Energy: Don’t Sweat It!

45ACPFMJSubsoniccropped

The views expressed in this opinion article are those of the author, not TheFirearmBlog.com, or anyone else.

Energy is a pretty hot quantity in the firearms industry: Guns in new calibers are marketed by how much more energy they produce than the competition, prospective owners weigh the benefits and drawbacks of rifles firing more expensive but more powerful ammunition, and everyone knows a deer hunter that brings out an anti-tank rifle every season.

Using appropriately powerful ammunition for a given task is important, of course. However, thanks to the marketing efforts of companies trying to differentiate themselves by offering rifles chambered in new calibers, the importance of energy with regards to terminal effect – especially in military or self-protection applications, has been inflated. Further, some advertisements may lead one to believe that energy is the end of the story regarding terminal effect. Proudly advertised figures of muzzle energy or energy retained at range in some cases mask other shortcomings of new ammunition. I don’t intend for this op-ed to be very long; I’m only going to explore a couple of aspects of terminal effect pertaining to energy that some TFB readers might not have thought about before.

First, it’s important to remember that the foremost characteristic that should be on your mind when selecting new ammunition is bullet design. A poorly chosen bullet in a powerful caliber will more surely lead to frustration and failure than a marginal caliber packing the right payload. A good example of this is the success and failure some hunters had in the late 1930s and early ’40s with the then-new high velocity .220 Swift. Initial use by experienced hunters produced excellent results, but subsequent failures of the round with early soft-point bullets pushed too fast cost the caliber much of its good reputation. Today, medium sized game such as hogs are routinely culled with much less powerful 5.56mm or .223 caliber rifles firing much more appropriate, heavier projectiles launched at more modest velocities.

.223/5.56mm is a popular hog hunting round, and – with proper bullet selection – works very well on medium sized game if the hunter does his part.

A good example of how energy does not tell the whole story is given by a comparison between two subsonic rounds used in suppressed applications: The .45 ACP, which has been in use for this purpose since the 1940s at least, and the .300 AAC Blackout – a newcomer to the suppressed rifle game. On the surface, and in AAC promotional material, the .300 Blackout is decidedly superior to the .45 ACP; with its long, slender high sectional density bullets it produces 30-35% more energy than .45 ACP over its effective range. However, this doesn’t tell the whole story. When their terminal effect in gelatin is compared, it’s difficult to tell the difference for the first foot or two of bullet travel.

.300BLK220OTMSubsonic

.300 AAC Blackout 220 grain subsonic OTM at 1,000 ft/s produces a long, stable wound channel without upset within the first 24″. Source: TWANGnBANG’s YouTube channel, https://www.youtube.com/watch?v=i1Q7xRmZAtk

45ACPFMJSubsonic

.45 ACP 230 grain hardball, at 780 ft/s, creates a very similar wound channel to the .300 AAC Blackout, despite producing three-quarters the muzzle energy. A human foe hit with either round would most likely have a similarly unpleasant experience. Source: BrassFetcher’s YouTube channel, https://www.youtube.com/watch?v=3G-txVKnVjY

 

A further example of this can be found in another BrassFetcher video, comparing different carbine cartridges with each other. Despite the larger caliber cartridges’ greater muzzle energy than 5.56mm, for the first half of projectile travel, energy deposition and temporary cavitation look nearly identical. This early segment of travel is the most important when discussing terminal effectiveness against human foes:

Even though the first three rounds tested have identically constructed bullets, the 5.56mm still dumps the overwhelming majority of its energy earlier, while the latter two rounds “save” more of their energy for later in their travel. This is because of the former’s lower sectional density and higher velocity. Against human targets, we being a relatively thin-bodied species, it would be difficult to distinguish the effects of all three rounds, while against wider-bodied animals one might see a dramatic difference in their effectiveness.

Thus, the energy a round produces at a given range is demonstrated to only inform an “energy budget”, i.e., the maximum amount of expendable energy it has to offer. Two cartridges producing very different levels of energy may have a similar effect on a target, if bullet construction and velocity permit. Conversely, two cartridges producing similar levels of energy could also have vastly different effects. What this means for the buyer is that the energy produced by a given cartridge-rifle system only matters inasmuch as it provides enough energy budget for a given task, with available projectiles. For home defense, as an example, it may be more prudent to buy a weapon chambered for a weaker round, but that has superior bullet selection and ammunition availability, than to buy one in a more powerful, but less flexible chambering.

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The author uses a Glock handgun in 9mm, and an AR-15 pattern rifle in 5.56mm for home protection. Despite both being on the lower end of the power spectrum in their respective classes, the author has chosen effective, inexpensive rounds in those calibers, and does not worry about being unable to stop a threat.

For some readers this article will tell them nothing new – they’ve known for years to use enough gun, and no more. For others, including those I’ve bumped into in virtual and real life, I am hoping this article provides enough for them to examine their needs and make an economical and effective decision regarding their next purchase.



Nathaniel F

Nathaniel is a history enthusiast and firearms hobbyist whose primary interest lies in military small arms technological developments beginning with the smokeless powder era. In addition to contributing to The Firearm Blog, he runs 196,800 Revolutions Per Minute, a blog devoted to modern small arms design and theory. He can be reached via email at nathaniel.f@staff.thefirearmblog.com.


