The Misconceptions Surrounding Terminal Performance of Bullets
Separating fact from fiction in the science of bullet terminal performance
By Aaron Peterson — Founder, Hawkeye Ammosmithing
“Data-driven ballistics, tested & proven.”
© 2022 Aaron Peterson. All Rights Reserved.
U.S. Copyright Registration No. TXu002301231
Disclaimer: The following is not a discussion on my personal opinions and preferences for or against certain bullets. It’s strictly a guide and about discussing misconceptions and misunderstandings about perceived terminal performance of certain bullets and how and why I believe certain conclusions are made. I do stand by everything written here, but I also fully understand and appreciate that people have their own preferences and rules of thumb. If it’s worked for you without failure, by all means do what’s right for you. It should also be mentioned that this is written with the North American hunter in mind, particular the American hunter, and those animals typically hunted in that region of the world. African game, for example, would likely require other considerations not discussed here.
Topics Covered
- Marketing, Word of Mouth, and Tradition
- Bullet Construction and Perceived Terminal Performance, Part 1
- Bullet “Failure”
- Meat Loss/Damage
- Energy
- Bullet Construction and Perceived Terminal Performance, Part 2
- Stability, RPM, and Centrifugal Forces
- My Rules of Thumb Regarding Impact Velocities and Sectional Density
- Bullet Pass-through Versus Non-pass-through
1- Marketing, Word of Mouth, and Tradition
I was chatting with a fellow hunter recently, and discussing the terminal performance of soft/frangible bullets like the Sierra SMK, GK, TMK, Hornady ELDM, A-tips, Berger Hybrids, etc and how they compared to your more “traditional” hunting bullets. There are a lot of misconceptions out there regarding the results many hunters see and perceive, one way or another, after taking a shot and examining the results on the animal. A lot of the misconceptions, in my humble opinion, can be blamed on misleading marketing as well as uninformed marketing, from the bullet manufactures themselves. Hunters need to realize that making a profit is the number one priority of any business like that, and marketing is a huge part of making sales. They’re typically going to make a product sound as good as they can, to include making claims not easily proven one way or the other. It’s easy to get caught up in the marketing. After all, you want to be able to trust the manufacturer, right? They’re making the product, testing it, and many have been in the business a long time, so you want to believe you can trust them. I get it, and I agree. That said, just because their intent may be pure, it doesn’t mean what they’ve created and determined, and thus marketed, is actually true and works as advertised.
Conversely, just because a bullet manufacturer doesn’t advertise or recommend a certain bullet of theirs for hunting, it doesn’t necessarily mean it shouldn’t or couldn’t be used for hunting or that it will result in poor performance. There are underlying reasons certain bullets won’t get the nod for hunting and a couple big reason are one, politics and defense contracts that the particular manufacturer holds, and two, when a particular bullet wasn’t specifically designed and made for hunting and thus has not been properly tested by them for that purpose. Most manufacturers aren’t going to advertise/recommend a product for something they haven’t tested themselves. Bullets used in defense contracts can’t be advertised to be “expanding” due to NATO and Geneva Convention rules, primarily due to the 1899 Hague Declaration. If bullet manufacturers advertised the bullets they use for their defense contracts as expanding, they’d risk losing those contracts. So, between that and the similar European regulations and the fact that they import/export and sell their bullets worldwide, they have to do what they have to do. This also includes bullets that share the same nomenclature as others used in defense contracts. Luckily for us, all you need to do is a little research on terminal ballistics to understand how a particular bullet will likely perform based on its construction/composition, and apply that to your hunting needs. Occasionally some further testing still needs to be done before you can just go tell the world a particular bullet will do exactly what anyone would want. You can also do your own research and find things like Hornady’s LEO website and discover that they actually do speak highly of their AMAX and ELDM line of bullets and how well they expand and perform terminally used in that application.
So besides marketing, a lot of misconception simply gets passed down from family and friends, via word of mouth. We tend to look up to those people and trust them, assuming they know what they’re talking about. Don’t get me wrong some certainly do. Either way, once you get it in your head that a certain type of bullet is what’s necessary, and truly believe it, it can be very hard to change your mind. Many hunters tend to become quite stubborn and are extremely reluctant to change their views or admit to themselves they may be wrong, let alone to others.
It should perhaps be mentioned upfront that there is always a measure of luck that’s involved in hunting- whether simply the luck of animals actually presenting themselves for a shot, or by getting a good shot off that just so happens to impact within the particular bullet’s limitations that you’re using. The latter actually happens a lot, and can definitely produce a sense of false confidence with a particular bullet or class of bullet. Folks also tend to conclude that the result on the animals from those bullets is what you should always strive for. The commonly passed down standard for “proper results” goes way back to muskets, and before. Projectile technology and performance was obviously very lacking back then. You pretty much always anticipated a track job. The projectiles also didn’t really expand and the size of the projectile was very large because that’s what was needed then in order to produce wide wounding. Back then it was all about the wider the bullet, the faster the kill. As rifles progressed, and we started getting into actual cartridges utilizing black powder, projectiles improved, but calibers were still typically in the .45-.50 size range and were still chunks of lead. Terminal performance was overall about the same as before. This has led to multiple generations having the idea of two holes (entry and exit wounds) is the ideal terminal performance so that you can get ample blood spilled in order to track the animal, which was almost always required.
