third...
was developed to maximize the likelihood of an attacker's quick incapacitation.
A manstopper is a generic term used to describe any combination of firearm
Firearm
A firearm is a weapon that launches one, or many, projectile at high velocity through confined burning of a propellant. This subsonic burning process is technically known as deflagration, as opposed to supersonic combustion known as a detonation. In older firearms, the propellant was typically...
and ammunition
Ammunition
Ammunition is a generic term derived from the French language la munition which embraced all material used for war , but which in time came to refer specifically to gunpowder and artillery. The collective term for all types of ammunition is munitions...
that can reliably incapacitate, or "stop", a human target immediately. For example, the .45 ACP
.45 ACP
The .45 ACP , also known as the .45 Auto by C.I.P., is a cartridge designed by John Browning in 1904, for use in his prototype Colt semi-automatic .45 pistol and eventually the M1911 pistol adopted by the United States Army in 1911.-Design and history:The U.S...
pistol
Pistol
When distinguished as a subset of handguns, a pistol is a handgun with a chamber that is integral with the barrel, as opposed to a revolver, wherein the chamber is separate from the barrel as a revolving cylinder. Typically, pistols have an effective range of about 100 feet.-History:The pistol...
round and the .357 Magnum
.357 Magnum
The .357 S&W Magnum , or simply .357 Magnum, is a revolver cartridge created by Elmer Keith, Phillip B. Sharpe, Colonel D. B. Wesson of firearms manufacturer Smith & Wesson, and Winchester. It is based upon Smith & Wesson's earlier .38 Special cartridge. The .357 Magnum cartridge was introduced in...
revolver
Revolver
A revolver is a repeating firearm that has a cylinder containing multiple chambers and at least one barrel for firing. The first revolver ever made was built by Elisha Collier in 1818. The percussion cap revolver was invented by Samuel Colt in 1836. This weapon became known as the Colt Paterson...
round both have firm reputations as "manstoppers". Historically, one type of ammunition has had the specific tradename "Manstopper". Officially known as the Mk III cartridge
.455 Webley
.455 Webley is a British handgun cartridge, most commonly used in the Webley top break revolvers Marks I through VI.The .455 cartridge was a service revolver cartridge, featuring a rimmed cartridge firing a .45 bullet at the relatively low velocity of 650 ft/s...
, these were made to suit the British Webley .455 service revolver
Webley Revolver
The Webley Revolver was, in various marks, the standard issue service pistol for the armed forces of the United Kingdom, the British Empire, and the Commonwealths from 1887 until 1963.The Webley is a top-break revolver with automatic extraction...
in the early 20th century. The ammunition used a 220 gr cylindrical bullet with hemispherical depressions at both ends. The front acted as a hollow point
Hollow point bullet
A hollow point is an expanding bullet that has a pit or hollowed out shape in its tip, generally intended to cause the bullet to thin upon entering a target in order to decrease penetration and disrupt more tissue as it travels through the target. It is also used for controlled penetration, where...
deforming on impact while the base opened to seal the round in the barrel. It was introduced in 1898 for use against "savage
Barbarian
Barbarian and savage are terms used to refer to a person who is perceived to be uncivilized. The word is often used either in a general reference to a member of a nation or ethnos, typically a tribal society as seen by an urban civilization either viewed as inferior, or admired as a noble savage...
s", but fell quickly from favour due to concerns of breaching the Hague Convention's
Hague Conventions (1899 and 1907)
The Hague Conventions were two international treaties negotiated at international peace conferences at The Hague in the Netherlands: The First Hague Conference in 1899 and the Second Hague Conference in 1907...
international laws on military ammunition, and was replaced in 1900 by re-issued Mk II pointed-bullet ammunition.
Some sporting arms are also referred to as "stoppers" or "stopping rifles". These powerful arms are often used by game
Game (food)
Game is any animal hunted for food or not normally domesticated. Game animals are also hunted for sport.The type and range of animals hunted for food varies in different parts of the world. This will be influenced by climate, animal diversity, local taste and locally accepted view about what can or...
hunters (or their guides) for stopping a suddenly charging creature, like a buffalo or an elephant
Elephant
Elephants are large land mammals in two extant genera of the family Elephantidae: Elephas and Loxodonta, with the third genus Mammuthus extinct...
.