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  • allannon

    It doesn’t seem controversial enough to me to need a disclaimer, especially since it’s addressing most specifically hunting and defense use (soft targets).

    It’s all about choosing the right rounds. I’ve taken whitetail out around 500yd with a .243, and seen someone nearly lose one at 200yd with a .300 win mag because the bullet didn’t deploy optimally. Conversely, I don’t think I’d take a shot at a whitetail at 700yd with a .243, but I’d be much less hesitant (subject to my own marksmanship) with the .300.

    • How controversial the topic is seems to depend a lot on who you’re talking to. Further, I feel it’s important to not falsely represent others.

  • Marc

    Worst part of an energy discussion is when the guy you’re arguing with multiplies mass with velocity to show how much more energy his favorite cartridge has.

    • Pseudodeus

      Momentum isn’t unimportant. But yeah, physics failures are tragically common.

        • AlDeLarge

          “When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.”

          Whoever wrote that article never took a physics class. The gun and bullet have equal amounts of momentum. Take a ten pound weight and drop it in your hand from a few inches. No problem right? Now attach it to a needle and drop it in your hand. Big problem. Same momentum, but different frontal area. It’s the same thing with a bullet and gun.

          Momentum is the key metric in general collision physics. In inelastic collisions, like this, it’s momentum/frontal area. This is why your .45 ACP vs. .300 AAC test went the way it did. The .45 has 64% of the energy of the .300, but 82% of the momentum. Your results reflect the smaller difference in momentum.

          Physics problems
          http://tuhsphysics.ttsd.k12.or.us/Tutorial/NewIBPS/COMQ/COMQ.htm
          http://www.physicsforums.com/showthread.php?t=281104

          • With respect, sir, that’s not correct at all.

            Consider another example: Let’s say you took a 7lb bolt action .223″ caliber rifle, and affixed to the buttplate a long needle, .22″ in diameter. Then you set the needle against ballistic gelatin, and fired the rifle into another block of ballistic gelatin set in front of it. Being a good experimental scientist, you took high speed footage of both impacts. According to your theory where momentum is dominant, the temporary cavities of both the needle and the bullet entering tissue should be the same, since in it effectiveness is a function of frontal area and momentum.

            Of course, we know that given a propellant weight of 30.5 grains, gas velocity of 4,500 ft/s, bullet weight of 62 grains, and muzzle velocity of 3,100 ft/s, that the needle going the other way will have a velocity of 6.7 ft/s, or about 4.6 miles per hour. In other words, the real question is, do you think it is humane to hunt coyotes by briskly walking at them with a pilum?

          • AlDeLarge

            I said momentum is the key metric in collision physics, not the only metric in bullet impact. The article you linked discounts it entirely by claiming that if it had any relevance, the butt of a rifle would be deadly when you fire a rifle. That is nonsense.

          • You seem to be misunderstanding me, which is probably my fault. I did not say that the momentum of a projectile implies zero effect on a target during impact, rather that, to rephrase, momentum is irrelevant when determining the “stopping power” of normal small arms projectiles against unarmored human targets.

            It’s unfortunate that the term “terminal effectiveness” is a sort of euphemism for “stopping power”, which itself is full of wrong implications. I should consider editing the article to avoid the use of “terminal effect” in favor of something clearer.

          • AlDeLarge

            It has a bigger role than you think. Remember, momentum is measured in lb ft/s.

            A bullet going 780 fps travels a foot in 0.0012 seconds. 0.8 lb ft/s expended over 0.0012 seconds is 667 lbs. That’s a lot of force.

            A bullet going 1000 fps travels a foot in 0.001 seconds. 0.8 lb ft/s expended over 0.001 seconds is 800 lbs. That’s a lot of force.

            How long would it take for your 160 lbs and a half inch dowel example take to stop against ballistic gel, in an otherwise frictionless environment? 0.8 lb ft/s expended over 0.1 seconds is 8 lbs. That’s not so much force.

          • I’m still not sure what your contention is here. I never said force was irrelevant to terminal effectiveness. Neither did I say mass or velocity were irrelevant.

            All of those examples have similar momentum, but different force. Doesn’t that prove it’s their force, not their momentum, that is relevant?

          • AlDeLarge

            The momentum predicts the final forces better than any other basic measurement, far better than kinetic energy. It places an exponential importance to velocity which doesn’t translate to exponential force.

            Those were not the best examples for the two bullets, considering that if they were the same caliber, they would take the same amount of time to stop, and transfer momentum. The resulting force would be the same. I don’t really have a good way to calculate that time, so I just used f/s inverted, s/f. A poor choice on my part. They do show why the extremes are so different though.

            When you’re comparing most bullets, you’re dealing with similar magnitudes of size, speed, and mass. Momentum/frontal area is a combination of size, speed, and mass. Within reasonable ranges, momentum is your best predictor. Look at 9mm vs .45 in gel. The 9mm has a bit more energy than a .45, but the .45 has significantly more momentum. The .45 does significantly more damage to the gel. The difference in damage is very similar to the difference in momentum.

            It’s useless for predicting temporary cavities, but if you sit down with a calculator and scaled gel cross-sections, I think you’ll be surprised when you start comparing momentum to permanent damage.

          • Alright, I finally understand what you’re getting at. I will make four comments:

            First, this seems most relevant to medical treatment of gunshot wounds, and less relevant to the ability of certain projectile to effect a stop on a target.

