• Ken Kraushaar

the .223 on 60 minutes


Good morning all, I hope this week finds you well as we get closer and closer to Christmas and the end of the year.

Once again there’s been a media story covering the AR-15 (60 minutes) showing what the .223 Remington ammunition does do a ballistic gel block in comparison to a 9mm shot into the same block, and accompanying it are letters to the editor by people who see this seemingly devastating wound caused to the block, and exclaim that surely hunters don’t need to use this round, because what they saw in the gel was an explosion!

The purpose of this blog is to address exactly what is seen, and why it’s neither a fair comparison, nor is it actually accurate as far as singling out the .223 Remington round as somehow more dangerous than other rounds.

I do want to warn the reader that some of the images used as examples may be disturbing but they are necessary to illustrate the points I'm trying to make. some of this will be a direct rehashing of information which I've previously posted about, but it's important to cover it again in the context of responding to the program.

A history lesson: For starters, a little history lesson: the .223 Remington round has been available to hunters since the late 1950s for use in their semi-automatic rifles, and then was later adopted by the us military for use in their original armalite-15 / M-16 rifle platform. The reason for this was due to the changing battlefield landscape at the time, and to reduce both rifle weight and allow soldiers to carry more ammunition into battle- no longer was the American warfighter fighting on the kind of terrain we encountered in WWII, but rather, the terrain encountered in Korea and Vietnam. The M-16 was chambered in the 5.56mm NATO round, which can handle higher pressures than the standard .223 chambered rifle.

Previous battlefield rifles, such as the M1 Garand, as well as the M-14 used larger caliber ammunition, such as the 30-06 Springfield rifle round, and the .308 Winchester/7.62x51 NATO round, respectively, and each were equipped with heavy wooden stocks and steel receivers. These guns were hard to lug around, and were limited by weight as to what the soldier could carry into battle, they were also more prone to rusting due to the humidity of the Asian continent. The AR-10, which was the precursor to the M-16, and was also developed by Armalite/Eugene Stoner (hence the AR in AR-15) solved part of that problem, in that it was made from aluminum alloy and steel, which reduced the weight of the weapon, but it did not satisfy all of the needs the military had put forth, it was still limited in the amount of ammunition that could be carried.

The adoption 223 Remington rifle round, it’s redesign into the 5.56 nato round to accommodate higher pressures, and redesign of the rifle into what would become the M-16 changed this, in that you could carry more ammunition at a reduced weight, however, it sacrificed the punch of the previous rounds used by the military, in favor of the ability to carry more ammunition as well. The new round, was lighter, and the new firearm, which was made out of aluminum alloy and plastic, was much lighter, enabling the US warfighter to carry more ammunition and reduce their overall weight. It also had the benefit of being less susceptible to rust due to the humidity of Southeast Asia.

There were also issues that the military had to overcome in use of the round itself. Early rifles were noted to have issue with bullet flight stability while using the new round, causing excessive yaw while in flight before it hit its target, which affected accuracy. This was addressed by adopting a faster barrel twist rate than what was originally used in the M-14 (1:8” twist, vs. the former 1:14” twist).

The military at the time also adopted a philosophy of “shoot one, kill two” with the premise being that you would shoot 1 enemy combatant, and kill both him and his friend when the friend came to rescue his wounded comrade. This was due to the fact that the .223 Remington/5.56 NATO round lacked the same terminal ballistics/wound ballistics as the 30 caliber rifle rounds that it replaced. The drawbacks that were also encountered by US troops in the Vietnam war theater were a reduced range of fire as well, which is also encountered by our troops today.

The engagement of enemy combatants with this rifle, at maximum has an effective range of 400 yards, whereas enemy combatants using AK-47 and SKS rifles could engage from further away. This gap was closed by still employing 30 and 50 caliber machine guns, but these were not always available to ground troops who were engaged in jungle warfare.

Currently, our troops are asking for an updated platform with better ballistics precisely because this round is not exactly ideal for warfighting, due to its limited effective range (400 yards) and terminal ballistics.

The science behind what is happening in the video: So there are a couple of things which are going on in the video which are either wrong, or disingenuous at best. What do I mean by that? The person showing the difference between the effects of a 223 versus a 9mm in a block of ballistics gel is being disingenuous with the viewer because she is trying to compare two different bullets traveling at two different velocities, with different ballistics, weights, diameters, and platforms of use. They are not analogous.

The target audience, as with most things covered by the media, are not for people who know what they are looking at; it is for people who have no idea what they are looking at, and will exclaim in horror at the appearance of a more devastating effect of a rifle round hitting a target, versus a pistol round, and it is usually these people who will vote for legislation against firearms. Once again, below is the 9mm vs. 223 shown in the 60 minutes television spot.