History
The concept of "stopping power" appeared in the late 19th Century when colonial troops (AmericanUnited States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
in the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
, British
British Empire
The British Empire comprised the dominions, colonies, protectorates, mandates and other territories ruled or administered by the United Kingdom. It originated with the overseas colonies and trading posts established by England in the late 16th and early 17th centuries. At its height, it was the...
in New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
) engaging in close action with native tribesmen found that their pistols were not able to stop charging warrior
Warrior
A warrior is a person skilled in combat or warfare, especially within the context of a tribal or clan-based society that recognizes a separate warrior class.-Warrior classes in tribal culture:...
s. This led to larger caliber weapons (such as the .45 Colt being returned to service, and the .45 ACP
.45 ACP
The .45 ACP , also known as the .45 Auto by C.I.P., is a cartridge designed by John Browning in 1904, for use in his prototype Colt semi-automatic .45 pistol and eventually the M1911 pistol adopted by the United States Army in 1911.-Design and history:The U.S...
being developed) intended to stop opponents with a single round. (See Knockback)
During the Seymour Expedition in China, at one of the battles at Langfang, Chinese Boxer
Boxer Rebellion
The Boxer Rebellion, also called the Boxer Uprising by some historians or the Righteous Harmony Society Movement in northern China, was a proto-nationalist movement by the "Righteous Harmony Society" , or "Righteous Fists of Harmony" or "Society of Righteous and Harmonious Fists" , in China between...
s armed with swords and spears charged the British and Americans, who were armed with guns. At point blank range, one British had to empty four bullets into a Boxer before he stopped, and the American Captain Bowman McCalla reported that single rifle shots were not enough, multiple rifle shots were needed to halt a Boxer. Only machine guns were effective in stopping the Boxers.
Dynamics of bullets
A bulletBullet
A bullet is a projectile propelled by a firearm, sling, or air gun. Bullets do not normally contain explosives, but damage the intended target by impact and penetration...
will destroy or damage any tissues
Tissue (biology)
Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...
which it penetrates, creating a wound channel. It will also cause nearby tissue to stretch and expand as it passes through tissue. These two effects are typically referred to as permanent cavitation (the hole left by the bullet) and temporary cavitation (the tissue displaced as the bullet passed). These phenomena are unrelated to low-pressure cavitation
Cavitation
Cavitation is the formation and then immediate implosion of cavities in a liquidi.e. small liquid-free zones that are the consequence of forces acting upon the liquid...
in liquids.
The degree to which permanent and temporary cavitation occur is dependent on the mass, diameter
Diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...
, material, design and velocity
Velocity
In physics, velocity is speed in a given direction. Speed describes only how fast an object is moving, whereas velocity gives both the speed and direction of the object's motion. To have a constant velocity, an object must have a constant speed and motion in a constant direction. Constant ...
of the bullet. This is because bullets crush tissue, and do not cut it. A bullet constructed with a half diameter ogive
Ogive
An ogive is the roundly tapered end of a two-dimensional or three-dimensional object.-Applied physical science and engineering:In ballistics or aerodynamics, an ogive is a pointed, curved surface mainly used to form the approximately streamlined nose of a bullet or other projectile.The traditional...
designed meplat
Meplat
Meplat, from a French term for a flat surface, is the technical term for the tip or nose of a bullet. The shape of the meplat is important when determining how the bullet will move through the air. If uneven, the bullet will not have an ideal flight characteristic and will most likely not be of the...
and hard, solid copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
alloy material will crush only the tissue directly in front of the bullet. This type of bullet (monolithic-solid rifle bullet) is conducive to cause more temporary cavitation as the tissue flows around the bullet, causing a deep and narrow wound channel. A bullet constructed with a two diameter, hollow point ogive
Ogive
An ogive is the roundly tapered end of a two-dimensional or three-dimensional object.-Applied physical science and engineering:In ballistics or aerodynamics, an ogive is a pointed, curved surface mainly used to form the approximately streamlined nose of a bullet or other projectile.The traditional...
designed meplat and low-antimony
Antimony
Antimony is a toxic chemical element with the symbol Sb and an atomic number of 51. A lustrous grey metalloid, it is found in nature mainly as the sulfide mineral stibnite...
lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
-alloy core with a thin gilding metal jacket material will crush tissue in front and to the sides as the bullet expands. Due to the energy expended in bullet expansion, velocity is lost more quickly. This type of bullet (hollow-point hand gun bullet) is conducive to causing more permanent cavitation as the tissue is crushed and accelerated into other tissues by the bullet, causing a shorter and more voluminous wound channel.
Bullets are constructed to behave in different ways, depending on the intended target. Different bullets are constructed variously to: not expand upon impact, expand upon impact at high velocity, expand upon impact, expand across a broad range of velocities, expand upon impact at low velocity, tumble upon impact, fragment upon impact, or disintegrate upon impact.
To control the expansion of a bullet, meplat design and materials are engineered. The meplat designs are: flat; round to pointed depending on the ogive; hollow pointed which can be large in diameter and shallow or narrow in diameter and deep and truncated which is a long narrow punched hole in the end of a monolithic-solid type bullet. The materials used to make bullets are: pure lead; alloyed lead for hardness; gilding metal
Gilding metal
Gilding metal is a copper alloy, comprising 95% copper and 5% zinc. Technically, it is a brass.Gilding metal is used for various purposes, including the jackets of bullets, driving bands on some artillery shells, as well as enameled badges and other jewellery....
jacket which is a copper alloy of nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
and zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
to promote higher velocities; pure copper; copper alloy of bronze
Bronze
Bronze is a metal alloy consisting primarily of copper, usually with tin as the main additive. It is hard and brittle, and it was particularly significant in antiquity, so much so that the Bronze Age was named after the metal...
with tungsten
Tungsten
Tungsten , also known as wolfram , is a chemical element with the chemical symbol W and atomic number 74.A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as...
steel alloy inserts to promote weight.