            -An aside, “stopping power” is a very clunky and inaccurate term, “terminal effectiveness” is too easy to confuse with the broader subject of terminal ballistics (which includes things like armor penetration), and “energy deposition” is (unfairly) controversial. Maybe another term is needed, or maybe neat ideas like stopping power don’t really gel well with the reality of the subject.

            Second, against human targets, a round that might create a long permanent cavity (i.e., one that doesn’t deposit its energy quickly, like an FMJ handgun round) through an infinitely long block of ballistics gel can only create a wound channel as long as the cross-section of tissue it hits.

            Third, your method of approximation only works for projectiles within a narrow band that behave predictably (and “works” is relative – I would contend your assessment that .45 does significantly more damage to gel than 9mm). In my opinion, that makes the approximation not very useful. If it cannot be used to predict an unknown, and only can be used to reinforce a known or a suspicion, then it is not very useful. Essentially, it sounds like you have created a tool that looks like math, but actually only reinforces your confirmation bias.

            Fourth, it’s a little strange to claim that I must “never have taken a physics class”, based on my rejection of your rule of thumb.

          • AlDeLarge

            If you have taken a physics class, the only thing you learned were some formulas. You don’t understand what you’re talking about. This is proven science not my “pet theory.” Neither is it a crackpot theory, like your assertion that momentum is irrelevant to [whatever you finally decide to call it.] You can’t even define what you say it doesn’t affect.

            No matter how you try to convince yourself otherwise, the size of the wound is a key component to all those things you say you’re not talking about. So when you finally find something that doesn’t have anything to do with wound size, then maybe you can claim momentum has nothing to do with that.

            I’m sorry you think the range of “most bullets” is too narrow for comparing most bullets, but that’s your problem. I’m talking about comparing bullets and how much damage they do, not emotional states, or shooting ability, or people on skates with wood dowels, or how your laces are tied, bullets and their damage.

            If you’re going to talk about choosing a round for certain purpose, talk about the rounds. You have two articles we’re discussing. This one dismisses kinetic energy as an accurate predictor of terminal bullet performance, and the one dismissing momentum. The former is a successful, pseudo scientific demonstration of kinetic energy’s overvaluing of velocity. It also demonstrates momentum’s role. The latter is babbling nonsense.

          • I do not think you have understood my arguments very well at all.

            You also seem to be having trouble connecting valid formulas for physical phenomena to their proper applications.

          • AlDeLarge

            I don’t think you understand either of our arguments.

          • I’ve been having a lot of trouble with yours, to be sure, a difficulty exacerbated by your insistence that I am some drooling moron (preposterous! I wiped all the drool off my beard hours ago!). I’m still puzzling over your counter-example. All three have the same order of magnitude momentum, but vastly different forces. Then you claim that momentum can inform the size of the permanent cavity, even though that’s very easily falsified.

            Now, force and momentum are related. No one said otherwise. However, force is equal to the rate at which momentum changes, there’s nothing about frontal area in there.

            You dismiss this by saying “oh, it only applies to bullets”. How so? Could you provide a model that proves there is an acceptable trendline fit within the relevant parameters? Why is it that no other ballistitician in the field to my knowledge uses this formula the way you do?

            The collision between a high speed projectile and tissue is a pretty complicated one. A transference of momentum is involved, yes, but that’s hardly the only factor. Everything from the jacket composition and integrity to the bullet’s shape is relevant.

            Now, you seem much more interested in insulting me and vaguely implying that you possess great expertise in the field, while demonstrating none of it, than actually discussing the topic and settling our disagreement. Fortunately, I’ve got a lot of posting stamina, so go right on ahead.

          • AlDeLarge

            I have no great expertise in the field. It’s just basic physics. It’s not that hard to understand. It takes less effort to understand than you’re putting into not understanding.

            more momentum = more damage
            less momentum = less damage

            If you need rigorous scientific experiments to understand that, you’re doing it wrong. Let me know when you come up with something more scientific than “If momentum mattered, the rifle but would be deadly.” (paraphrased) to prove your crackpot theory, and I’ll consider explaining, again, how what you’ve done on this article demonstrates the relevance of momentum.

            Quit saying that I’m claiming that momentum is the only factor. I never said it was. It’s an important factor, but not the only one. There’s some debate on exactly how important, but it’s complete and utter nonsense to say it’s not a factor at all.

            Since you won’t understand that two measurements in hundreds of pounds of force are more alike than a single-digit measurement, just try to forget the example I gave. That’s all it was meant to show.

            I think the arguments against bullets having enough momentum to translate to “knock-down” power (sometimes called “stopping power”) have thoroughly confused you. The “stopping power” in these arguments comes from Hollywood. It’s a myth. Bullets don’t make people fly backwards when they get shot.

            The other “stopping power” is real, vague, impossible to fully define, and a point of contention, but it’s real. Bullet mass and velocity are major factors in this, no matter how you approach it. Two measurements are a combination of mass and force, kinetic energy and momentum. Kinetic energy is one half mass times the square of the velocity. This places exponential importance on velocity. In terminal ballistics (collision physics) velocity does not have an exponential effect. This is what you’ve shown here.

            Momentum is simply mass times velocity. The .300 has 57% more kinetic energy than the .45, but only 22% more momentum. Which of these differences is more like what you see in your examples?