Looks devastating, doesn’t it? But optics, seldom tell the whole story, and in this case, you’re comparing two different sets of ballistics in this case.

The reality is that the faster a bullet travels, regardless of caliber, the more effect it will have on the target, so, the 223 Remington round will have a larger temporary cavity due to speed alone, versus the 9mm bullet, even though the 9mm bullet is larger in diameter; further- any rifle round or bullet fired from a longer barrel will have a greater velocity impact, so even the 9mm round shot from a carbine barrel, would affect the gel differently.

If we’re going based off of the temporary cavity, and making the determination based off of what looks devastating, then the picture below of a fast moving 357 magnum pistol round should also be considered.

Or, how about a 338 lapua round traveling at 3000ft/s

See the difference? Why would anyone need any of these rounds? And why were they not featured as well? Because it doesn’t make for good tv, the weapons in which these rounds are used are not often used in mass murders. it's important to note the temporary cavity (the big explosion) doesn’t paint the whole picture in any of these cases.

That said, velocity does count for something. Even shooting the same diameter bullet out of different guns will change the way a bullet behaves. So lets focus on the bullet comparisons used.

The 223 rifle round travels at 3240ft/s (depending on the bullet and powder charge used) while the 9mm travels at roughly half that speed at 1,120ft/s. Bullet geometry, mass, and material strength all matter as well as far as the extent of damage is concerned (terminal/wound ballistics, i.e. what it does upon impact). The 357 magnum shown above, for instance, only travels at 1450 ft/s , but it’s temporary wound cavity is huge. Again, it’s velocity is roughly half that of the 223, and half that of the lapua, , and only roughly 200 ft/s faster than the 9mm, while the lapua travels at about 3000ft/s, just 240 ft/s slower than the 223. So it's safe to assume that bullet mass also affects the target.

Another example that centered around the 9mm nato round: an experiment was performed for the US Air force academy’s form OMB No. 0704-0188 in 2011 by Amy Courtney and Michael Courtney using 9mm bullets. The bullets they used were:

  • 9 mm NATO 124 grain Full Metal Jacket (FMJ) non-expanding

  • 9 mm NATO 127 grain Winchester Ranger rapid-expanding

  • 9 mm NATO 147 grain Winchester Ranger SXT rapid-expanding

  • 9 mm NATO 147 grain Winchester Jacketed Hollow Point* slow-expanding

In the first example, the 124 grain full metal jacket (FMJ) projectile exerts relatively low forces on the tissue because it has a lower rate of energy loss in the tissue. It does not have an expanding tip, nor is it designed to fragment. The oscillations in force and wound profile are due to tumbling of the bullet as it penetrates – where the bullet has a larger effective cross-sectional area at a given velocity, the forces are higher and the wound profile larger.

In the second example The 127 grain Winchester Ranger SXT is also a 9mm NATO round; however, it has a higher impact energy and the tip expands quickly, so that energy is lost quickly as the bullet penetrates. This results in very high forces on the tissue at shallow penetration depths. The result is a much larger wound profile than for the FMJ round (a mathematical explanation of why this is the case is presented by Peters in “A mathematical-physical model of wound ballistics”.

In the third example, the 147 grain Winchester Ranger SXT has similar physical characteristics but lower impact energy compared to the 127 grain Ranger; so while the shapes of the force penetration curve and wound profile are similar, they are smaller for the 147 grain Ranger.

In the fourth example, the 147 grain Winchester Jacketed Hollow Point (known as Winchester White Box, or WWB) has the same mass as the 147 grain Ranger but a smaller retarding force due to the slow expansion of the tip. The peak retarding force and the peak diameter of the temporary cavity for this bullet is similar to that for the 124 grain FMJ.

The results of this experiment showed that bullets of the same caliber can have very different wounding potentials based on penetration into 10% ballistic gelatin.

Sometimes bullets pass through intermediate barriers such as heavy clothing, wood, metal, wallboard or auto glass before penetrating tissue. In such situations, the bullet tip can be altered, changing its penetration and energy loss characteristics in tissue. Sometimes these changes may be unexpected.

Projectile or bullet injuries may be classified as “low energy” or “high-energy,” which describe the amount of damage to the tissues. The factor that most affects the injury severity is the amount and the efficiency of energy transfer, which is mostly related to kinetic energy that is presented by the equation “Energy transferred = ½ M [(V entering)2 − (V exiting)2 ] (M – mass; V – velocity)” in a bullet that does not “waste” energy on deforming.