Some bullets are constructed by bonding the lead core to the jacket to promote higher weight retention upon impact, causing a larger and deeper wound channel. Some bullets have a web in the center of the bullet to limit the expansion of the bullet while promoting penetration. Some bullets have dual cores to promote penetration.
Bullets that might be considered to have stopping power for dangerous large game animals are usually 11.63 mm (.458 caliber) and larger, including 12-gauge shotgun slugs. These bullets are monolithic-solids; full metal jacketed
Full metal jacket bullet
A full metal jacket is a bullet consisting of a soft core encased in a shell of harder metal, such as gilding metal, cupronickel or less commonly a steel alloy. This shell can extend around all of the bullet, or often just the front and sides with the rear left as exposed lead...
and tungsten steel insert. They are constructed to hold up during close range, high velocity impacts. These bullets are expected to impact and penetrate, and transfer energy to the surrounding tissues and vital organs through the entire length of a game animal’s body if need be.
Bullets with sufficient stopping power for humans are generally large caliber, 9.07 mm (.357 caliber
Caliber
In guns including firearms, caliber or calibre is the approximate internal diameter of the barrel in relation to the diameter of the projectile used in it....
) handgun bullets of hollow point design. Pre-fragmented bullets such as Glaser Safety Slug
Glaser Safety Slug
Glaser Safety Slug is a frangible bullet made by Glaser Safety Slug, Inc., a small American ammunition company based in Sturgis, South Dakota . The company was founded in 1975 by Armin Glaser the same year as the Glaser Safety Slug was developed by Jack Canon.-History:The original round was a...
s and MagSafe ammunition are designed to fragment into birdshot on impact with the target. This fragmentation is intended to create more trauma to the target, and also to reduce collateral damage caused from ricocheting or overpenetrating of the target and the surrounding environments such as walls. Fragmenting rounds have been shown to be unlikely to obtain deep penetration necessary to disrupt vital organs located at the back of a hostile human.
Physical
Permanent and temporary cavitation cause very different biological effects. The effects of a permanent cavity are fairly obvious. A hole through the heartHeart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
will cause loss of pumping efficiency, loss of blood, and eventual cardiac arrest
Cardiac arrest
Cardiac arrest, is the cessation of normal circulation of the blood due to failure of the heart to contract effectively...
. A hole through the liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
or lung
Lung
The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...
will be similar, with the lung shot having the added effect of reducing blood oxygenation; these effects however are generally slower to arise than damage to the heart. A hole through the brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
can cause instant unconsciousness
Unconsciousness
Unconsciousness is the condition of being not conscious—in a mental state that involves complete or near-complete lack of responsiveness to people and other environmental stimuli. Being in a comatose state or coma is a type of unconsciousness. Fainting due to a drop in blood pressure and a...
and will likely kill the recipient. A hole through the spinal cord
Spinal cord
The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...
will instantly interrupt the nerve signals to and from some or all extremities, disabling the target and in many cases also resulting in death (as the nerve signals to and from the heart and/or lungs are interrupted by a shot high in the chest or to the neck). By contrast, a hole through an arm or leg which hits only muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
will cause a great deal of pain but is unlikely to be fatal, unless one of the large blood vessels (femoral
Femoral artery
The femoral artery is a general term comprising a few large arteries in the thigh. They begin at the inguinal ligament and end just above the knee at adductor canal or Hunter's canal traversing the extent of the femur bone....
or brachial
Brachial artery
The brachial artery is the major blood vessel of the arm.It is the continuation of the axillary artery beyond the lower margin of teres major muscle. It continues down the ventral surface of the arm until it reaches the cubital fossa at the elbow. It then divides into the radial and ulnar arteries...
arteries, for example) is also severed in the process.
The effects of temporary cavitation are less well understood, due to a lack of a test material identical to living tissue. Studies on the effects of bullets typically are based on experiments using ballistic gelatin
Ballistic gelatin
Ballistic Gelatin is a testing medium scientifically correlated to swine muscle tissue , in which the effects of bullet wounds can be simulated. It was developed and improved by Martin Fackler and others in the field of wound ballistics. Ballistic gelatin is a solution of gelatin powder in water...