          • This simply isn’t correct, no matter how many times you say it. You’ve provided none of the evidence you point to as supporting your argument. Further, it’s a point of fact that your argument isn’t internally consistent (momentum always equals more damage, but that the rifle butt of a gun possesses more momentum than the bullet coming out of the muzzle doesn’t disprove that).

            Here are some documents, written by actual ballistiticians, to get you started on the right track:

            http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA240295 (link starts a download)

            https://docs.google.com/viewer?url=http://www.dtic.mil/dtic/tr/fulltext/u2/705381.pdf

            https://docs.google.com/viewer?url=http://www.dtic.mil/ndia/2005smallarms/tuesday/newill.pdf

          • AlDeLarge

            These documents you don’t understand, do not prove that momentum is irrelevant, and I never said it was the only factor.

            This is the first time I’ve been trolled by the author though, so there’s that.

          • You read them all so quickly? I’m impressed.

            Momentum has nothing to do with “stopping power”. Yes, it is an factor in the collision of two objects, but that is not the same thing. Frothing at me that I don’t understand physics, have never taken a physics class, and am a troll will not change this, and it certainly won’t convince me that you’re right.

          • AlDeLarge

            I’m kind of glad your “casual observer” supporter brought me back here. I just skimmed over this before:

            “apply math to them such that you get figures for momentum and energy, respectively, and you find that while momentum does not correlate to an empirically observed effect, and energy does,”

            Considering the subject of this article and the comparisons you gave, that is a very odd conclusion.

            “Two cartridges producing very different levels of energy may have a similar effect on a target, if bullet construction and velocity permit. Conversely, two cartridges producing similar levels of energy could also have vastly different effects.”

            See, that one’s true. Ammunition manufacturers give muzzle energy figures because they’re relevant to flight ballistics.

            Drag increases exponentially with velocity, just like kinetic energy. That’s also the real reason faster bullets lose more velocity (percentage and absolute) over the same distance. Even if you were to perform all the math you tried to describe, it would only be a pointless measurement of the effect, not the reason for it. A calculus professor might find it an interesting exercise, but there’s really no other point to it.

          • triple

            Firstly: I am going to assume you mean that muzzle velocity is relevant to external ballistics, because I don’t really see muzzle energy as being particularly useful to the calculation of firing solutions.

            Secondly: A projectile with greater momentum will penetrate deeper into a target, taking longer to transfer its energy to the target than a projectile with similar energy but less momentum would. Since the same energy is being transferred over a longer period of time, the peak of the energy transfer would be lower. As I am not a ballistician, nor a medical expert familiar with traumatic wounds, I cannot say for certain what this translates to in the real world, but I would imagine that having a higher energy spike is more beneficial than having a lower one.

            Thirdly: You sir, are a moron. Please leave and never come back.

          • AlDeLarge

            Being called a moron by someone who not only thinks mass is not part of trajectory calculation in air and that a shallow wound is more deadly than a deep wound, but also takes pride in said ignorance, is a compliment. Thank you.

          • triple

            Never mind physics classes, you need to take some reading comprehension classes. At no point did I say any of the things that you claim that I think. But please, do continue to publicly embarrass yourself.

          • AlDeLarge

            Don’t worry. I didn’t really think you believed what you said. You would’ve had to understand what you said, and if you understood it, you wouldn’t have written what you did. I brought up some things that would have to be true for your claims to be true.

          • I am not sure who you think you’re fooling here. It’s clear you’re being willfully obstinate, but you’re too boring to be a troll.

          • AlDeLarge

            I get emails when people who don’t know what they’re talking about, pretend they do and reply to my posts. It’s entertaining to tell them they’re clueless and see what they’ll pull out of their other orifice next.

          • Except that’s not what has happened here at all, is it? You’ve replied promptly and religiously, burning your own time to respond to my posts, while I’ve only replied in passing, when I deigned to. So then who is in control of this conversation, and who’s backpedaling to stay relevant?

          • AlDeLarge

            I see the problem. There’s this new electronic mail thing. People call it “email.” It’s used to send messages back and forth. When someone posts to a thread I’ve posted to, it comes to me in my email. I reply to it like any other email and it posts to the thread, or I can go to the page and reply. That’s what I was talking about when I said “I get emails when …” I thought maybe that’s how you were responding so quickly before, and you were answering very quickly for a while, but it appears I’ve over estimated you again.

            So, why’d you decide to stir this back up after two weeks? I’d all but forgotten about this. You really didn’t need to tell me you don’t understand email subscription or how distorted your memory gets after only two weeks.

          • You are having considerable difficulties understanding and internalizing other peoples’ posts. Further, you appear to have confused mass and energy here, as well. Why not take a break from the argument for a while, collect your thoughts, and come back later?

          • AlDeLarge

            For the slow:
            He said muzzle velocity was relevant to flight trajectory, but not muzzle energy. The difference between velocity and energy is mass. So if the velocity without mass is relevant and velocity with mass is irrelevant, mass must be irrelevant.

            Are you still confused and projecting on me?

          • I don’t think momentum is proportional to tissue penetration, actually.

            I agree with the rest, though.

          • Here’s another example problem. Let’s assume an average man gets shot with a .308 Winchester rifle, and has no exit wound (the bullet stops in the body). What was the effect on him in terms of momentum transfer? We’ll use a value of 150 grains for the weight of the bullet, and 2,800 ft/s as the muzzle velocity.