Other suggested theories are the momentum theory expressed as “Mass × Velocity” and the power theory related to “Mass × Velocity3 ”. Ballistic wounds can be classified, according to the amount of energy causing them, into: high energy (>1,000 J); medium energy (250–1,000 J); low energy (>250J). The amount of kinetic energy delivered by the hitting body (projectile, bullet, shrapnel…) at the time of impact depends mainly upon the squared velocity (E = ½MV2 ) and in a lesser degree to the projectile body mass. The longer the range, the lower the velocity is at impact. The velocity is traditionally classified to high or low velocity, commonly refers to slower than the speed of sound in air, approximately 1,100 fps [usually projectile speed is below 1,000 to 2,000 feet per second (fps)], which generally is more common in the civilian population and usually causes less severe injuries as opposed to higher velocity (projectile speed is greater than 2,000 to 3,000 fps) such as military and hunting weapons which cause more severe damage and at high speed (4,760 fps), the rate of energy conversion into mechanical tissue destruction can become proportional to the third power of velocity or even higher. The velocity of the M-16 bullet is three times that of the 0.22 bullet.

This explains, why although AR-15 has almost the same caliber and mass as the 0.22 its kinetic energy is almost 10 times than the 0.22. The longer the barrel, the more time available for bullet acceleration by the expanding gases (therefore, for identical rounds, the gun with a shorter barrel produces a lower-velocity bullet)

Note the picture above, the x ray photograph shows the difference between a 9mm, hollow point, (a,b) and a full metal jacketed bullet of the same caliber (c,d). note how the hollow point is much more “severe” than the full metal jacket. see the difference in damage caused by the same caliber bullet?

Now, take this example shooting into 60 lbs of cow meat below. Again, I want to reiterate that this is not analogous to human testing, but rather to illustrate what two different type kinds of bullet shot out of the same gun, and same caliber, can do. Cow meat, and the human body, are vastly different from one another, and will obviously react differently when shot. (more on that later).

In the first example, (a,b) the shooter used a Hornady 223 40 gr Varmint Express round. In the second, he used a PMC 223 55 gr FMJ. Note the difference. See the difference in size of the entry and exit wounds, and the amount of tissue displacement? Why is this? Well, the hornady bullet, even though it is smaller in weight, is a hollow point bullet with a “ballistic tip” (i.e. a plastic tip that aids it in flight until it impacts a target,) and travels at 3800 feet per second and is made to break up, while the PMC 223 has a full metal jacketed bullet, travels at 3200 feet per second. Because the bullet which the PMC uses is not meant to break up, we end up with what's referred to as a "pencil hole" wound, which is just a straight pass through.

Now, take a look at what another commonly found .308 winchester bullet (berger hunting vld) impact has upon a deer. Bigger bullet, slower velocities, but massive wounding on a deer at the exit wound caused by a bullet that is made to come apart (a boat-tail hollow point).

Please note, for informational purposes, I will cover bullet types further below. In light of these examples, it is extremely important to recognize that the reality is that a bullet can do just about anything when it interacts with a body, human or otherwise, depending on distance, barrel length, caliber, bullet type, and velocity used. It is no more accurate to compare a .22 long rifle to a .223 Remington, than it is to compare a 9mm parabellum to a .223 Remington, as there are even differences in what bullets that have the same diameter and same cartridge type, are capable of doing. It is also important to recognize that most calls for bans on weapons, investigative reporting, etc, only focus on commonly used calibers in “mass-shootings”, hence why a 308, which is even more devastating than a .223, isn’t focused upon, mainly because it isn’t used in mass shootings, drive-bys, etc. so again, the 60 minutes piece isn’t being completely honest with the viewer, because it is focusing on the prevailing media theme, versus showing an accurate depiction as the comparisons being shown are not equal with regard to ballistics. The ballistics field: two camps and how they view wounding Now experts in the field can be categorized into two camps: the medical group, and the engineering group. The medical group sees the wounds (even the wounds that were caused by an identical bullet, at an identical entrance angle, into an identical location) as individually different and each must be treated through a medical procedure based on the caregivers’ experience, observations and understanding. The engineering camp believes that wounding can be quantified by physics. They believe that relationships (potentially very complex) can be drawn based off of energy, momentum, material properties, etc. which can be used to quantify the effects of projectiles against persons.

What actually is going on is probably somewhere in between the ideas of both groups, but to date, no-one has found the right combination that would bring it all together. So, based off of this we can conclude that any “expert” being interviewed that is basing their opinion on only one facet of information which makes a blanket statement about the effects of a particular rifle round, in this case, the .223 , isn’t doing so based off of 100% science, but rather based on their opinion/observation about a particular round that is encountered more often (in terms of rifle shots), and they simply don’t have the same frame of reference that would include other rifle wounds and thus, would not allow them to be completely objective in their assessments; further, in this case, being objective isn’t the point- entertainment, ratings and influencing public opinion, however, are, , and they are making a skewed comparison in order to do so.

Conversely, comparing the .223 to a .22lr, is also making a skewed comparison, as the two rounds, aside from bullet diameter, have vastly different ballistics.