Well, fast-forward to today, and we have made huge advancements from those days. We now have smokeless powders, faster velocities (supersonic), the need for copper jackets to reduce the lead fouling you’d otherwise experience from pushing a solid lead projectile to supersonic speeds, and then the reduction of caliber size required for proper terminal performance. The reduction in caliber size has also produced an increase in bullet efficiency and increased ballistic coefficient (BC). The cartridges themselves have also advanced and have increased in efficiency as well. Target shooting and recreational shooting sports and competitions have developed and boomed, ever-increasing in popularity. Bullets continue to advance to keep up with this demand. Jacket thicknesses, along with lead cores and alloy content, have evolved as well. Even producing projectiles made entirely of copper or brass has now become a HUGE market. Things have changed so rapidly that there simply hasn’t been enough time for the industry to keep up with understanding these changes and how it’s affected terminal performance for hunting and what truly works the best nowadays. Those many decades of desiring large exit wounds and big tough bullets have managed to carry on. Hunters are also a proud people and tend to stick to tradition and hold on to the ways of past generations. They also tend to resist change and to keep an open mind to a different way of looking at things. Like I mentioned earlier, they tend to be quite stubborn in their ways.
This finally leads me to the main point of all this: Trying to convey a better way; to help folks better understand terminal ballistics and bullet construction/composition; to understand bullet limitations and how to select the right bullet and the right weight of a particular class of bullet for their particular hunt, and to discuss and dispel common myths and misconceptions. Let’s continue the discussion below:
2- Bullet Construction and Perceived Terminal Performance, Part 1
I’ll start now by giving an example scenario: let’s say a skeptical hunter that has never used anything but specifically marketed “hunting” bullets has been on the internet looking at others’ experiences hunting and has seen many folks talk about their successes using match style “target” bullets on their hunts. After much consideration he finally decides to give them a go himself and buys a box or two of Hornady ELDMs or Sierra TMKs, works up a good load, and is ready to go out on a hunt. He has this beautiful buck come walking out at 280 yards. It’s quartering-to him, yet he aims in his usual spot (just behind the shoulder). He takes the shot; the buck leaps, then makes an attempt at running, manages to get about 5 or 10 yards, and then piles up. Upon getting to the animal, he discovers there’s no exit wound and little to no blood coming from the entry hole either. This has already raised a flag for him, as he has been raised to desire an exit in order to create a blood trail if tracking is required, which in his previous hunts it typically always has been. So now he’s already thinking this bullet hasn’t really performed as he’d hoped or thought it should. Next, he begins to field dress the buck, and during the process he has discovered the bullet did a good number on the rear lobe of the left lung. He then sees multiple lacerations on the liver, and then sees bits of rumen and evidence the bullet traveled into the guts. It’s looking like a real mess in there. He’s now even more convinced this bullet didn’t perform well. He’s found bits of jacket and bits of lead here and there in the cavity and surrounding tissues as well, making the conclusion that the bullet completely came apart and “failed” as a result. He’s just made up his mind and the conclusion that he was right in his previous bullet choices and has decided that these bullets have no place in hunting as they just “blow up” and don’t even produce an exit wound so you can properly track it. I know there are many hunters out there that agree with this and have maybe experienced something very similar.
Let’s stop and take a closer look at that example. Let’s clear our minds and any bias based on what you might have been previously taught. In that particular scenario, a tougher constructed “hunting” bullet, such as the highly popular Remington Core Lokts, Nosler Accubonds or Partitions, Hornady ELDX or SST, etc, etc, and even many of the popular copper variety hunting bullets might have actually performed much worse with that particular shot. They most likely wouldn’t have come apart quite as much and while the animal would have likely still died at some point, it also most likely would have been a much slower death and very likely would have ran a long ways before succumbing to the wounds and/or asphyxiation. Yes, an exit would have, or could have, definitely proved useful in a situation like that. It’s very possible any of those bullets would have simply gone through the lung and punched out between the liver, and in that scenario, a lot of times death doesn’t occur for a long time.
Bullets such as Sierra SMKs, GKs, and TMKs, Hornady ELDMs or A-Tips, Bergers of the hybrid ogive design, etc are actually very forgiving to less than ideal shot placements like in that example scenario because they do indeed come apart and they’ll inflict much more damage, create much wider wounding, transfer more energy, and cause a much faster death. The softer/frangible bullets still tend to shed enough material outwards that they’ll still hit liver and/or lung when shot placements aren’t ideal and are in that “no man’s land”, and will typically still cause enough blood loss to find and recover the animal not far from where it was shot.
What a lot of people see when using bullets like the SMKs, GKs, TMKs, ELDMs, Bergers, etc is what looks like the bullet came apart and didn’t exit, and to them it seems like poor performance, but what they fail to realize and comprehend is what’s right in front of them. They actually DO have the animal, typically very near where it was shot, and they’re actually able to cut it open to see those results, rather than still being out there trying to find the animal, or finding it a very great distance from where it was shot.
3- Bullet “Failure”
Classifying bullet failure tends to be quite subjective. Many hunters believe that if a bullet did not perform in the manner it was designed and advertised to, it failed. That’s not completely true though, and not fair to the bullet or the manufacturer when the hunter, even unknowingly, used the particular bullet outside its limitations. You cannot expect a bullet to perform perfectly when/if you used it beyond its capability, even if it is advertised to expand or not to over-expand. They all have their own limitations. If a particular bullet impacts below its limitation for impact velocity, you cannot expect it to still adequately expand. If it doesn’t meet sufficient impact resistance, you cannot expect it to expand either. Conversely, if a particular bullet impacts above its velocity limitation you cannot expect it to hold together well, or if it encounters too much resistance upon impact, especially if it has insufficient sectional density for such a shot. These things should not be reason to conclude a bullet failed. It wasn’t the bullet’s fault, it was the hunter’s fault for not understanding the limitations of the bullet and/or not adjusting shot placement as required.