, in which temporary cavitation causes radial tears where the gelatin was stretched. Although such tears are visually engaging, some animal tissues (other than bone or liver) are more elastic
Elasticity (physics)
In physics, elasticity is the physical property of a material that returns to its original shape after the stress that made it deform or distort is removed. The relative amount of deformation is called the strain....
than gelatin. In most cases, temporary cavitation is unlikely to cause anything more than a bruise
Bruise
A bruise, also called a contusion, is a type of relatively minor hematoma of tissue in which capillaries and sometimes venules are damaged by trauma, allowing blood to seep into the surrounding interstitial tissues. Bruises can involve capillaries at the level of skin, subcutaneous tissue, muscle,...
. Some speculation states that nerve bundles
Nerve
A peripheral nerve, or simply nerve, is an enclosed, cable-like bundle of peripheral axons . A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons. Nerves are found only in the peripheral nervous system...
can be damaged by temporary cavitation, creating a stun effect, but this has not been confirmed.
One exception to this is when a very powerful temporary cavity intersects with the spine
Vertebral column
In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...
. In this case, the resulting blunt trauma
Physical trauma
Trauma refers to "a body wound or shock produced by sudden physical injury, as from violence or accident." It can also be described as "a physical wound or injury, such as a fracture or blow." Major trauma can result in secondary complications such as circulatory shock, respiratory failure and death...
can slam the vertebrae together hard enough to either sever the spinal cord, or damage it enough to knock out, stun, or paralyze the target. For instance, in the shootout between eight FBI
Federal Bureau of Investigation
The Federal Bureau of Investigation is an agency of the United States Department of Justice that serves as both a federal criminal investigative body and an internal intelligence agency . The FBI has investigative jurisdiction over violations of more than 200 categories of federal crime...
agents and two bank robbers on April 11, 1986 in Miami, Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
, (see FBI Miami shootout, 1986
FBI Miami shootout, 1986
The 1986 FBI Miami shootout was a gun battle that occurred on April 11, 1986 in an unincorporated region of Miami-Dade County in south Florida between eight Federal Bureau of Investigation agents and two serial bank robbers. During the firefight, Special Agents Jerry L. Dove and Benjamin P. Grogan...
) Special Agent Gordon McNeill was struck in the neck by a high-velocity .223
.223 Remington
The .223 Remington is a sporting cartridge with almost the same external dimensions as the 5.56×45mm NATO military cartridge. The name is commonly pronounced either two-two-three or two-twenty-three. It is loaded with a diameter, jacketed bullet, with weights ranging from , though the most common...
bullet fired by Michael Platt. While the bullet did not directly contact the spine, and the wound incurred was not ultimately fatal, the temporary cavitation was sufficient to render SA McNeill paralyzed for several hours.
Temporary cavitation can also cause the tearing of tissues if a very large amount of force is involved. The tensile strength of muscle ranges roughly from 1 to 4 MPa (145 to 580 lbf/in2), and minimal damage will result if the pressure exerted by the temporary cavitation is below this. Gelatin and other less elastic media have much lower tensile strengths, thus they exhibit more damage after being struck with the same amount of force. At typical handgun velocities, bullets will create temporary cavities with much less than 1 MPa of pressure, and thus are incapable of causing damage to elastic tissues which they do not directly contact.
Core-locked rifle bullets that strike a major bone (such as a femur) can expend their entire energy into the surrounding tissue, causing it to take on a gelled consistency as the cellular structure is destroyed. The struck bone is commonly shattered at the point of impact.
High velocity fragmentation can also increase the effect of temporary cavitation. The fragments sheared from the bullet cause many small permanent cavities around the main entry point. The main mass of the bullet can then cause a truly massive amount of tearing as the perforated tissue is stretched.
Whether a person or animal will be incapacitated (i.e. "stopped") when shot depends on a large number of factors including physical, physiological, and psychological effects.
Neurological
The only way to immediately incapacitate a person or animal is to damage or disrupt their central nervous systemCentral nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
(CNS) to the point of paralysis, unconsciousness, or death. Bullets can achieve this directly or indirectly. If a bullet causes sufficient damage to the brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
or spinal cord
Spinal cord
The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...
, immediate loss of consciousness or paralysis, respectively, can result. However, these targets are relatively small and mobile, making them extremely difficult to hit even under optimal circumstances.
Bullets can indirectly disrupt the CNS by damaging the cardiovascular system so that it can no longer provide enough oxygen to the brain to sustain consciousness. This can be the result of bleeding
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
from a perforation of a large blood vessel or blood-bearing organ, or the result of damage to the lungs or airway. If blood flow is completely cut off from the brain, a human still has enough oxygenated blood in their brain for 10–15 seconds of wilful action, though with rapidly decreasing effectiveness as the victim begins to lose consciousness.
Unless a bullet directly damages or disrupts the central nervous system, a person or animal will not be instantly and completely incapacitated by physiological damage. However, bullets can cause other disabling injuries that prevent specific actions (a person shot in the femur cannot walk) and the physiological pain response from severe injuries will temporarily disable most individuals.