            We will also assume that the bullet stopped exactly at the rear of his torso (it wouldn’t), and also that his torso is perfectly round (it’s not), so from the circumference of 39.7 inches, we get a torso thickness of 12.6″.

            Now, the momentum of the bullet striking the target would be 8.3 N-s. For a 200lb man, this would cause him to begin moving backward at a velocity of 0.3 ft/s.

            Further, if it took the bullet 12.6″ to stop, that means it took it no less than 4.5 milliseconds for it to reach complete stop. (Actually it would take longer, since the bullet is slowing down the whole time, but this simplifies things.) That means the acceleration on the target could not be more than 66.7 ft/s^2, which is 2.19 gees acceleration.

            For comparison, an F-16 when brand new is rated for 9 gees.

            Thus, the momentum transferred to the target by a small arms projectile is minimal, and can be discounted entirely during an analysis of projectile terminal effect.

          • AlDeLarge

            So, did you miss the part where I said the Hollywood version of “stopping power” is a myth, or do you not understand you only disproved the Hollywood version?

          • Is this an admission that the Hollywood version of stopping power, and the one where momentum is relevant, are one and the same?

            If it is not, could you prove for me why not?

          • AlDeLarge

            Are you really this stupid?

            It’s relevant to both. Do you believe everything is all or nothing, only one or the other?

          • Perhaps you could prove this assertion. However, judging by your posting history, I suspect you are more interested in petty insults.

            Which is cool, you know, everyone needs a hobby.

          • AlDeLarge

            I don’t have much patience for people who spend more effort trying not to understand something than it takes to understand it. I’ve already tried to explain how what you shown here proves it, but you are impervious to reason.

            I’ve been meaning to ask about “area under the curve of the sum-of-drag function.” Why, how, and what is a sum-of-drag function, and why and how are you going to integrate it?

          • Apparently you do not, as you wasted no time at all in insulting me. Interesting, though, that I am the one impervious to reason. I’m not sure how you’d know, since you seem to have chosen to pick a fight rather than engage in discourse.

            Ah yes, clever. Find the one grammatical error in all of my comments here, caused by typing on an aging smartphone, and parade it around as evidence of mental shortcoming.

            You’ve come in here, insulted me, refused to explain your position, bandied about your own poor ability to convey ideas as some problem with my mental faculties, called me a troll (!), and now you’re going to attack the single grammatical error I made in 26 comments. Aren’t you just a one-man band?

          • AlDeLarge

            Yes, I often fail at explaining things to people who refuse to understand simple concepts like the fact that “relevant” and “only” are different words.

            I really don’t care about your grammatical errors; I’m asking about the ridiculous math. If you weren’t talking about integrating a summing function, what were you talking about?

          • I thought it was fairly clear from context that I was talking about the total drag experienced by the projectile during its travel, grammatical mistake or no. That would be the area under the drag curve, or a “sum” of the drag in an arithmetic sense, not a calculus one.

            Pretty easy to understand if you’re not reading it starting from the premise that I must be some kind of room-temperature vegetable.

          • BobDole_is_my_waifu

            You’re a faggot, please leave and never come back

          • Now, language like that does not belong on this site.

          • AlDeLarge

            Trying to prove you’re as smart as Nathaniel?

          • BobDole_is_my_waifu

            I’m just trying to prove that you are highly misinformed and not providing evidence to support your argument.

          • AlDeLarge

            Oh yes, I see now. Your comment certainly was eloquent and insightful, full of poignant counter-arguments.

          • CC

            From the perspective of a casual observer you are doing very poorly in this argument.

          • Zebra Dun

            The weight of the fired bullet is the same after being fired with the momentum.
            The recoil is dampened by the weight and mass of the rifle.
            Which slows the forces down over a span of time.
            If a rifle was the weight and size of the bullet, when fired should hit your shoulder as hard and as bad as the bullet hits the target.
            ” I think, not being a physicist”

          • This is correct. You’ll also note that if the rifle were that light, it would have the same (actually somewhat greater) energy as the projectile.

            Energy is a much better predictor of terminal performance than momentum.

    • n0truscotsman

      I believe the worst part is when people believe that 50-100 ft lbs of energy is somehow a “measurable” difference in energies between different types of cartridges.

      • I’ve seen this over and over again. I think some people want a “magic” number, and if a round/rifle combination doesn’t hit that point exactly, then they’re not titillated enough. Never mind that these numbers pretty much exist entirely in their heads.

  • David Knuth

    Energy and temporary cavity is rarely as important as permanent cavity and damage done to soft tissues.

    With rifle rounds, energy increases in performance as they are capable of generating enough disruption and, for want of a better term, stretch to the tissue that it is driven beyond its natural elastic limit and tears/incurs damage simply by the violence of the disruption through the temporary cavity’s creation. (I tend to use the word “Cavitation”, however I’ve been told it’s the wrong word for this context. We all know, however, what a temporary cavity is, and the general idea behind its creation by the bullet).

    The more violent the disruption, also, the more chance that it may cause damage to more remote structures outside the path of the bullet than caused by the bullet’s path itself. However, in my opinion, it should be noted that the primary wounding factor remains the bullet itself, thus an expanding, tumbling, or fragmenting projectile is superior to ball ammo in this regard as it will cause more permanent damage that is likely to continue to bleed more profusely once tissue has relaxed following the temporary disruption.