When a bullet actually fails, you typically don’t have an animal to examine. A true failure would be when a bullet is used well within its limits, placed properly, yet death did not occur, or at least not quickly. It might be because the bullet didn’t perform properly, even though it was within its limits, but if you don’t have an animal to examine, or the bullet, you cannot know for sure. The animals that get hit with shots like in my example scenario, and with bullets like Core Lokts, etc, and the animal simply takes off never to be found, is when most people think they simply missed. In reality, most times they do hit the animal, but the bullet did not transfer enough energy to drop it, nor create sufficient blood loss in a timely matter to cause a quick enough death to even see the animal ever drop. This too isn’t what I’d consider a failure of the bullet, but a failure of the hunter using and/or placing that bullet outside its limits or in a poor location on the animal.
All of this is essentially an example of what’s called “survivorship bias”, but in reverse. If you’re unaware of this term, a good example comes from WWII when a statistical research group was working with the US military to figure out how to increase the survivability rate of bombers during missions. The military was only looking at the bombers that returned and taking note of the areas of the planes that got shot up and concluded those areas needed strengthened and armored, whereas the statistical research group, led by Abraham Wald, determined that those planes made it back because they were only damaged in those areas, and that the areas of the planes not shot up were actually the areas that needed armored because those were the areas that if actually damaged would not allow the plane to survive and those were the areas destroyed on the bombers that did not return.
In WWI, the British thought their new helmet was actually causing more brain injuries because the hospitals had a huge increase in admissions after the helmet started being used. In reality, the soldiers were surviving and being treated rather than simply dying and never even making it to the hospital.
So, as it relates to hunting and bullets, people tend to only look at the animals recovered and create a bias on the perceived results based solely on those instances. They don’t factor in the animals that got away because they figure they either missed or they simply never find and recover the animal or bullet to see the results to even know what really happened inside the animal and with that particular bullet. Like in my example, they see a bullet that came apart and want to assume that it’s poor performance, even if the animal dropped on the spot or only went a few feet or yards. They tend to focus on things they’ve heard or have been told and only focus on the small picture rather than the big picture and what’s right in front of them.
Many people want to conclude that a bullet that didn’t exit failed. Honestly, if it truly failed, you wouldn’t have the animal to even see that it didn’t exit. More times than not, the true failures are the times the animal was never recovered because the bullet simply didn’t inflict sufficient trauma to cause a quick enough death, or death at all. Bullets that create exits that allow for a blood trail, and a blood trail that’s actually needed to track it, are also to be considered not ideal performance since needing to track it via a blood trail is a sign that death did not occur as fast as it could or should have. That said no bullet is going to work 100% of the time, every time. There are always going to be anomalies with both the bullet, and the particular animal. Some animals are dead on their feet and can defy all odds and logic and still manage to run without having any of its vital organs still intact. It’s truly remarkable sometimes. These situations shouldn’t be cause for rejection either. You shouldn’t write-off a particular bullet or class of bullets based on one poor result, or perhaps even a few poor results if there’s a reason for the poor performance other than simply just the type of bullet being used.
4- Meat Loss/Damage
Moving on a bit, another common misconception and misunderstood subject involves meat loss/damage and meat saving shots. First off, there are a lot of hunters out there that simply don’t know how to properly determine when meat is actually damaged and inedible. They see areas that are bloodshot or areas with pooling blood and determine that entire section of meat is damaged and inedible. The fact is blood does tend to pool in areas and make it look bad, but it’s usually fine when taken care of properly. Pooling blood and bloodshot areas can mostly be rinsed away and any areas that are in fact damaged and inedible can simply be trimmed away. The amount of inedible meat trimmed away usually comes down to less than a pound, when placing your shots appropriately and using the bullet within its limits.
The amount of meat damage with certain shots will always depend on bullet construction/composition, impact velocity and the amount of resistance the bullet encounters upon impact, plus things like the angle of the shot, and muscle tension and density upon impact. A relaxed shoulder will typically result in a different amount of wounding versus a contracted shoulder. Even the bullet’s RPM has a big influence on wound channel size as well, in regards to centrifugal forces causing the bullet to come apart more or less. I’ll talk about this more later.
Besides headshots and gut shots, it’s near impossible to get reliable and repeatable results- killing quickly and humanely (not talking ethics here)- without losing at least some meat. It’s just the nature of the beast. Proper bullet selection is crucial. By placing your shot accordingly, based on that particular bullet and the impact velocity it’ll be at when it hits the animal and at the distance you engaged it, you can balance out the amount of expansion and penetration and achieve best results with minimal meat damage yet still produce a quick death. Hunters that desire a quick and clean kill with zero meat loss in a repeatable, consistent, and reliable manner are living in a fantasy world. Sure, you can get lucky, but getting lucky is not a repeatable, consistent, and reliable thing.