Based off of the previous information, it would be very difficult to absolutely define incapacitation and to cover all possible aspects of wounding with what we saw in the 60 minutes spot (keeping in mind this was only a 15 minute segment). Incapacitation:

When defining incapacitation, we must set certain criteria. The criteria used by Donald Carlucci and Sydney Jacobsen in the college textbook “Ballistics: Theory and Design of Guns and ammunition” are:

  • Whether the targets survive the wounding

  • What targets are able to do after they’re hit

  • How long the targets are able to do it after they’re hit.

As such, there are several misconceptions about wounding that would need to be addressed in order to meet these criteria.One misconception is that the temporary cavity is the major cause of tissue damage. This has probably grown out of extremely interesting videos that have been posted on youtube, the internet, or shown on tv (including the 60 minute spot,) that show massive temporary wound cavities caused by the projectile being fired into a block of ballistics gel. It is difficult to imagine as a viewer that these cavities would not cause huge amounts of damage and kill you. In fact this topic is rather hotly debated by expert in the field. It is suggested, however, that only 20% of all tissue damage is caused by the temporary cavity. Ballistic gelatin, for that matter is an isotropic (uniform in all directions) medium intended to simulate soft tissue, though it is not an exact match, and most closely mimics muscle tissue.

Therefore the wound profiles shown, though actual, are somewhat idealized compared to what would happen if the path of the projectile were near to or strikes a bone. Bone impact results in a rapid loss of energy, high forces, and possible fragmenting of the projectile as well as of the bone itself.

Another misconception, pointed out by Peters, is that tissue damage is proportional to the kinetic energy of the projectile. It is suggested that there is a relationship, but it is non-linear. It was thought, and likely still is, that the sizes of the maximum temporary cavity and permanent cavity were somehow proportional to the energy deposited into the target by the projectile. It is suggested that there is a non-linear relationship, but additionally, over some ranges of data, it can be linearized, which is possibly why the conclusion was drawn in the first place.Engineers who look at a person as an engineering structure, for instance, at some point assume that the volume of the permanent of cavity must, in some way, result from material ejected from the wound. That is: that the permanent cavity volume must equal the volume of the material ejected.This is not the case since a permanent cavity remains even when the bullet stops in the target.The cause of the permanent cavity is primarily due to inelastic deformation of the tissue.Siting Peters and other researchers, Carlucci/Jacobsen state that temporary cavities in humans or animals will be different sizes than those developed in gelatin blocks.

Currently this is a very active area of research, so siting that they are 100% analogous isn’t being 100% honest with the viewer. There are even differences in cavity formation in animals and humans, to the extent that there is no scaling law that has been universally established, thus making comparisons made by doctors attesting to a round’s effects to human wounding as an analog, disingenuous as well, as they are non-analogous.

One of the more interesting aspects of wound ballistics, is the internal effect on a human body. This is compounded by Hollywood’s depiction of what happens when you are shot. In Hollywood action films throughout the 80’s, 90’s, and 2000’s, we routinely see bad guys picked up and thrown several feet backwards by the impacts of small arms projectiles. When the numbers are worked out on a 7.62mm (.308 cal.) projectile at point blank range, for instance, the energy exchange (assuming the bullet remains in the target) is such that the rearward velocity is less than 0.2mph. in fact, most human targets usually just fall towards the shooter (unless they were running away when hit.) this is one reason we do not use Hollywood or tv to define what a gun or projectile will do: these big hits, automatic fire, etc. are all done for dramatic effect. They are not analogous to what really happens in real life, nor should Hollywood cinematic efforts be used as a example when defining legislation.

Bullet types: Next, I’ll talk a little more about bullet types: 1) solid slug, 2) full metal jacket 3) semi-jacketed, 4) hollow point, and 5) steel core. A solid slug is nothing more than a soft metal projectile (usually lead or similar soft metal) that is engraved along its body length by rifling to impart spin. A full metal jacketed (fmj) projectile is a solid slug that is coated with a material such as copper, to better withstand the firing stresses and whose residue can easily be removed from the bore of a gun barrel. A semi jacketed bullet, or open tipped bullet, is jacketed up to a small region of the nose. This region, being softer than the jacketed region and unable to withstand the radial stresses upon impact, expands as it enters the target, theoretically causing a more extensive wound. A hollow point projectile is similar except that the tip is actually concave. It uses fluid mechanics, couple with the lower radial strength upon penetration to open larger. Finally, the steel core projectile has a hard core for penetration of metallic structures or textile armor.

One common type, that is not listed, is the wad cutter type, which can be fully jacketed, or not but have a cup like shape to the nose so that they punch a nice clean hole through paper targets.