Several scientific papers reveal ballistic pressure wave effects on wounding and incapacitation, including central nervous system injuries from hits to the thorax and extremities. These papers document remote wounding effects for both rifle and pistol levels of energy transfer.
Recent work by Courtney and Courtney provides compelling support for the role of a ballistic pressure wave in creating remote neural effects leading to incapacitation and injury. This work builds upon the earlier works of Suneson et al. where the researchers implanted high-speed pressure transducers into the brain of pigs and demonstrated that a significant pressure wave reaches the brain of pigs shot in the thigh. These scientists observed neural damage in the brain caused by the distant effects of the ballistic pressure wave originating in the thigh. The results of Suneson et al. were confirmed and expanded upon by a later experiment in dogs which "confirmed that distant effect exists in the central nervous system after a high-energy missile impact to an extremity. A high-frequency oscillating pressure wave with large amplitude and short duration was found in the brain after the extremity impact of a high-energy missile ..." Wang et al. observed significant damage in both the hypothalamus and hippocampus regions of the brain due to remote effects of the ballistic pressure wave.
Psychological
Emotional shock, terror, or surprise can cause a person to faintSyncope (medicine)
Syncope , the medical term for fainting, is precisely defined as a transient loss of consciousness and postural tone characterized by rapid onset, short duration, and spontaneous recovery due to global cerebral hypoperfusion that most often results from hypotension.Many forms of syncope are...
, surrender, or flee when shot or shot at. Emotional fainting is the likely reason for most "one-shot stops", and not an intrinsic effectiveness quality of any firearm or bullet; there are many documented instances where people have instantly dropped unconscious when the bullet only hit an extremity, or even completely missed. Additionally, the muzzle blast and flash from many firearms are substantial and can cause disorientation, dazzling, and stunning effects. Flashbangs (stun grenades) and other less-lethal "distraction devices" rely exclusively on these effects.
Pain
Pain
Pain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...
is another psychological factor, and can be enough to dissuade a person from continuing their actions.
Temporary cavitation can emphasize the impact of a bullet, since the resulting tissue compression is identical to simple blunt force trauma. It is easier for someone to feel when they have been shot if there is considerable temporary cavitation, and this can contribute to either psychological factor of incapacitation.
However, if a person is sufficiently enraged
Rage (emotion)
Rage is a feeling of intense anger. It is associated with the Fight-or-flight response and oftentimes activated in response to an external cue, such as the murder of a loved one. The phrase, 'thrown into a fit of rage,' expresses the immediate nature of rage that occurs before deliberation. If left...
, determined, or intoxicated they can simply shrug off the psychological effects of being shot. Therefore, such effects are not as reliable as physiological effects at stopping people. Animals will not faint or surrender if injured, though they may become frightened by the loud noise and pain of being shot, so psychological mechanisms are generally less effective against non-humans.
Penetration
According to Dr. Martin FacklerMartin Fackler
Dr. Martin L. Fackler is a retired Colonel in the US Army's Medical Corps, he was a battlefield surgeon, and the head of the Wound Ballistics Laboratory for the US Army’s Medical Training Center, Letterman Institute....
and the International Wound Ballistics Association (IWBA), between 12.5 and 14 inches (318 and 356 mm) of penetration in calibrated tissue simulant is optimal performance for a bullet which is meant to be used defensively, against a human adversary. They also believe that penetration is one of the most important factors when choosing a bullet (and that the number one factor is shot placement). If the bullet penetrates less than their guidelines, it is inadequate, and if it penetrates more, it is still satisfactory though not optimal. The FBI's penetration requirement is very similar at 12 to 18 inches (305 to 457 mm).
A penetration depth of 12.5 to 14 inches (318 and 356 mm) may seem excessive, but a bullet sheds velocity—and crushes a narrower hole—as it penetrates deeper, while losing velocity, so the bullet might be crushing a very small amount of tissue (simulating an "ice pick" injury) during its last two or three inches of travel, giving only between 9.5 and 12 inches of effective wide-area penetration. Also, skin is elastic and tough enough to cause a bullet to be retained in the body, even if the bullet had a relatively high velocity when it hit the skin. About 250 ft/s (76 m/s) velocity is required for an expanded hollow point bullet to puncture skin 50% of the time.
The IWBA's and FBI's penetration guidelines are to ensure that the bullet can reach a vital structure from most angles, while retaining enough velocity to generate a large diameter hole through tissue. An extreme example where penetration would be important is if the bullet first had to enter and then exit an outstretched arm before impacting the torso. A bullet with low penetration might embed itself in the arm whereas a higher penetrating bullet would penetrate the arm then enter the thorax where it would have a chance of hitting a vital organ.
Overpenetration
Overpenetration is when a bullet goes through its target and out of the other side, potentially going on to damage something or someone else.Other hypotheses
These hypotheses are a matter of some debate among scientists in the field:Energy transfer
The energy transfer hypothesis states that the more energyEnergy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
that is transferred to the target, the greater the destructive potential.
