Requested post on “stopping power” of firearms:
if you attempt to purchase a firearm for hunting or defense, be prepared to deal with a lot of information on the relative merits of different calibers and cartridges. Because weapons are owned and kept silent much more often than they are discharged in defense (by orders of magnitude) and because its frowned upon to perform injurious experiments on humans and animals, most of this information is not based on experience or historical performance. Even attempts to create some sort of empirical basis are subject to methodological errors. So basically you have to employ rigorous epistemology when you discuss the subject. Dont take my word for this, you wont have confidence until you understand it yourself.
Another caveat is that lethality is only tangential to our discussion for moral and legal reasons. If you shoot someone in defense of yourself or another, in order to prevent aggressive violence, you had better shoot with the intent of incapacitating the aggressor. Dont shoot to kill, dont shoot to wound, dont fire warning shots. Shoot with the intent to stop the aggressor as quickly as possible. This is appropriate use of deadly force, and it follows from the nature of the conflict. The only reason your use of violence is legitimate is because of the threat posed towards you by the aggressor. You may not attempt to “punish” the aggressor by killing him, but you may employ deadly force in order to stop the threat. I hope thats clear, and I hope thats something that all of you will remember if the worst should happen.
so what stops a human or animal aggressor? The wound. Theres a bunch of theories about stopping power that focus on the characteristics of the projectile, but thats a distraction. Human physical action (threatening or aggressive behavior) is dependent on physiological factors, as in a guy who doesnt have enough blood pressure to stand up isnt going to pursue you. What stops an aggressor? The wounds that you inflict on him. I hope this doesnt sound condescending, its a premise for the subsequent discussion.
there are three basic rapid failure modes for humans and other animals: electrical, hydraulic, and mechanical. If the nervous system is damaged to the extent that the brain does not send signals to the muscles, the aggressor is not going to move, thats electrical failure. If the person’s blood supply is inadequate to the task of aggression, then he isnt aggressing against you, you stopped him. Thats hydraulic failure. And if the musculoskeletal system doesnt have the physical integrity to aggress (a shattered pelvis for example), thats mechanical failure. Theres other failure modes but I dont think anyone is shooting out somebody’s eyes intentionally in a lethal force situation so they can cause epistemological failure modes. That would probably be electrical, because nervous system damage is electrica failure.
Electrical incapacitation is the fastest, the targets (brain and spinal cord) are also small and hard to hit. I mention spinal cord for completeness but it isnt something that people are usually trained to target. This is also the most lethal. Exsanguination (blood loss) is slower, but also easier to achieve because if you break the skin, you get blood and even extremities have vascular regions (femoral artery) that can cause rapid loss of blood leading to incapacitation and death if not treated. However this is on the order of minutes, so depending on the aggressor’s psychological and pharmacological state, he may remain a threat for quite some time. If you have ever been in a fistfight, you know that minutes are like hours, so a minute in a firefight must be like a day lol. Now mechanical incapacitation is the dark horse here, it is a tertiary option if you are in some deep shit, like the guy is too far away for a headshot and he is wearing body armor covering his center of mass (which is your default position for aiming is, for multiple reasons) so you shoot him in the pelvis so he stops walking towards you firing, and if he is still a threat you shoot him in the head (which should be easier because his pelvis just disintegrated). How easy is it to shatter a pelvis with small arms fire? I dont know, its up for debate. The pelvic area is a vascular region and the pelvis is one of the strongest bones in the body, its actually an ellipse (sort of) so multiple rounds are reccommended. Its supposed to be really really painful to have abroken pelvis and its a structural member so its basically the main mechanical target. Knees are smaller than the cns target and they are probably moving faster anyway.
ok so we established our goal (incapacitation), we established our rules of engagement (the prevention or interruption of imminent or current aggressive violence), and we established our desired failure modes (electrical, hydraulic, or mechanical). What means do we use to achieve incapacitation as a result of electrical, hydraulic, or mech failure? Gunshot wounds. The gunshot has a number of effects on the aggressor, and the multitude of variables makes many of these effects difficult to predict. I will list and expound on these effects in decreasing order of importance, according to my opinion.