Wounding types: Earlier I mentioned terms such as temporary cavity and permanent cavity. I’ll define some of these terms, so that you can better understand what we’re talking about. A laceration is a cut through tissue. A projectile’s primary means of incapacitation is through laceration. Because of the complicated nature of the human body, a projectile that penetrates can do anything from causing minor bleeding, if no major artery or organ is damaged, to rapid death if a vital organ is hit. If a projectile hits bone tissue or even meets a severe gradient in density, it can be deflected considerably.

When a projectile enters a human body, it sends stress waves through the body. These waves and associated rarefactions can even cause damage, but it is generally agreed upon that these waves will primarily damage nerves and can possibly collapse organs.

The temporary cavity is created through the process of cavitation caused by the fluid mechanics of the body and it’s interaction with the bullet. It results from the adherence of the fluid molecules to the surface of the projectile, and when the shear stress drops to zero on the surface, the flow separates. This separation bubble can grow to 40 times the projectile diameter as the projectile passes through the body. Once the projectile has passed by, however, the radial energy that it imparted to the tissue is removed, and the elasticity of the tissue causes it to immediately collapse to a much smaller size, the largest extent that this bubble reaches is known as the maximum temporary cavity, while the small, equilibrium cavity is known as the permanent cavity. I mention these two terms because it is important to note why, the large explosion that was seen in the gel demonstration on 60 minutes, really wasn’t a big huge devastating injury, but rather, was the generation of the temporary cavity, which is caused by, and affected by the speed of the bullet. Now something that has a dramatic effect on the cavitation is projectile yaw. Projectile yaw is the tumbling of the bullet when it impacts the human body. The projectile is usually unstable in the human body. This cases it to tumble considerably and possible tumble. As one can imagine, because of the relatively immense presented area of a projectile flying with a large yaw, the separation and associated cavitation can be huge. In fact, if a projectile rotates 180 degrees, it will exit base first, which will affect the size of the exit wound considerably.Analysis of this flight behavior is extremely difficult because projectiles perform differently depending on what tissue they happen to be passing through.The following is a short list of types of tissues that affect bullet passage through a living creature:

  • Bone

  • Skull/brain

  • Thorax/ribs

  • Lung

  • Intestine/stomach/bladder

  • Muscle

Each of these tissues will have a different effect on the projectile. It is even important if an organ is flaccid (empty) or not, or whether the target is living, or dead (again, making dead animal testing non-analogous to effects on a human.) For simplicity’s sake, the most general research is carried out on muscle tissue, and that is where a great deal of work has been expended to come up with a suitable surrogate testing material (gel testing.)

Assuming we are discussing muscle tissue penetration, the first thing that we must recognize is that tissue has a non-negligible tearing stress that must be overcome. This additional stress must be incorporated into a drag model when trying to determine the effects a bullet has on a material. I cannot emphasize enough the complexity of the problem. Even though, we shall assume penetration into homogenous muscle tissue, we must always keep in mind a penetration event is much more complicated, when making blanket statements regarding effects of projectiles, especially when making statements to media outlets who are looking to inform or influence their viewers.

We know that as a projectile enters muscle tissue, what was once a relatively simple matter of aeroballistics becomes a more complicated problem of continuum mechanics: in air, there was no yield stress to overcome (this is the major difference); the viscosity and density of muscle are different than air.

If the impact angle is low enough, the nose of the projectile will enter first. The usual decrease in shear stress as we progress along the projectile will occur and at some point the shear stress will reach zero and the tissue will separate from the projectile forming the cavitation bubble. Throughout this event, the projectile will slow down due to drag. There will also be a larger overturning moment than in air because of the large force on the small area of the nose (higher density in dynamic pressure) and in addition the separation will take place ahead of the center of gravity, increasing the moment arm. The drag force will also include the force required to overcome the cohesive stresses in the tissue (or tearing stress) , which is not usually included in the aerodynamic model.

What once was a transonic/supersonic flow field becomes a transonic (at best) or a subsonic flow field. This is because the speed of sound in muscle is around 1500m/s or 4920 ft/s.

In comparison to aerodynamic models, peters, et al have developed a drag model that accounts for the tearing of the tissue. The equation of motion is given by: -M dV/dt = ½ pV2 ACd+ 1/2p (aU)2 ACD

Or it can be written in terms of distance traveled as:

-m dV/dx= 1/2pACd[V2+ (aU)2]

Where:

M is the mass of the projectileV is its velocity

P is the density of the tissue

A is the presented area of the projectile (the presented area is different than the cross sectional area.)

Cd is the projectile drag coefficient

X is the distance the projectile has progressed into the tissuea is a modification to CD

U is a characteristic velocity of the tissue

Looking at the second equation, we can see that if we exclude the second term on the right hand side, we get the classic equation for aerodynamic drag (assuming, of course, that the area is a cross-sectional area, S, of the projectile). The second term accounts for the energy loss associated with the tearing of the tissue and its movement away from the projectile.