Blood loss is what kills most efficiently, reliably, and quickly. Hitting an animal in the body and inflicting enough blood loss to kill the animal quickly, but without losing any meat is just not something you can count on. You run more of a risk losing an animal with bullet performance like that than you do dropping them and killing them quickly. And honestly, if you use the right bullet, within the limits of that bullet, you’re really not going to lose a lot of meat with even a shoulder shot. Guys act like shoulder meat is the best meat on the animal and that they’re going to lose so many pounds of meat placing their shot there. That’s simply not true- not unless you used the wrong bullet or placed it in the shoulder when it would be impacting well outside it’s limits, as in too high of an impact velocity and/or amount of resistance for the bullet type and weight you’re using. That’ll result in shallow penetration and over-expansion near the surface. That indeed will result in more meat lost, but that’s not the bullet’s fault or necessarily the shot placement’s fault either. It’s the hunter’s/shooter’s fault for not knowing that would be a poor shot placement under the circumstances for that particular bullet. That’s when a behind the shoulder shot, or neck shot, or even head shot would actually be a better choice.
Bullets that don’t shed weight and hold together do tend to reduce meat loss/damage, but that comes at a trade-off. Typically, the overall amount of wounding and trauma is less with that type of bullet. If it impacts below its ideal velocity, the amount of wounding and trauma will be even less. If you miss vitals, you may very well miss recovering the animal too. A well constructed cup and core bullet, for example, that will indeed shed weight can be much more forgiving in that particular scenario since it would produce wider wounding and may still reach vitals, producing more overall trauma, and be the difference between recovering the animal or not, just as I mentioned before.
Ultimately, there are multiple factors to consider, but in my experience and all the research and studying I’ve done and with all the other info shared out there from others’ hunts and experiences, I have concluded you simply cannot guarantee consistent, reliable, and repeatable quick and clean kills with zero meat loss. It’s always been more worth it to me to pick the right bullet and place it accordingly and lose a little meat than it is to risk losing ALL the meat by potentially not recovering the animal.
You can’t guarantee a particular presentation of the animal either to count on executing your favorite particular shot placement. You can, however, still place your shot in other ideal areas to give you desired results- that being a quick and clean kill and a recovered animal.
When a hunter starts talking to me about how they want a bullet that penetrates deep, doesn’t damage meat, exits, and gives them a big blood trail to follow, all while producing a quick and clean kill, it immediately tells me they don’t fully understand terminal ballistics and bullet construction/composition, and the anatomy of the animal they’re hunting, along with the basics in effective killing of game animals. You do not NEED a blood trail if you truly know what you’re doing, are using the best bullet for the job, and place it in the appropriate place according to the situation you’re presented with. A lot of people like to use the phrase “if I do my part”. Well, I say that means knowing all of the things I just mentioned. Also, if you actually use the right bullet and can implement the high shoulder shot under your particular circumstances, you won’t need a blood trail to track it.
5- Energy
Disclaimer: Again, if you have a personal preference and/or rule of thumb regarding minimum energy and it’s worked well for you, by all means do what’s best for YOU.
This leads me to yet another misconception often discussed and touted as a crucial factor and something used as a minimum or rule of thumb for a particular load/ammunition they’re using, and that is: Energy. Personally, I stopped even looking at energy several years ago now. It’s just not even a concern of mine if I know the minimum impact velocity limitation of the particular bullet I’m using, and if I’ll be within/above it. Impact velocity, sectional density, and shot placement are the main factors I worry about, and the factors that influence those things. Energy is great and I do want it, don’t get me wrong, but it’s only a potential and the bullet has to transfer that energy for it to really work in your favor. Plus, if you’re operating within sufficient impact velocities, there’s going to be plenty of energy to go a long with it, as they do go hand in hand.
Ultimately, you still need to inflict sufficient blood loss along with transferring any energy. That’s what’s most important. So an extra 100-300fps or 200-400ft-lbs, for example, isn’t really going to matter much. What really should be the focus is impact velocity as a threshold number, not energy. Energy is only a potential, and if the bullet doesn’t expand properly, it won’t dump and transfer all the energy into the animal anyways. How a bullet performs terminally is dependent upon impact VELOCITY, the amount of resistance it encounters upon impact, and of course the construction/composition of the particular bullet used.
The minimum energy figures you see stated, recommended, and even made as rules/laws out there (like needing a minimum of 1000ft-lbs for elk) are not good information/rules/laws and are made by those that don’t fully understand, or don’t understand at all, terminal ballistics, or are trying to compensate for others that don’t. It’s unfortunately given many hunters a false sense of what is important too.
When you see bullet manufacturers, conservation agencies, big names in the industry, etc talk about minimum energy needed, you want to be able to trust them and believe it’s a figure you need to look at, but it’s just not. Like I said, if the bullet doesn’t expand properly, it won’t transfer that energy at the right time, or at all. What ultimately kills is blood loss, septicemia, asphyxiation, destruction to vital organs, and damage to the nervous system. Transferring/dumping a ton of energy is beneficial only to shut down the central nervous system (CNS). That’ll drop the animal, putting it into a temporary coma, allowing it to bleed out where it lies.
Arrows and spears, as an example, kill based on how much wounding and blood loss they can produce and energy does nothing to help with the kill. So this makes me wonder why lawmakers still allow bow hunting and other similar methods if they think energy is so crucial.