Energy is a function of mass and the square of velocity. Generally speaking, it is the intention of the shooter to deliver an adequate amount of energy to the target via the projectile/s. Projectiles such as rifle bullets, high velocity handgun bullets and shotgun slugs can over-penetrate. Projectiles such as handgun bullets and shot can under-penetrate. Projectiles that reach the target with too low a velocity or bird shot may not penetrate at all. All the above conditions affect energy transfer.
Over-penetration is detrimental to stopping power in regards to energy. This is because a bullet that passes through the target does not transfer all of its energy to the target. Despite decreased tissue damage due to loss of transferred energy on an over-penetrating shot, the resulting exit wound would cause increased blood loss and therefore a decrease in blood pressure in the victim. This effect on both persons and game animals is likely to be incapacitating over the length of the entire shooting event.
Under-penetration is also detrimental to stopping power. Projectile/s that do not transfer enough energy to the target may fail to create a fatal wound cavity. Also vital organs may not be reached, thereby limiting the amount of tissue damage, blood loss, and/or loss of blood pressure.
Non-penetration of projectile/s may only deliver enough energy to create bruising, punctures and or blunt force trauma. All of which may result in internal injury solely through the force of the impact but not stop the target. A notable example of projectiles designed to deliver stopping power without target penetration are Flexible baton round
Flexible baton round
A bean bag round, also known by its trademarked name flexible baton round, is a baton round fired as a shotgun shell used for less lethal apprehension of suspects.-Description:...
s (commonly known as "beanbag bullets"), a type of reduced-lethality ammunition.
As mentioned above, there are many factors that affect "stopping power." Within this theory energy transfer is related to destructive potential; however, the importance of energy transfer in determining the stopping power of projectiles (when compared to other factors like location of the wound and wound cavity size) is a controversial topic.
The force exerted by a projectile upon tissue is equal to the bullet's local rate of kinetic energy loss, with distance
(the first derivative of the bullets kinetic energy with respect to position). The ballistic pressure wave is proportional to this retarding force (Courtney and Courtney), and this retarding force is also the origin of both temporary cavitation and prompt damage (CE Peters).Hydrostatic shock
Hydrostatic shockHydrostatic shock
Hydrostatic shock or hydraulic shock describes the observation that a penetrating projectile can produce remote wounding and incapacitating effects in living targets through a hydraulic effect in their liquid-filled tissues, in addition to local effects in tissue caused by direct impact...
is a theory of terminal ballistics
Terminal ballistics
Terminal ballistics, a sub-field of ballistics, is the study of the behavior of a projectile when it hits its target. It is often referred to as stopping power when dealing with human or other living targets. Terminal ballistics is relevant both for small caliber projectiles as well as for large...
that wounding effects are created by a shock wave in the tissues of the target. It is argued that evidence of such shock can be seen in ultra-high-speed images of supersonic bullets passing through various objects such as fruit; the fruit explodes due to the shock waves caused by the bullet passing through at high speed. Proponents of the theory contend that damage to the brain from hydrostatic shock from a shot to the chest occurs in humans with most rifle cartridges and some higher-velocity handgun cartridges.
Knockback
The idea of "knockback" is a subset or simplification of energy transfer theory, and states that a bullet of sufficient caliber at sufficient speed which transfers all its energy to a subject has enough force, by sheer momentum of the bullet, to stop forward momentum of an attacker and knock them backwards or downwards. The idea was first widely expounded in ballistics discussions during American involvement in Philippine insurrections and, simultaneously, in British involvement in the Caribbean, when front-line reports stated that the .38.38 Long Colt
The .38 Long Colt is a cartridge introduced by Colt's Manufacturing Company in 1875, and was adopted as a standard military pistol cartridge by the United States Army in 1892 for the Colt New Army M1892 Revolver. It is slightly more powerful than the .38 Short Colt, or .38 SC. The .38 Long Colt...
caliber revolvers carried by U.S. and British soldiers were incapable of bringing down a charging warrior. Thus, in the early 1900s, the U.S. reverted to the .45 Colt in single action revolvers, and later adopted the .45 ACP
.45 ACP
The .45 ACP , also known as the .45 Auto by C.I.P., is a cartridge designed by John Browning in 1904, for use in his prototype Colt semi-automatic .45 pistol and eventually the M1911 pistol adopted by the United States Army in 1911.-Design and history:The U.S...
cartridge in what was to become the M1911A1 pistol and the British adopted the .455 Webley
.455 Webley
.455 Webley is a British handgun cartridge, most commonly used in the Webley top break revolvers Marks I through VI.The .455 cartridge was a service revolver cartridge, featuring a rimmed cartridge firing a .45 bullet at the relatively low velocity of 650 ft/s...
caliber cartridge in the Webley Revolver
Webley Revolver
The Webley Revolver was, in various marks, the standard issue service pistol for the armed forces of the United Kingdom, the British Empire, and the Commonwealths from 1887 until 1963.The Webley is a top-break revolver with automatic extraction...