If a projectile has features that would cause it to expand upon impact with the more dense human tissue, it will cause greater trauma. These types of bullets were mentioned as hollow point and slit-jacketed bullets. The opening of the hollow point or jacket allows more of the projectile’s energy to be transferred to the body and the flatter surface directs the flow of the tissue in a more radial direction. If a bullet is unstable in the body and it tumbles, there is more surface area presented for the body to slow the projectile down and thus more energy would be expended on the body. A greater amount of cavitation will occur as well due to the greater radial flow of the tissue. Depending on whether this expansion happens at the entrance to the body, the exit, or somewhere in between, the wound would be affected either by having a larger cavity at the entrance, in the middle, or upon exit. This would explain why sometimes small caliber wounding looks to be horrendous- it’s a byproduct of a bullet’s instability, however this is not a guaranteed result 100% the time, and again, it also depends on the materials used in the bullet.

Again it’s worth noting that the design of bullets used by the ar-15 (223 remington/5.56 nato) are not necessarily designed to tumble or yaw, but can be affected that way due to the lack of mass and potential instability inherent in a smaller caliber round, meaning due to physics, fluid dynamics, etc. The bullet may be prone to tumbling depending on what type of tissue it comes into contact with, and that results of testing on gel, or animals, dead or otherwise, will not necessarily be an analogue and indicative of what happens when a human is shot with the same bullet, at the same speed, angle, etc.

With either the 55 or 62-gr. full metal-jacketed military bullet in 5.56 nato, for instance, the average distance of penetration before significant yaw develops is 12 cm, whereas The 7.62 × 51 cartridge (.308) with a full metal-jacketed bullet begins to yaw after 15 cm of penetration. So while the military M-16 version of the 5.56 nato round will tumble sooner, the larger diameter bullet will also tumble, or yaw. In both cases the yaw progresses until the bullet ends up traveling base forward, resulting in a larger exit wound should the bullet exit the target body. Physical observations of wounds based on forensic science:

The following are just some notes included for the casual reader or viewer who might be trying to tie together some of the physics mentioned earlier to forensics literature.The range at which a target is fired upon affects the nature of the wound. Following Dodd, I’ll define the following distances from the muzzle:

Type of Contact:

a. hard contact –muzzle pressed into flesh

b. contact- muzzle touching flesh

2) near contact- muzzle very close to the flesh

3) intermediate (about 3 feet for rifles, or 2-3 barrel lengths for handguns)

4) distant.

One of the things that the media and people who buy into politically based definitions of a firearm is that the AR-15 is somehow a military grade weapon. And while this is completely false, and the gun itself has been modified prior to ever being released to the public, this misnomer still exists. But since this persists, I want to cover what wounding looks like in terms of what the military would encounter most. The distant range is the most encountered by the military in their operations.

As stated above, we can consider the intermediate range to be 3 feet for rifles. In most distant range cases, there will only be a bullet hole present. It is possible to observe an abrasion or grease rim. A low velocity (subsonic) impact may exhibit a neat hole and a well-defined abrasion rim, while a high velocity (super-sonic) impact may exhibit a hole with radiating splits. The presence of the abrasion rim is largely dependent on the aerodynamic shape of the bullet. A pointier bullet, such as a boat tail hollow point or FMJ, yields less abrasion rim, while a blunter bullet yields more abrasion rim.Since in military operations one is more likely to encounter distant range and perhaps intermediate range wounding, I want to discuss the behavior of different weapon type wounding in these situations.

At these ranges, round nose bullets typically will exhibit less well defined entry holes and will bruise the target more. With handgun wounds at intermediate ranges, bullets sometimes (but not always) mushroom due to their construction of softer core material. Handgun wounds at distant range usually exhibit circular holes with small tears.

With a .22 rimfire cartridge wound at intermediate range, for example, it is generally observed that: if a target is shot in the head with a .22 short, the bullet rarely exits the skull, while the same location impacted with a .22 long or magnum may exhibit secondary skull fractures. At distant range, holes caused by .22 rimfire cartridges are icepick like.Hollow points in this caliber generally do not generally mushroom unless they hit bone, and even then, they often just penetrate into it. If they were to mushroom, it is more likely to occur with .22long or .22 magnum.

Musket balls and canister shots rarely exit the body, and when they do, the exit wound is large. In most cases, the entry wound is about the size of the ball, but the wound track is usually larger than the ball. Minie balls are far more damaging than round balls, and, interestingly enough (for those who insist that the 2nd amendment only applies to black powder guns) are even more damaging than full metal jacketed bullets.