Ideally, you do want sufficient energy with your ammo/load for a quick and clean kill, but if you’re not using the right bullet and not placing it in the right area, it won’t matter. You could have 2000ft-lbs of energy in a bullet at the time of impact, but if the bullet punches or pencils right through, all that energy just exits with the bullet and the animal typically gets away. So what did all that energy do for you? Nothing. The bullet still needs to expand well and create adequate hydraulic shock in order to produce sufficient wounding and trauma.
My figures and rules of thumb with certain types of bullets, in regards to ideal impact velocity ranges, come from tons of personal research and experience, not from advertisements and marketing schemes from manufacturers. Once you get a really good grasp on terminal ballistics and bullet construction/composition, and know how certain types of bullets perform terminally, you can look at a particular bullet that you haven’t already used personally and you can already have a really good idea and assumption/estimate of how that bullet will perform based on that prior experience and knowledge (wisdom).
The thing that’s helped the hunters using magnum cartridges (or any cartridge pushing typical high velocities) is the velocity they achieve, and not so much the energy they produce. The impact velocity tends to be more than sufficient at the typical ranges they’re used. Something that needs to be considered though, is that with those fast pushing cartridges if you use a softer constructed bullet below a sectional density around .260, and on larger/tougher game, especially with shot placements where resistance upon impact is high, you can experience shallow penetration and over-expansion.
This sort of thing is what has led to the misconception that using softer constructed bullets is not ideal or that they simply do not work well at all. Once again, this is simply a matter of using a bullet outside its limitations. If you’re going to use a fast pushing cartridge and want to use softer constructed bullets, you really should be using one with a sectional density no lower than .280 and ensure you adjust your shot placement as required if impact velocity will be over around 2400-2600fps. Avoid areas where the amount of resistance upon impact would be high, such as a shoulder, unless impact velocity is not too high or you have well over .280 in sectional density.
6- Bullet Construction and Perceived Terminal Performance, Part 2
Let’s discuss another example hunter. We’ll call him Frank. Frank tells us that he won’t shoot shoulders because he “doesn’t want to damage any meat” but that he still “always hits vitals” when taking a shot, and by that he means shooting just behind the shoulder. There’s nothing really wrong with that shot placement, but there are actually plenty of vitals behind the shoulder, and if the animal is quartering-to, pretty much all the vitals will be through the shoulder and behind it.
Remember, blood loss, asphyxiation, destruction to vital organs, etc is what causes death. The lungs hold the most blood and a double lung shot will allow an animal to bleed out quicker than a heart shot, especially if the heart is still pumping. The biggest sections of the front lobes of the lungs are behind the shoulder of most animals. Asphyxiation will also set it quickly without the lungs too. There’s also an autonomic plexus behind the shoulder- the brachial. Hitting the shoulder with enough hydrostatic shock will shut down the CNS, dropping the animal, and with sufficient hydraulic shock (bullet expansion and wound channel size) the animal will bleed out before it can recover. It’s an ideal shot placement. It’s not ideal, however, if your particular bullet won’t handle the amount of resistance it’ll encounter though. That’ll be dependent upon the construction type, amount of sectional density, and the impact velocity, as previously mentioned.
Frank has seen match style bullets used outside of their limits (unknowingly) and has prematurely concluded they’re no good, or at least no better than hunting bullets. I can get that. It happens a lot, but it definitely doesn’t mean they’re bad bullets, it just means you selected the wrong one and/or placed it in the wrong spot for the specific shot and velocity. We can try explaining this to Frank, but he likely still won’t understand it or agree with it. Some guys simply won’t listen to reason because they’ve already made up their minds based on what they’ve seen or heard from poor sources. Some people tend to be very stubborn like that. He’s seen what he perceives as poor performance, made his own conclusion, and now won’t change his mind even when you can explain to him what actually happened. He’s just like the guy in my original example scenario.
The truth is poor performance happens with “hunting” bullets too, and any other bullet. They all have their own respective limits and if you execute a shot where they’ll impact outside their limitations, the result will not be ideal. It’s really that simple. Impact velocity (based on the distance to the animal, BC of the bullet, and the starting velocity) and the amount of resistance experienced upon impact (based on shot placement and animal size and anatomy), are the two main factors with a particular bullet and how it performs terminally. So depending on how the particular bullet is constructed and how much sectional density it has will determine how it performs based on the impact velocity and impact resistance.
A lot of people still don’t get that though. They just see either “match style bullets” (also referred to as “target bullets”), or “hunting bullets”. They also think that in general, the heavier the bullet, the “harder it hits”. They think the faster it hits, the harder it hits too. They conclude that hitting fast with a match bullet means it’ll blow up because it’s not bonded and it won’t hold up/together. This logic tends to almost always come from guys that have mostly only shot magnum or other fast pushing cartridges when hunting and that only associate with other hunters with the same experience. So when they or someone they know decides to try a match style bullet, they typically don’t select one heavy for caliber (with more sectional density), and they typically place it somewhere where it’ll encounter a lot of resistance, and even though the bullet did what it could, and in the instances where the animal died and they recovered it, they look at the damage done as they field dress it and process it and conclude that it blew up and didn’t work well at all. They see or hear a couple friends or family share similar experiences and their mind is made up.
The truth is, I’ve had and seen/heard plenty of experiences with match style bullets, tougher constructed and/or bonded “hunting” bullets, and copper varieties. They all work very well when used within their respective limitations, but those limitations all vary quite a bit from each type. They’re not all the same. Folks don’t fully understand this though and tend to use them all the same and/or interchangeably, so their results are not going to be the same and they’ll inevitably end up with less than desirable results at times and make uneducated and false conclusions.