    With handgun rounds, as no handgun rounds (short of, arguably, the custom really-hi-velocity loads in the 5.7mm, and then I haven’t seen enough data on their use in a pistol to be more than anecdotal) generate sufficient velocity or energy even on the high end to cause disruption capable of doing the type of ancillary damage to tissue that the rifle’s pressure wave will (with the possible exception to damage done to structures such as kidneys which are relatively inelastic organs and are much more sensitive to shock), energy is far less a component to wounding effectiveness as is penetration and wound channel diameter, both largely eclipsed by shot placement.

    This is why in Handguns, the three major components for loads to consider come to penetration, expansion, and controllability. In this case, physical characteristics are the highlights, and energy is purely a byproduct.

    With a properly effective handgun round, the FIRST consideration is getting the bullet on target. With the fact that a handgun is much harder to keep on target than a rifle simply due to limited points of contact and limited surface area for bearing and mitigating recoil, you’ll need to ensure that this is a primary concept. Ensuring proper placement in the body ensures that each round, regardless of your caliber of choice, is able to do maximum damage to the body’s critical organs (Heart, Lungs, Spine, Arteries). The round need only be large enough and have enough energy to penetrate the breastbone to do its thing, though having the ability to penetrate the breastbone and maintain enough velocity to reach the spinal cord or back, completely traversing the torso’s organ cavity is far preferable. (I’m looking at you, .25ACP and .32).

    Once you get past the bone and into the body’s cavity, improving bullet speed and size nets you more penetration, and begins opening up room for a bullet that is not a solid, unchanging ball but instead can be a hollowpoint that expands to various sizes because there is sufficient velocity and energy to allow the bullet to overcome the greater resistance offered by a larger surface area and still maintain deep penetration.

    Velocity and Penetration also net us a couple of other benefits:

    1. It increases the range at which the round will be effective against a target. Where small guns like a .380 or similar will have to be used in fairly close quarters to maximize performance, a 9mm +P or hotter can be used effectively at much greater distances.

    2. It increases our ability to overcome barriers and adverse angles of engagement. In shooting scenarios observed by police and self defense, a clear shot to the chest square on is rarely presented. Often times the subject’s arms will offer an impediment, clothing or some object will provide an impediment, or you are firing from a position leaving you firing at an obtuse angle on the target, necessitating much more penetration to reach vitals than a square-on shot. This consideration is historically the FBI’s explanation for the 12″ minimum penetration requirement in testing, and it has been observed in several cases where ammo that fails to perform adequately to the FBI’s standards in lab testing have observed failures to reach vitals or follow a straight trajectory due to these factors.

    Anyway, tl;dr: Rifle rounds, use rounds that have enough energy to get you to target with plenty to spare, and a round that’ll do good damage. Beyond that, in rifles anyway, you’re pretty much good to go as long as you keep range of effectiveness in mind.

    Handguns, stop worrying about energy, start worrying about accurate shots to the right spot, fast follow-up shots, and reliable function. Everything else is ancillary and academic and worth considering only once you’ve been able to beat Jerry Miculek (who I’m sure I misspelled the name of) et al on fast, repetitive shots.

    • Jeff Smith

      ^ Yea, what he said.

    • Kivaari

      Very well stated.

    • n0truscotsman

      Im impressed by that comment. Well done.

      I see so many gun owners get wrapped around the axle when it pertains to handguns. To me, I never argue that hard for handguns, since I am a follower of old school infantry frame of thought, handguns are merely side arms or a means to carry concealed, nothing more. If I have to fight with one, something went seriously wrong.

      and I am just a guilty, having gone through 357, 44, 10mm, and other magnum phases myself and worshipping the “if it doesn’t start with .40…” altar. Then I discovered the importance of a good, functional long gun.

    • iksnilol

      What about using a sabot in 7.62×25 (.224 Boz ?). Would that be fast enough (about 670 m/s with a 50 grain bullet)to cause tears and whatnot?

      Also, well written. As long as it penetrates and you can control it, everything is dandy (also 32 is better than 380, just to start a caliber war).

      • Blake

        mkay, I’ll bite, Mr. “32 is better than 380”

        if it’s .327 fed mag maybe, or 32 NAA

        • iksnilol

          Not bad but I was thinking .32 ACP simply because it penetrates about 20-30% more than .380. My favorite is the CZ 83 in .32 (15 rounds in a compact package).

          Also what Dugan Ashley said: “7-6-2’s on the spot, sure to make the mother f#*king bodies drop. Maazine is so clean, feeds straight to the top
          Killing like cholera, nothing but head shots.”

          Granted that was about AKs but 7.62 is 7.62.

          • valorius

            Buffalo bore .380 “+p” hcfn lead penetrates over 32″ of gel.

            There is no world where .32 acp is better than .380 acp.

          • Blake

            We’ve got a CZ 83, but it’s chambered in .380 &ltgrin&gt

    • Blake

      Excellent comment David.
      I’d mod you up twice if I could 🙂

    • valorius

      From the five seven pistol, the fastest rounds as loaded by elite ammo co, will hit approx 2400 fps. Most of The rounds you can get that are loaded to this velocity level tumble on impact. Some, such as elite s4m will also show a jacket fragmentation efffect, and penetrate between 12-14″ in gel. Pretty hard to imagine that round not beong highly effective. It will also defeat a high quality top end IIIA vest easily. In fact in the gel tests ive seen, the damage the round does to gel is greatly increased if it has to penetrate body armor first.