Centerfire rifle wounds at the intermediate range can injure organs not in the direct path due to shock effects (hydrostatic shock,) though this is still debated in the ballistics community. These cartridges create a very large temporary cavity due to the velocities involved. Occasionally clothing imprints are found on the entry area. At a distant range, these cartridges exhibit behavior that is very similar to that at intermediate range. The entrance wound will usually be about 2 to three times the bullet diameter, with the exit wounds usually being larger than the entry wound. Again, those who suggest that the 223 is a particularly devastating round is being disingenuous at best, because of this fact.

Again, centerfire rifles usually produce an exit wound that is larger than the entry wound.

Notes on Physiological incapacitation: centerfire rifle vs. handgun.

On a physiological level, the location a victim is hit will have a great deal of influence on the incapacitating effect of the projectile. Nearly immediate incapacitation will occur when the impact is in the region between the victim’s eyebrow, and sternum (from the eyebrow to the bottom of the ribcage). With a powerful cartridge, the impact to in the pelvic region will cause a target to collapse. This is because the pelvis is the main load bearing region of the body. An impact to the stomach area usually takes the longest time for incapacitation.

With a handgun, unless the brainstem or upper spine is hit, it usually takes about 5 seconds to incapacitate the victim. Less time is possible, but this is usually due to the psychological state or medical particulars of the victim.

Back to tissue effects: As mentioned earlier, the behavior of the projectile will be affected by the different tissue types and densities. Different tissue types are similarly affected by the tissue differently buy the projectile based on their physical properties (shape, materials, etc.) Bones are the hardest materials in the body. They behave somewhat like multilayer composites. The skull has some unique behavior because of its makeup and geometry.

Internal organs have very different properties from one another and therefore respond differently to bullet impacts. The effects will vary depending on the organ affected and the velocity of the projectile.

With a bullet with a subsonic velocity, large holes with minimal cavitation occur (the 9mm in the example shown by 60 minutes, for instance.) there will normally be a small, neat hole, with minimal cavitation. In the case of supersonic bullets (like those from centerfire rifles), generally large holes with large temporary cavities are observed. Bullet breakup is also a major factor in wounding. When, where, and how the projectile breaks up makes a difference in wound severity.

  • Brain penetrations, for instance, usually result in immediate collapse of the victim. The bullet path can result in catastrophic damage, due to the brain’s sensitive makeup. A large temporary cavity may cause the skull to explode, or the brain to be ejected from the skull. Impact in the frontal lobe may not cause immediate incapacitation.

  • Impacts to the spinal cord usually result in impairment of the victim’s motor skills. Possible complete immobilization of the victim can occur depending on the impact site and whether the spinal cord is severed.

  • Penetrations of the heart or major arteries are generally not immediately fatal. There will be major internal or external loss of blood from the victim.

  • Impacts to the liver vary from victim to victim. This is generally because the liver tissue of each individual can vary in elasticity, and hardness due to the victims’ health. If a victim has hardening of the liver, for instance, it may actually spall (break into smaller pieces.) death of the victim usually results from bleeding and as a result, isn’t instantaneous. Higher velocity round impacts to the liver are far more catastrophic. A human liver generally has a specific gravity between 1.02 and 1.04 (Carlucci) so it is close to water in density. The liver is not elastic and thus results in large areas of bullet destruction. Because of this inelasticity, the size of the permanent cavity is on the order of the temporary cavity (i.e. it stays big, and doesn’t shrink as in other wounding)Impacts to the stomach, gall bladder, and intestines are similar to the liver.

These organs are known as hollow viscera. Death from a bullet penetration in these areas usually results from bleeding and therefore is not immediate. More damage results if the body is in the process of digestion because food will change the density of these organs.

  • The kidneys are similar in structure to the liver. Impacts to the kidneys are more survivable to the liver, however, because they contain fatty tissue, which may contain the resulting bleeding.

  • The bladder responds to bullet impacts in a matter similar to the stomach. More damage results if the bladder is full of urine. The bladder is protected to some degree by the pelvis, though spall from the pelvis may contribute to bladder damage (i.e. bone shrapnel)

  • The spleen is a solid organ, and death from spleen penetration usually comes about due to bleeding and as such, death is not immediate. High velocity projectiles may shatter the spleen completely.I mentioned muscle tissue earlier. It has a specific gravity between 1.01 and 1.02. as I mentioned, it is a cohesive material that resists bullet motion. There will usually only be a small region of bullet caused damage.

  • The elasticity of muscle tissue results in large temporary cavities and smaller permanent cavities.

  • Lungs are extremely different from all the other organs in the body. The lung penetrations are fairly survivable depending on the extent of the damage. If major blood vessles are ruptured, then blood occurs through suffocation. The specific gravity of the lung tissues is between 0.04 and 0.05. lung penetrations exhibit very small temporary cavitiy formation and a correspondingly small permanent cavity.