the major effect is the permanent crush cavity, which is a technical term for the path of severed tissue that has been destroyed by the round. This is the primary means of achieving incapacitation. If parts of the reptile brain are destroyed, then basic motor functions cease and the aggressor no longer acts to pose a threat (his corpse might contain a bomb but thats beyond the scope of this discussion). Its possible to sustain brain damage and continue to function, this is why people are taught to shoot at the area of the brain above the plane intersecting the nostrils and below the plane bisecting the eyes. A crush cavity that intersects blood vessels leads to blood loss. A crush cavity causes mechanical damage, impairing the function of those body parts (please dont try to shoot the gun out of someone’s hands). A crush cavity is like a stab wound from long range. It severs tissue, and that is the primary mode of incapacitation because of its mechanical certainty.
The transference of kinetic energy from the massive, rapidly moving projectile to the tissue also has two secondary effects that are sometimes significant. The first of these is a temporary crush cavity, which represents the elastic tissue distorting away from the path of the round and returning to its original location. This usually doesnt cause permanent damage or contribute to incapacitation (as far as we know) except in circumstances that involve another projectile creating another crush cavity. This is what frangible rounds do (they also refrain from penetrating through things like drywall, for the safety of noncombatants and liability limitation. I cant tell you how well they do). The fragments cut through the compressed tissue like if you folded up a piece of paper and cut it wit scissors. You fold a paper in half twice and cut a 1" slot, unfold it and you have 4" of severed paper. Thats what happens to tissue, and the temporary crush cavity facilitates more severe wounds, resulting in more severed blood vessels.
The second of these kinetic energy effects is called hydrostatic shock, and this is where the b starts to s. You guys know that fluids in a container have significant inertial properties, such that vehicles with large tanks, like trucks or ships, need to have baffles to slow and disrupt the movement of fluids. Well the human body is mostly fluid, and that fluid has the tendency of transmitting KE from the path of the projectile to other tissues and organs. People love to talk about “energy transfer” and such when it comes to calibers, but this is oftentimes wishful thinking. Nobody really knows because of aforesaid methodological and epistemological difficulties, but in my opinion rounds have to be moving pretty fast to make this happen in a nontrivial way. This is because energy equals mass times velocity squared. My brief physics refresher prior to typing this post suggests that the statement “ke=m*(v*v)” is an oversimplification but no one should quibble unless you have a problem with my assertion that an increase in velocity produces disproportionately larger energy than a similar increase in mass. Thats the important part of the theory as to why hydrostatic shock is difficult to achieve from pistol rounds (at least reliably, dont badger me with anecdotes). The answer I was taught is that unless your rounds have a muzzle velocity of around 2,700 feet per second, theyre not going to create incapacitating shock waves in the enemy. Furthermore, if hydrostatic shock was reliable and effective at inducing failure modes in humans, you wouldnt see things like guys getting hit in the torso a bunch of times and surviving. Hydrostatic shock exists, and has nontrivial incapacitation effects, but its not reliable to induce as of yet.
the fourth significant effect of KE projectile weapons that we will discuss is muzzle blast effects. We know that firearms work because propellant deflagrates, producing hot, expanding gas that pushes the projectile down the barrel and towards the target. This hot gas creates noise, flash, and a pressure wave, and if you are standing near the muzzle when an unsuppressed firearm is discharged, you will experience at least two of these (the muzzle flash might not be visible because of the firearm or because its daylight, but if you cant feel the pressure then you arent really “near” the muzzle). In close range shootings, these phenomena have nontrivial effects. For instance, one of the attempts to empirically study the effectiveness of calibers, in the 1980s some guys collected data on a bunch of law enforcement shootings, trying to find what round/caliber was most reliable at achieving a one-shot stop. They published data (that was influential at the time) basically saying that .357 magnum 125 grain jacketed hollowpoint rounds produced a one-shot stop like 95% of the time. Well science moves on, and the analysis of the data that I am partial to observes that the data they used contained a disproportionate amount of low-light, close range shootings. So, muzzle blast from a 4" barrel .357 magnum (which is the longest barrel length that you could expect to see a law enforcement officer use in a revolver) in low light is like a 6 foot expanding fireball (think dhalsim from street fighter doing yoga flame) and the hot gas displaces air. So a guy gets shot once, at close range, in low light, he actually has multiple effects working together: theres the one-third inch diameter, 12 inch deep stab wound in his body; theres the KE delivery, which likely isnt enough for bona fide hydrostatic shock but would be kind of like getting punched; there is the fireball effect; and when all of this causes him to take a deep breath (because he is surprised and had the wind knocked out of him) he breathes in hot gas with low oxygen content. I would fall down too. After all this has happened, including the impact on the ground (wanna bet he hit his head on the floor?), most people probably dont have the physical capacity or wherewithal to get back up and fight while bleeding from a .357 magnum gsw.