      Brassfetcher has lots of 5.7mm gel tests on his site, and a user on youtube named buffman has tested pretty much every available 5.7mm load against numerous types of body armor.

      Energy is not that important in most cases, but geo tests alone can be very deceiving, as a bullet needs the ability to also penetrate heavy bone. A gel test that shows this clearly is on on you tube that compares the terminal effect of .380 hormady critical defense to .380+p buffalo barnes against gel encased bones. The hornady round is literally stopped in less than 1″…. Whereas the buffalo barnes round shatters the heavy bone and still penetrates about 5.5″ before stopping.

      In gel alone they have similar performance….but add bones to the mix, and the buffalo barnes round is vastly superior.

      • David Knuth

        I admit that I don’t know much about the 5.7mm or its effectiveness. Data from Law Enforcement using factory ammo has not been promising, but then, factory ammo is not loaded to the spec that Elite Ammo is.

        As a boutique round, I think it works based on the numbers, but…I’d rather stick with common loads.

        • valorius

          I dont know that id call a round that was very close to being adopted nato wide and that is in use with both the usss and the queens personal body guards a boutique round, but it is admittedly still not quite mainstream.

          Brassfetcher has stated that fn ss195 (2000fps from pistol) and ss198 le only (2100fps from pistol) tumbling rounds are comparable in terminal effect to .45 acp 230 gr jhps. Elite s4m uses the same bullet, but driven to 2400fps.

          Common legacy loads are ok though, until you face someone wearing body armor.

          To me the real advantage of 5.7mm besides the very light recoil is the compact size and light weight of the ammo. A standard 5.56mm ammo box holds 1200rds of 5.7mm.

          It has its advantages.

          • Shawn Thompson

            the 5.7 was abandoned a while ago by the US SS after studying many failures to stop and poor performance. that is old news

          • valorius

            No it wasnt, the round has proven highly successful in actual shootings.

            Thats urban legend.

      • Zebra Dun

        How does the 5.7 mm compare to the old Tokarev/PPSH 7.62 x 25 mm round?

        • valorius

          For most loads Both have similar armor penetration and energy levels, but 5.7mm has a tumbling effect that 7.62 tok doesnt. Factory tok flatnose ammo behaves like a flat nose handgun hunting bullet.

          Fn ss190 steel core and elite t6 both have armor penetration far beyond milspec tok. Those rounds will penetrate well in excess of 100 layers of kevlar.

  • brianfromohioviatexas

    I don’t like terrible soundtracks laid over hog hunt videos.

    • TheFirearmBlog retains no responsibility for the awful soundtracks of any hog hunt videos. 😉

      • iksnilol

        I wonder why they don’t just blast “Ride of the Valkyries” or “Long Tall Sally” out of the choppers. It’s not like the hogs will hear the music before them.

  • derfelcadarn

    I do not care how little or how much energy a round generates, the serious question is can you shoot it ? Can you hit the target every time, a well placed shot does more towards than any amount of energy. Admittedly there are exceptions, rhino no matter how well shot with that .22 cal. short are going to present some thrilling moments, but nonetheless well shot is better than shot hard.

  • STW

    I was taught this lesson early on. Forty to fifty years ago I read Robert Ruark’s “Uhuru.” The hero(?) of the book while scouting for anti-Mau mau forces shoots an insurgent. Upon examing the body he realizes he’s using too much gun and needs to send back home for something more practical and cheaper to shoot (since he was furnishing his own ammo). I may even have still been in grade school when I read that.

  • n0truscotsman

    There is always a tradeoff when you get higher quantities of energy: recoil, expense, gun size, etc. Those peculiarities may cross the line between a usable to unusable firearm for an individual.

  • BattleshipGrey

    I was pretty impressed with the 6.5 Grendel. I always read it’s praise on forums from the Grendel fanboys but I just figured why bother it’ll never catch on so I never really looked into it. I still won’t diversify into another caliber for a long time though. 13 is way too much to keep up with as it is. Long story short, I was impressed with what I saw.

    • The 6.5×38 definitely emphasizes energy retention uber alles; in my opinion this hurts it in other more important areas, like trajectory.

      Further, it’s very annoying to me that Alexander Arms and others continue to push performance figures for that round that are simply incorrect for a normal production load.

      • iksnilol

        How does energy retention hurt trajectory? I’m kinda new to the whole ballistics game.

        Also can you just neck down x39 brass to 6.5 and have a pseudo Grendel?

        • engr

          In a nutshell:

          * Improved velocity = decreased time of flight = improved trajectory
          * Improved velocity = increased drag = decreased energy retention

          It’s all tradeoffs, all the time.

          • While projectiles moving at higher velocity do experience more drag, they also cover distance during the time when they’re losing velocity. Because of this, a projectile of a given type fired at a higher velocity than another projectile of the same type will retain energy better.

          • engr

            Being pedantic here:

            A projectile of a given type fired at a higher velocity does not retain velocity better than an identical projectile fired at a lower velocity. At any given distance past the muzzle, the higher velocity projectile will have retained less velocity as a percentage of initial starting velocity than the lower velocity projectile due to increased drag.