Incapacitation is probably the most controversial topic in all of the ballistics disciplines, so it’s not as cut and dry as some “experts” (television, youtube, or otherwise) try to make it seem, especially when in the context of a television spot, or video which is created to convey a certain narrative, or for entertainment purposes. We can safely say there is no one right answer about wounding. As I mentioned earlier, living beings are very complicated targets which are influenced by their psychological as well as physical state. Some of incapacitation theories I’ve tried to convey in this blog are:

  • Kinetic energy deposition theory

  • Hit location theory

  • Judicious mixture theory.

In all of these cases, it’s important to maintain a little common sense.

In the first two cases, the theory usually is coached as “all else being equal.” In reality, all things are never equal. No one theory can explain anything, that’s why it’s a theory, and referred to in a theoretical sense, although people struggle to define one thing that can compare their favorite bullet to all others… the elusive silver bullet. In dealing with centerfire rifles, the severity of the wound is determined to a great degree by the amount of kinetic energy lost by a bullet in the body. The intermediate cartridges used in true assault rifles such as the m-16 or military ak-47 possess significantly less kinetic energy than traditional military cartridges as well as rifle cartridges designed for hunting. Therefore, it is impossible for an intermediate-power rifle cartridge to produce severer injuries than a full-power rifle cartridge, all other factors being equal. (dimiao)

The kinetic energy disposition theory states that a projectiles impact velocity has the greatest impact on wound severity-all things being equal. Damage to the target results from laceration followed by bleeding in addition to tissue disruption and crushing. Shot location is important-so all things are not really equal.This theory goes on to dictate that a projectile that deposits more of it’s kinetic energy in the target will cause more damage, thus, if a projectile stays in it the body, it has therefore deposited all of it’s kinetic energy.

Fackler, in his book wound ballistics, a review of common misconceptions, disagrees with this.

The shot statement location was incorporated due to the different organs’ ability to absorb kinetic energy. This comes about because of the organs’ density and tissue coheision. Organ density affects the ability of tissue to absorb kinetic energy- more dense means more likely to be damaged. Cohesiveness of tissue is the ability to dissipate kinetic energy by stretching. Dimaio attributes kinetic energy loss to four factors:

1) the initial kinetic energy of the projectile 2) the yaw of the projectile at impact 3) the caliber and structure of the projectile 4) the tissue properties along the projectile path. The greater the initial kinetic energy at impact, the more there is available to deposit into the target. The greater the propensity for deformation of the projectile and or break up. If it does not deform, too much energy may be viewed as undesirable depending on the application, as the bullet would pass through the target all together. However, the target may still be incapacitated to some degree, and may bleed to death, but this takes time.

A pass through certainly deposits less energy, however there was more to begin with, so Carlucci says this may be a circular argument.

More yaw at impact means that it is more difficult to penetrate the target; if the projectile does penetrate the body, then the hole will be bigger and the projectile will drag down faster- that means more kinetic energy will be deposited in a target.

Larger caliber and or blunter projectiles deposit more kinetic energy in a target because they have greater drag. Bullets that expand deposit more kinetic energy in a target in this way. This is why there are some that expand by using a hollow point, slit, or lower core hardness, etc.

Higher drag projectiles deposit more energy into a target.

Projectiles that fragment deposit more kinetic energy into a target as well. Tissue properties are another factor in this particular theory. Greater density tissue would allow more kinetic tissue to be deposited by the bullet along the path of travel. Greater tissue strength would allow more kinetic energy to be absorbed by the body. Greater elasticity in the tissue would allow more kinetic energy to be dissipated. Fackler states that projectiles with the same kinetic energy that impact different locations will have completely different results. This seems to be supported by at least parts of DiMaio’s theory.

DiMaio has a theory which also states that the same amount of damage occurs when some critical impact velocity is achieved. According to his theory, different projectile types have different critical velocities. For FMJ projectiles and steel balls for instance, the critical velocity is 800 and 900 m/s. for soft or hollow points, the critical velocity is much less, at 457 and 610 m/s

All in all, there are several theories as to why bullets behave the way they do in the body, and why they wound the way they do. conclusion:

So what’s the end point and ultimate idea that I wish to convey to you, the reader, about this topic, after such an exhaustive show? Simply that it’s very complex (as evidenced by the ‘condensed’ version I’ve tried to lay out here), and cannot be condensed into a 15 minute television spot, and hope to be all inclusive or completely objective in what it’s looking at, and further, that the viewer of said programs really needs to take these things, as well as videos on the internet, as it’s not so cut an dry, so I encourage you to do your due diligence, do your research and take TV special reports with a grain of salt when you watch them.

Have a happy new year. stay safe, and happy shooting

Ken Kraushaar is a gunsmith and IFSA certified firearms specialist living and working out of Sonoma County, CA. Ken has over 30 years of shooting experience.


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notes on overpenetration

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