7- Bullet Stability, RPM, and Centrifugal Forces
Speed (impact velocity) is absolutely critical with copper bullets. They lack density due to not having a lead core and are longer as a result, which creates the need for a higher stability factor (SG) than the equivalent lead core bullet. I’ve spoken directly to Bryan Litz, founder of Applied Ballistics, about this, as I strive to get the best information to back up my theories and personal experiences, and he has confirmed having a minimum SG of 2.0 is ideal for copper bullets to get the best potential regarding their full BC value, versus the standard minimum SG of 1.5 for a lead core bullet. With solids, it’s a center of gravity versus center of pressure issue due to them being longer and less dense. A higher RPM as a result of a faster twist rate and/or muzzle velocity is required to ensure the center of pressure remains well ahead of the center of gravity while in flight to keep the bullet from nosing over and tumbling. Beyond an SG of 2.0 though, any increase in performance is negligible. I’ve heard claims that getting an SG of 3.0, 4.0, or even higher with bullets like Hammer in particular produces better performance. After discussing this with Bryan, he also concludes that it simply is not true and that a bullet cannot shrink any smaller in flight no matter how much or how fast you spin it. Once you get to peak stability, that’s pretty much it. Also, in regards to the claims that putting your bullet to such a high SG means the bullet will better retain its stability upon impacting an animal and thus allowing it continue on a straight path, versus being at a lower SG and thus losing stability and veering off of a straight path, after impact… well, that’s simply not true either. Once any object impacts something, any level of stability it had is immediately compromised. Its rate of spin will also retard extremely rapidly due to meeting an object at rest that produces an opposite force upon it. Fluid dynamics also supports that any deformation of the bullet after impact will also alter its path and redirect it, as will impacting hard/dense bone and muscle tissues.
This misconception, in my opinion, stems from guys increasing the bullet’s speed, and thus rate of spin on the bullet (which does increase the SG), allowing them to see an increase in terminal performance, which they think must be related to increased stability. In reality, it’s really only the increase in impact velocity that’s helping, or a coincidence by other variables compounding together like shot placement, muscle tissues and if they’re contracted or not, the path of the bullet through muscle, bone, and organs, centrifugal forces, and actual impact velocity and impact resistance. There are simply so many variables in play that it makes it easy to misinterpret one thing as the deciding factor on a particular result. So because of that, you have to remove certain variables from the equation and just look at the science and physics and what each thing would actually mean on its own.
Increasing twist rate and/or velocity will indeed increase the RPM of the bullet, and thus will increase the SG. What you need to consider from that though is that will also mean a higher amount of centrifugal force upon impact. As the bullet does expand, that centrifugal force will transfer to any sort of deformation at the front of the bullet. With most copper bullets, that’ll be in the form of petals. So increasing RPM can help pull those petals outward and increase the expansion. So yes, increasing RPM with copper bullets can definitely help with the amount of wounding, but not in the form of stability AFTER impact. Also, you can increase the impact velocity and RPM to the point it causes those petals to completely remove themselves from the rest of the bullet. By losing those petals so rapidly and evenly, and only leaving the shank behind, it will allow the shank to continue on a straight path and give the illusion that increasing the RPM and SG allowed that to happen. If this happens after the bullet is already in the chest cavity, that’s not so bad. If it happens immediately, that’s not so good. So there’s still a balancing act in that regard too.
So all that said the focus shouldn’t really be tied to stability. It should be tied to RPM and centrifugal force. There’s obviously some confusion with all of this out there though and people don’t understand it. They make their own theories and we see this incorrect assumption that it has to do with stability. Yes, bullet RPM and stability are related, but stability and the terminal behavior of the bullet after impact are not directly related. It only is if the bullet happened to not be stable at all after leaving the muzzle and impacted sideways or backwards or something like that. Also, you can still actually over spin/rev copper bullets. As previously mentioned, you can still rip the front of the bullet apart from excessive centrifugal forces and experience less than ideal performance by losing the petals and leaving only the base/shank to still pencil through and produce minimal hydraulic forces, especially if what shank remains is small and only pencils through without producing any significant fluid and tissue displacement and thus insufficient wounding and trauma for a quick death. They do require more impact velocity than most cup and core bullets, but you still have an upper limit as well.
As a side note, I should mention too that I fully understand and am aware that there are indeed laws and regulations that tie particular hunters’ hands and that they’re forced to use copper bullets or other lead-free bullets. Thankfully, copper bullets can still indeed work well when used properly. I’m not arguing that here at all. I’m trying my best to still help those hunters make the best choices and be fully informed and to still succeed out there. There are definitely plenty of personal opinions and feelings that get tied up in it, and while I do try to give my opinions, I also try not to be completely biased and unhelpful. The marketing scheme on copper hunting bullets is great, as it should be to sell them. The overall performance when used within their limits is pretty good on a lot of them too. If it weren’t, no one would ever buy them or continue buying them. The performance is only good, however, if everything aligns for you properly. As in your firing solution, impact velocity not too low, shot placement in an area that ensures sufficient trauma and blood loss occurs, etc. In ideal conditions and circumstances like that, they will indeed work just fine.