            The higher velocity projectile will still maintain a velocity advantage at every given point past the muzzle (until impact), but that’s a function of higher initial velocity despite worse velocity retention.

            The energy retention vs trajectory tradeoff is only applicable if you keep projectile energy level constant. Dumping more power into any given projectile will obviously improve trajectory and energy levels at every given point past the muzzle. At that point, the tradeoffs move to a different arena (recoil, ammunition weight, platform weight, etc).

          • Yes, you’re absolutely correct here; as a percentage of their starting energy, they retain less of it, due to there being more area under the curve of the sum-of-drag function.

        • The 6.5×38 loads very long, heavy bullets at fairly sedate velocity. Below about 700m, velocity is the primary factor in trajectory. Because of its relatively low velocity, even despite its high BC bullets, it has a fairly rainbow-shaped trajectory. Given a maximum effective range of 5.56 as fired from the M4 of 500m, under the same conditions the 7.62×39 has a maximum effective range of 400m. If you follow the link, you’ll see that PEO Soldier Office considers this 100m range overmatch for the M4 versus the AKM to be very important. The 6.5 Grendel, by comparison, has a 450m MER, by the same standards. So, it halves the range overmatch of the M4 platform versus AKM-armed opponents.

          How much does this matter? I can’t say, but low-velocity projectiles, even ones with good bullet shape and energy retention, tend to have very poor trajectories as relevant to individual small arms.

        • Blake

          “Can you just neck down x39 brass to 6.5 and have a pseudo-Grendel?”

          If you can get PT&G to make you a reamer for “pseudo-Grendel” then go for it…

      • Blake

        I like the concept of 6.5 grendel. I think one thing holding back wider adoption is the continued unavailability of the announced cheap Russian ammo like Barnaul (& the current sanctions situation isn’t going to help anything).

        However I do agree that the politics behind its development are pretty rough & unfortunate, and that the lack of initial velocity means that the round only stands out over others available for the AR platform at extreme ranges well beyond those for which the weapon was designed to be used.

        Given the development target of the AR platform, I think a better performing & more practical round could have been developed using the same Lapua 7.62×39 parent case but using a 90gr .22 cal match bullet (which is too long to fit in a standard AR magazine when loaded in a .223 case) & a 1/7 twist bbl.

        These bullets have virtually identical G1/G7 BCs to the 130gr 6.5mm bullet used in the Grendel but are 30% lighter so they’ll launch significantly faster, & has the advantage of being the same caliber as plain old 5.56×45 so the same cleaning kits, flash hiders, etc can be used.

        • I admit, I don’t really see the merit of a round that’s heavier and has a worse trajectory than 5.56mm, especially one that takes so poorly to leadless and tracer projectiles.

          It does seem well-suited to hunting, though, which makes sense, as I seem to recall reading somewhere that was its original intended purpose.

  • Blake

    These should help folks understand sectional density & why it’s important:

    http://www.chuckhawks.com/sd_beginners.htm
    http://www.chuckhawks.com/sd.htm

  • CHOMP

    Thank you for an interesting article. I think it would be interesting to see the difference in wounding profiles with the same high sectional density projectile (ie 300 blk 240 smk) in a supersonic and also a subsonic test (10% VYSE ballistic gel)or equivalent . Then also a test with same said projectile just a larger meplat (like a WFN lead bullet) shot super and subsonic. Shit maybe I should do it, and stop posting such silly madness here. None the less I do enjoy your blog.
    Thanks, CHOMP

    PS. I can’t forget the UNSC36000 projectiles also.

  • iksnilol

    I thought that the 300 BLK is better since you can shoot it farther? At close ranges there isn’t much difference between .45 ACP and 300 BLK, but have you tried shooting .45 at 200-300 meters distance?

    I digress, I still use the 7.62×39. Out of a 30 cm barrel it works well.

    • If you compare the subsonic loads of .300 Blackout with subsonic .45 ACP and 9mm using a ballistic calculator like that on JBM Ballistics website, you’ll find that their effective range isn’t that different. Trajectory, especially at short range, is mostly dependent on velocity, not ballistic coefficient.

      • iksnilol

        Dayum! Didn’t expect that.

        At least the high BC bullets are better at resisting wind…are they?

        • Blake

          sure, but if you’re engaging targets with subsonic loads at ranges far enough for it it matter much then wind is probably the least of your worries…

  • Mark Kraemer

    Well done. Probably the best post I’ve seen on TFB in recent months. Kudos too for the comments. I’ve seen one very well thought out responses.

  • zeprin

    Sorry but Accuracy trumps all other considerations.
    Quite simply, You Can’t Kill It If You Don’t Hit It.
    Closely followed by Penetration.
    In my personal list of Bullet performance must haves, Upset/expansion/energy dump comes in at about #7 on a list of 2.

  • Zebra Dun

    I want a round I can put on target with fast follow up accurate shots that penetrate for self defense.
    Expansion, tumbling and exploding doesn’t matter.
    I plan on placing a bullet that will drill through at any angle, side to side, bone or right up the middle if the target is prone without stopping.
    The round can stop after it leaves the target but it must go through.
    I use FMJ in a .45 ACP, Silver tips in a .45 L colt and Hydra shocks in .38/.357
    I use silvertips in 30/30 and FMJ in the 5.56 x 45 mm.
    I don’t plan on shooting nothing human but I believe in being prepared.