. The larger cartridges were chosen largely due to the Big Hole Theory (a larger hole does more damage), but the common interpretation was that these were changes from a light, deeply penetrating bullet to a larger, heavier "manstopper" bullet.
Though popularized in television and movies, and commonly referred to as "true stopping power" by novice or uneducated proponents of large powerful calibers such as .44 Magnum
.44 Magnum
The .44 Remington Magnum, or simply .44 Magnum, is a large-bore cartridge originally designed for revolvers. After introduction, it was quickly adopted for carbines and rifles...
, the effect of knockback from a handgun and indeed most personal weapons is largely a myth. The momentum
Momentum
In classical mechanics, linear momentum or translational momentum is the product of the mass and velocity of an object...
of the so-called "manstopper" .45 ACP
.45 ACP
The .45 ACP , also known as the .45 Auto by C.I.P., is a cartridge designed by John Browning in 1904, for use in his prototype Colt semi-automatic .45 pistol and eventually the M1911 pistol adopted by the United States Army in 1911.-Design and history:The U.S...
bullet is approximately that of a 1 pound (0.45359237 kg) mass dropped from a height of 11.4 feet (3.5 m).It should be noted that momentum is very different from kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...
; an equivalent kinetic energy [855 ft·lbf (1159 J)] of a typical .45 ACP bullet is that of a 60 pound (27 kilogram) mass dropped from a height of 14 feet (4.3 meters). Such a force is simply incapable of arresting a running target's forward momentum. In addition, bullets are designed to penetrate instead of strike a blunt force blow, because, in penetrating, more severe tissue damage is done. A bullet with sufficient energy to knock down an assailant, such as a high-speed rifle bullet, would be more likely to instead pass straight through, while not transferring the full energy (in fact only a very small percentage of the full energy) of the bullet to the victim.
The "knockback" effect is however commonly "seen" in real-life shootings, and can be explained by physiological and psychological means. Humans encountering a physical hit, be it a punch or a bullet, are conditioned to absorb the blow by moving in the same direction as the force. The physical effect against a non-penetrating weapon is to reduce the force felt by the blow, and in addition, retreating from an attack increases the distance such an attack must cover, which in the case of non-projectile weapons such as fists or a knife, places the target out of range of further attack. In addition, there is a theoretical sociological explanation, that in modern civilization, with far greater separation by most individuals from violence, hunting, and combat, normal individuals may simply recoil, buckle, or fall backward when hit by a bullet, even when in pure physiological terms they are perfectly capable of continuing to charge.
Although knockback is not possible with a handgun bullet, it can be an actual effect occurring in reaction to being hit by a massive slug, such as a rubber bullet or sandbag fired from a shotgun
Shotgun
A shotgun is a firearm that is usually designed to be fired from the shoulder, which uses the energy of a fixed shell to fire a number of small spherical pellets called shot, or a solid projectile called a slug...
. The dynamics of a slug round are quite different than penetrating bullets; the projectile is here designed not to penetrate but instead to strike a hard, blunt force blow, and as the momentum carried by a shotgun cartridge is greater than practically any production handgun cartridge, the force imparted is comparable to a hard punch and is capable, by physics, of affecting a person's forward motion. In any case, due to conservation of momentum, the gun's recoil is always larger than the bullet's knockback, as some momentum of the bullet is lost during flight, and if the bullet penetrates through the target it will not have imparted all its momentum into the target.
One-shot stop
This hypothesis, promoted by Evan P. Marshall, is based on statistical analysis of actual shooting incidents from various reporting sources (typically police agencies). It is intended to be used as a unit of measurement and not as a tactical philosophy, as mistakenly believed by some. It considers the history of shooting incidents for a given factory ammunition load, and compiles the percentage of "one-shot-stops" achieved with each specific ammunition load. That percentage is then intended to be used with other information to help predict the effectiveness of that load getting a "one-shot-stop." For example, if an ammunition load is used in 10 torso shootings, incapacitating all but two with one shot, the "one-shot-stop" percentage for the total sample would be 80%.Some argue that this hypothesis ignores any inherent selection bias
Selection bias
Selection bias is a statistical bias in which there is an error in choosing the individuals or groups to take part in a scientific study. It is sometimes referred to as the selection effect. The term "selection bias" most often refers to the distortion of a statistical analysis, resulting from the...
. For example, high-velocity 9 mm hollow point
Hollow point bullet
A hollow point is an expanding bullet that has a pit or hollowed out shape in its tip, generally intended to cause the bullet to thin upon entering a target in order to decrease penetration and disrupt more tissue as it travels through the target. It is also used for controlled penetration, where...
rounds appear to have the highest percentage of one-shot stops. Rather than identifying this as an inherent property of the firearm/bullet combination, the situations where these have occurred need to be considered. The 9 mm has been the predominantly used caliber of many police departments, so many of these one-shot-stops were probably made by well-trained police officers, where accurate placement would be a contributory factor. However, Marshall's database of "one-shot-stops" does include shootings from law enforcement agencies, private citizens, and criminals alike.