you’ll note that I only recently began talking about individual calibers, and that was only for purposes of illustration. This is because, as I said above, the factors affecting stopping power are related to the wound, not the weapon per se. Now its time to talk about calibers. Now considering our two primary means of incapacitation (electrical and hydraulic), is there any reason why you couldnt defend yourself with a .22 lr? Of course not, you can cause CNS damage and exsanguination with a .22. Knowing what we know now, is it possible to hit someone with a .50 bmg and not remove the threat? Yes, shoot someone in the lower extremity with a .50 and its still conceivable that they could aim and fire upon you. So you see that shot placement is always more important than the energetic and wounding characteristics of the caliber/round combination.
Of course, larger wounds destroy more tissue and facilitate more rapid blood loss. More wounds also cause more tissue damage and facilitate more rapid blood loss, so youre in a tradeoff between larger, more powerful rounds and higher ammunition capacity. This is a decision that has few clear-cut answers, as firearm selection is a intensely personal decision. People should own and carry weapons that they feel confident in using, meaning that ultimately the question has subjective answers (within objective limitations, i.e. one should carry a weapon that is reliable and accurate).
the fabrique national five-seven pistol in 5.7 mm was an attempt to achieve hydrostatic shock from a pistol. To my knowledge, the terminal ballistics experts dont consider it to be successful at this goal. I tend to lean towards their opinion, as muzzle velocity is just over 2100 fps, below our arbitrary floor of 2700.
I alluded to this above, frequently people attempt to quantify stopping power with formulas or metrics like kinetic energy. These metrics are good for comparative purposes, but the numbers describing the dimensions and energy state of a projectile are not what stops aggressors. The wounds imparted to these individuals are what stops them. This is why a moving car has way more KE than a rifle round, but one will break your bones and knock you down, and the other will pierce your heart and kill you.
the worst examples of the “quantification of incapacitation” are sometimes the guys who think anything less than a .45 is designed for women and mental incompetents. Any time they see a weapon that isnt a 1911, they turn up their noses and ask when youre going to get a “real gun.” and if its bore measures under .4", be prepared to explain what you plan to do after you empty your magazine into a perp and he laughs at you. If its less than a 9mm, prepare to have your manhood questioned (even if youre a woman). You probably shouldnt even let these guys know that you own a .22, because they dont do much shooting so appealing to low cost ammunition will get you nowhere. They have a fascinating theory of physics that involves momentum transfer and bullets that accelerate between the muzzle and the target. A .45 will stop anything in north america, and if its a 1911 in .45, you can take herds of tyrannosaurus rex with ease, mozambique style (a mozambique drill is a type of failure-to-stop drill where you shoot two rounds in the chest and one round in the head). If these guys ever do shoot anyone, they will be surprised when the perp doesnt fly backwards, flip over twice, and dent the wall they impact. This population heavily overlaps the beer-can patriots, they hate us for our freedoms, turn their country to glass type population. Just tell them you carry a 9mm because you like to exercise your rights but you dont want to hurt anyone, they will “understand”.
Mr. Chairman, I yield the balance of my time to the members for question-and-answer.