I don’t want people getting the impression I’m saying they’re absolute garbage and to never use them and that if they do work it’s only due to luck. I’m not saying that. I’m simply saying they have more limiting factors than a well-constructed and selected cup and core bullet. A lot of companies out there making solid copper bullets are doing so to try to corner the ever-growing market that it is. They’re trying to find new ways to produce the necessary terminal performance for ideal results, which is good. There’s a big desire and demand out there for them, because there’s this huge misconception that a bullet that retains all its weight and passes through is most desirable (it’s not though).
In MANY industries, not just in the hunting/shooting industry, manufacturers will produce and offer what the demand is, and not necessarily what should be made and put out there. It’s a “the customer is always right”, sort of mentality. They know they’ll sell because that’s what’s being demanded. Plus, there’s also a big market for them due to states that have banned the use of lead bullets for hunting. Some manufacturers, fortunately, are still at least trying to increase terminal performance as they go. A competitive market and numerous options are obviously a benefit to the consumer. It also provokes innovation.
Also, to be fair, there are obviously limiting factors with cup and core bullets and some hunters definitely mess that up from time to time too. You still need to select the proper bullet construction with cup and core bullets for your specific application too in order to have ideal results. There simply are no magic bullets out there.
Another side note: There always seems to be some sort of controversy surrounding these things too. As much as everyone doesn’t want to believe that bullet manufacturers aren’t always experts and that they don’t all know exactly what they’re doing, they just simply don’t all, unfortunately. Sadly, some bullet manufacturers aren’t exactly operated by the most upstanding of individuals either, which is very unfortunate. So then other feelings get brought into the decision on selecting a particular bullet and even if they’re making a decent product, the people that own the company or work for them might not actually be decent and that may make you less likely to support them as a result.
8- My Rules of Thumb Regarding Impact Velocities and Sectional Density
Something I do want to add to all of this, as I think it could prove useful and is pertinent, are some of my own rules of thumb regarding where I put TYPICAL limitations for the three basic bullet types. I’m always reluctant to discuss this though since it’s not an absolute at all and there are many factors that go into how a bullet actually performs and behaves once it impacts an animal. Please keep this in mind. The amount of sectional density the bullet has or doesn’t have really affects these numbers and ranges as well.
•Impact velocity range for tough constructed bullets (Nosler Accubond, Nosler Long Range Accubond, the Hornady SST, Hornady Interlock, Hornady ELDX, Remington Core-Lokt, etc): 1800-2600fps, ideally. If impact velocity will be above 2600fps, avoid high impact resistance shots like shoulders. If impact velocity falls below 2400fps, and especially below 2000fps, do aim for areas where impact resistance will be higher, particularly shoulders.
•Impact velocity range for soft/frangible bullets (Sierra GameKing, Sierra TMK, Hornady AMAX/ELDM, Hornady A-Tip, Berger Hybrid, etc): 1400-2400fps, ideally and depending on the particular one used. If impact velocity will be above 2400fps, avoid high impact resistance shots like shoulders. If impact velocity falls below 2200fps, and especially below 1800fps, do aim for areas where impact resistance will be higher, particularly shoulders.
•Impact velocity range for copper bullets (Barnes varieties, Hornady GMX and now CX, Nosler E-tip, Hammer varieties, Maker, Peregrine, GS Custom, Patriot Valley Ordinance, Lehigh Defense, etc.): 2200-3200fps, ideally for most designs out there. Honestly, as long as you will impact above 2200fps, I’d be aiming high shoulder to hit the thoracic plexus as well as both lungs. If impact velocity is going to be on the real high end, like above 3000fps, I’d reduce impact resistance so that you don’t simply rip off petals and leave yourself with just a caliber sized hole going through the rest of the animal from just the shank of the bullet.
I think it’s necessary to note too that there are some bullets out there that are a sort of hybrid on some of these designs. The Nosler Partition and Swift A-Frame are two good examples. They feature a thin jacket at the ogive with a soft core to produce excellent initial expansion, and they have a base that is separated by part of the jacket. This keeps the base of the bullet completely separate and together- which allows it to still penetrate after impact. If you look at a cross-section of them, the jacket looks like an “H” or an “A”. They’re essentially a soft point bullet and full metal jacket combined. This can be ideal for those close to mid range/high impact velocity shots.
There are also some tougher constructed bullets that attempt to offer a bit of both worlds as far as being both tough and frangible. The Hornady SST, Hornady ELDX, Swift Scirocco II, Nosler Ballistic Tip, etc. are good examples. They feature jackets that are tapered in thickness and thin out towards the ogive. This enables them to initiate quick expansion at the front of the bullet, yet the jackets are thicker towards the base and/or they have a cannelure or bonding ring that helps adhere the base of the jacket to the base of the core. These are a good compromising design, but still have a higher minimum impact velocity than a true frangible bullet. They still have a tendency to penetrate poorly at high impact velocities, and expand poorly at low impact velocities. I give these types of bullets a rule of thumb impact velocity range still of 1800-2600fps because dipping below will only allow just the most forward section of the bullet to expand, which will result in unreliable and narrow wounding, and going over the max velocity will result in over-expansion and shallow penetration. The ELDX, for example, has a significantly thicker jacket than the ELDM, plus it has the interlock ring, but overall the ELDX is still a relatively soft bullet- in that it’s not actually chemically or electrically bonded and the jackets taper in thickness. The ELDM does not taper in jacket thickness. With too high of an impact velocity, the ELDX can still suffer from poor penetration and over-expansion. Where they differ the most from the ELDM is on the lower end of impact velocity. The thicker jacket and interlock ring will really start holding the bullet together more so than the ELDM at impact velocities dipping below like 1800fps, especially with lower resistance upon impact as well. So the ELDM shines the most if you need a bullet that performs very well still at impact velocities around 2000fps and less, since they still adequately expand down to at least 1400fps.