Critics of this theory point out that bullet placement is a very significant factor, but is only generally used in such one-shot-stop calculations, covering shots to the torso.
Since 2006, after the conviction of retired school teacher Harold Fish in Arizona for second degree murder during a self-defense shooting, some CCW
Carrying concealed weapon
Concealed carry, or CCW , refers to the practice of carrying a handgun or other weapon in public in a concealed manner, either on one's person or in proximity....
holders in the United States have elected to switch from carrying hollow-point bullets, and especially 10mm Auto caliber weapons with perceived higher one-shot stopping power, to carrying smaller caliber weapons. Fish's conviction for killing a homeless man with a history of dangerous violent behavior and mental instability who attacked Fish while hiking on a remote trail, was obtained through a jury trial by stressing that Fish overreacted, through choosing to use the increased stopping power of 10 mm hollow point
Hollow point bullet
A hollow point is an expanding bullet that has a pit or hollowed out shape in its tip, generally intended to cause the bullet to thin upon entering a target in order to decrease penetration and disrupt more tissue as it travels through the target. It is also used for controlled penetration, where...
bullets. State law in Arizona has subsequently been changed, such that the state now has the burden to prove that a self defense shooting was not in self defense, whereas the burden previously, before the Fish incident, was that the shooter on trial had to prove that the shooting was in fact, done in self defense. The conviction has since been thrown out by the Arizona Court of Appeals. CCW training classes often advise the use of bullets that are identical to those used by local police, in type (FMJ or hollow point) and caliber, to prevent an overreaction prosecution.
Big Hole School
This school of thought says that the bigger the hole in the target the higher the rate of bleed-out and thus the higher the rate of the aforementioned "one shot stop". According to this theory, as the bullet does not pass entirely through the body, it incorporates the energy transfer and the overpenetration ideals. Those that support this theory cite the .40 S&W.40 S&W
The .40 S&W is a rimless pistol cartridge developed jointly by major American firearms manufacturers Winchester and Smith & Wesson. The .40 S&W was developed from the ground up as a law enforcement cartridge designed to duplicate performance of the FBI's reduced velocity 10mm cartridge which could...
round, arguing that it has a better ballistic profile than the .45, and more stopping power than a 9×19mm Parabellum.
The theory centers on the "permanent cavitation" element of a handgun wound. A big hole damages more tissue. It is therefore valid to a point, but penetration is also important, as a large bullet that does not penetrate will be less likely to strike vital blood vessels and blood-carrying organs such as the heart and liver, while a smaller bullet that penetrates deep enough to strike these organs or vessels will cause faster bleed-out through a smaller hole. The ideal may therefore be a combination; a large bullet that penetrates deeply, which can be achieved with a larger, slower non-expanding bullet, or a smaller, faster expanding bullet such as a hollow point.
In the extreme a heavier bullet (which preserves momentum greater than a lighter bullet of the same caliber) may "overpenetrate", passing completely through the target without expending all of its kinetic energy. So-called "overpenetration" is not an important consideration when it comes to wounding incapacitation or "stopping power", because: (a) while a lower proportion of the bullet's energy is transferred to the target a higher absolute amount of energy is shed than in partial penetration, and (b) overpenetration creates an exit wound.
Other contributing factors
As mentioned earlier, there are many factors, such as drug and/or alcohol levels within the body, body mass indexBody mass index
The body mass index , or Quetelet index, is a heuristic proxy for human body fat based on an individual's weight and height. BMI does not actually measure the percentage of body fat. It was invented between 1830 and 1850 by the Belgian polymath Adolphe Quetelet during the course of developing...
, mental illness
Mental illness
A mental disorder or mental illness is a psychological or behavioral pattern generally associated with subjective distress or disability that occurs in an individual, and which is not a part of normal development or culture. Such a disorder may consist of a combination of affective, behavioural,...
, motivation levels, body part strike (e.g. "armpit hold") which may determine which round will kill or at least catastrophically affect a target during any given situation.
External links
- What You Need to Know About Stopping Power
- Wound Ballistics
- Reality of the Street? A Practical Analysis of Offender Gunshot Wound Reaction for Law Enforcement
- Handgun Wounding Factors and Effectiveness
- Ballistic gelatin testing done by "GoldenLoki"
- What We Didn't Know Hurt Us (PDF)
- One Shot Drops - Surviving the Myth
- Ammunition for the Self-Defense Handgun - anonymous
- Terminal effects of the Mk 7 .303 British cartridge
- Discrepancies in the Marshall & Sanow "Data Base": An Evaluation Over Time
- The Truth About Ammunition