For close range shots, what you need is a sufficient amount of sectional density (SD), which is the amount of mass behind the frontal area of the bullet. How much is needed will depend on the bullet construction and your expected impact velocity. An ELDX, for example, will still do better with more SD for close range (high impact velocity) shots due to how thin the jackets are at the ogive. If there’s not enough mass behind the ogive, there might not be enough bullet left to do the job after the front starts coming apart on impact.
A bullet with thick jackets, but without tapering, would actually be better with less SD. You’d want less SD to lower the amount of penetration so that you can still achieve sufficient expansion. The Sierra TGK is a good example here. They feature jackets nearly twice as thick as the TMKs, SMKs, and original GKs but without any tapering. The cores in the TGK are also made of a harder lead alloy, which lowers the rate of expansion as well. That type of bullet will come apart at a slower rate having the same thickness at the ogive as at the bearing surface area. With too much mass, it’ll just punch right through before it has a chance to fully expand. Lowering the mass (SD) will lower the rate of penetration and balance out the expansion versus penetration. The same goes for actual bonded bullets too. If you go with a version with too much weight (SD) you’ll end up with more penetration than expansion. Lowering the weight helps balance the two. The same concept applies with copper bullets too, but high impact velocity is even more crucial with those. You want relatively low SD and a high impact velocity for best results with those (light and fast).
An ideal sectional density for softer constructed bullets is above .280, but anywhere above .260 usually proves to be adequate as well, especially with medium to lighter bodied game and if you adjust your shot placement to an area where impact resistance will be less. The extra mass from a higher SD will allow what remains of the majority of bullet to continue penetrating upon impact and have enough material left to still enter the chest cavity and shred/purée the vital organs. This is the type of bullet where heavier for caliber is actually best. This is the type of bullet that goes along with the common mindset of “heavier is better”. Going heavier with a soft/frangible bullet can/will only help you. An ideal sectional density for the tougher constructed bullets would be below .280 when at all possible, especially with the copper varieties, so that you don’t experience over-penetration and insufficient expansion, or expansion that doesn’t occur fast enough before the bullet exits.
9- Bullet Pass-through Versus Non-pass-through
Lastly, I want to specifically touch on bullet pass-through versus non-pass-through. Soft/frangible bullets definitely have their particular limits, but they’re definitely different than the tougher constructed cup and core and copper varieties in regards to how they perform at lower impact velocities. This type of bullet is actually what a lot of long range hunters prefer, but they can also be used effectively at any range, when used properly. They’re much more versatile, and kill much more emphatically. The biggest reason that a lot of the hunters that use them prefer them is because they transfer most, if not all, of their energy into the animal, and without passing through (exiting). Why would you want a bullet to retain all of its weight and then exit? That’s wasted energy that really isn’t doing anything for you, especially if you’re the type of hunter that does indeed prefer to have plenty of energy in their load/ammo.
Some may argue that an exit hole produces a blood trail (which it does), but if the animal bleeds out internally very quickly, as well as drops due to the massive transfer of energy to the CNS, there’s no need for a blood trail. If the bullet doesn’t exit after hitting vitals, you can rest assured it has done its job as far as amount of wounding, as long as it was placed well. A bullet that holds together really well requires very accurate shot placement in order to inflict anywhere near the same level of trauma. If you strike the animal off your mark- for instance between the lungs and liver- you’ll punch through and quite possibly not fatally wound the animal. A frangible bullet that sheds weight and comes apart will still reach out with a shot placement such as that and tear into lungs and/or liver and still fatally wound the animal. That’s an obvious advantage.
As it’s been mentioned several times here so far, with the current bullet selection nowadays and when you know how to properly select and place your bullet, the days of really needing your bullet to pass-through and exit are pretty much gone. I can understand and appreciate the desire for a pass-through though as still being a personal preference, and I can even agree that in some rare circumstances, deep penetration may be needed for certain hunts. That has the tendency to also produce an exit and then subsequently the need for a good blood trail.
I just want to ultimately drive home the point that you can absolutely achieve consistent and emphatic kills, reliably, without a pass-through. It shouldn’t be something that every hunter feels they have to have and achieve. I truly believe it’s just one of those things that’s managed to live on due to old standards and traditions and what hunters continue to hear and be told by many that they should strive for.
Conclusion
Ok, I think it’s time to wrap all this up. So in conclusion, I hope all of this has helped you to better understand terminal ballistics and bullet construction/composition; to understand bullet limitations and how to select the right bullet and the right weight of a particular class of bullet for your particular hunt, and I hope its dispelled many of the common myths and misconceptions out there regarding these things. I wish you all the best luck on your future hunts and continued success.
© 2022 Aaron Peterson. All Rights Reserved.
“The Misconceptions Surrounding Terminal Performance of Bullets.”
U.S. Copyright Registration No. TXu002301231 — Registered January 28, 2022
Published on Hawkeye Ammosmithing.
“The Misconceptions Surrounding Terminal Performance of Bullets.”
U.S. Copyright Registration No. TXu002301231 — Registered January 28, 2022
Published on Hawkeye Ammosmithing.
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