Does Energy have the potential to affect terminal performance?

[10E]

I’ve heard this loosely parroted a few time across the web. “Energy is a useless number in terminal performance”. Is this a factual statement? Has the science been settled? Can its potential effect be so quickly deemed useless? Perhaps it is more misunderstood or unknown?

The purpose of this post:

1. A lively debate to the questions above.

2. To not spread possible misinformation either way on the matter, and to increase the knowledge base of this community. We know, we don’t know etc.

3. Come to some consensus through logical debate.

A few statements that we can hopefully agree on. Energy (in terms of projectiles fired out of center fire rifles) can only be increased by increasing a projectiles mass, velocity, or both mass and velocity.

Terminal ballistics is a sub-field of ballistics concerned with the behavior and effects of a projectile when it hits and transfers its energy to a target.

A few arguments to squash right off the bat that will quickly derail this discussion and get us off in the weeds.

These will fall under arguments that are not being made:

1. This is not an argument of whether or not the energy was necessary to kill an animal. If killing the animal was the only solution to the problem a sharpened stick would kill/answer the solution just as well as a nuclear bomb.

2. This is not an argument about bullet construction. This is a well known fact that bullet construction plays a huge part in the transfer of potential energy into the target.

3. This is not an argument solely about bullet diameter, bullet mass, bullet velocity, sectional density, or target medium as all have the potential to affect terminal performance. That is not in any particular order of importance.

4. This is not at all an argument that high energy always equals high terminal performance, but rather that higher energy has a higher potential to affect terminal performance. (More work that can potentially be done)

5. This is not an argument that energy figures should be held above or prioritized over any other variable. That being said no single factor should be held above all else as the extremes in any category seem to be where can problems arise.

6. Let’s agree to refrain from from using extreme hypotheticals or figures, I.e. 1 million foot pounds arguments. Let’s try to keep this within the available caliber/ mass/ velocity ranges current center fire rifles are capable of producing.

 

[BLJ]

Nothing to add but in for updates.

 

[Formidilosus]

I’ve heard this loosely parroted a few time across the web. “Energy is a useless number in terminal performance”. Is this a factual statement? Has the science been settled? Can its potential effect be so quickly deemed useless? Perhaps it is more misunderstood or unknown?

The purpose of this post:

1. A lively debate to the questions above.

2. To not spread possible misinformation either way on the matter, and to increase the knowledge base of this community. We know, we don’t know etc.

3. Come to some consensus through logical debate.

A few statements that we can hopefully agree on. Energy (in terms of projectiles fired out of center fire rifles) can only be increased by increasing a projectiles mass, velocity, or both mass and velocity.

Terminal ballistics is a sub-field of ballistics concerned with the behavior and effects of a projectile when it hits and transfers its energy to a target.

A few arguments to squash right off the bat that will quickly derail this discussion and get us off in the weeds.

These will fall under arguments that are not being made:

1. This is not an argument of whether or not the energy was necessary to kill an animal. If killing the animal was the only solution to the problem a sharpened stick would kill/answer the solution just as well as a nuclear bomb.

2. This is not an argument about bullet construction. This is a well known fact that bullet construction plays a huge part in the transfer of potential energy into the target.

3. This is not an argument solely about bullet diameter, bullet mass, bullet velocity, sectional density, or target medium as all have the potential to affect terminal performance. That is not in any particular order of importance.

4. This is not at all an argument that high energy always equals high terminal performance, but rather that higher energy has a higher potential to affect terminal performance. (More work that can potentially be done)

5. This is not an argument that energy figures should be held above or prioritized over any other variable. That being said no single factor should be held above all else as the extremes in any category seem to be where can problems arise.

6. Let’s agree to refrain from from using extreme hypotheticals or figures, I.e. 1 million foot pounds arguments. Let’s try to keep this within the available caliber/ mass/ velocity ranges current center fire rifles are capable of producing.

These are incorrect questions.

Really what someone that is concerned if ft-lbs of energy is a number that has practical use in choosing a bullet or cartridge is- will fit-lbs of energy tell us about what kind of wound will be made?

 

[Billy Goat]

Ok, I made this the other day, however I knew it wasn't going to help the discussion.


It's still not going to help the discussion, but ima post it anyways.

 

[hereinaz]

Energy by itself isn't as useful as other numbers when comparing different sized bullet, bullets of different construction, etc. The "energy" number is based on the relationship between velocity and mass. Whether a bullet expands doesn't depend on mass, it only depends on velocity. So, by talking "energy" you are two relationships away from the only thing you need to know.

The useful ways to compare bullet terminal performance is bullet construction and velocity. They are the two giant factors, and everything else is of much smaller effect.

For instance, we know that all Berger hunting bullet construction is designed to reliably "work" down to 1800 FPS. For any Berger bullet, we can say that the bullet will perform in broadside vitals at 2000 FPS with a variation of A in penetration and B width of wound channel depending on the mass of the bullet. And, the variation isn't even of a big material difference.

Of course, this assumes that you have been persuaded by the mountain of evidence that a 77 grain "explosive match" bullet causes massive amounts of trauma, even more than mono bullets more than twice its weight.

Energy isn't useful as a broad category, because the difference in energy between the 77 grain and a 235 grain bullet is going to be massive, even though the actual damage won't correlate to damage as closely as velocity. At most, the difference in energy is related to the variation in A/penetration and B/width of wound channel.

And, to use energy the shooter has to use a bullet specific number that is just the mass X velocity, so why not just use velocity. Just energy is meaningless, because a 235 grain bullet can have more energy than a 77 grain bullet, but the 235 grain bullet can fail below 1800 FPS but the 77 grainer is still above 1800 FPS and will fragment.

 

[Drenalin]

Energy transfer certainly occurs, but its numerical value doesn’t tell you much about the wound created. It may be able to tell us something about penetration depth but cannot describe the wound shape, which I would say is the bigger factor once we achieve enough penetration to reach the vitals. As @hereinaz said above, bullet construction and velocity are the things that should concern us.

I wouldn’t say I know what I’m talking about, this is just my perception based on what I think I know.

 

[hereinaz]

Energy transfer certainly occurs, but its numerical value doesn’t tell you much about the wound created. It may be able to tell us something about penetration depth but cannot describe the wound shape, which I would say is the bigger factor once we achieve enough penetration to reach the vitals. As @hereinaz said above, bullet construction and velocity are the things that should concern us.

I wouldn’t say I know what I’m talking about, this is just my perception based on what I think I know.

Yes, energy alone can't tell you anything about the wound channel. People can use full "energy transfer" but that gets into bullet construction as well. And, the differences between bullet construction vs. bullet energy can be huge.

Think of the perfect mushroomed bullet that catches on the offside hide with excellent weight retention that completely transferred its energy. And, two, the "explosive match bullet" that "dumps" its energy after a few inches of penetration and nothing penetrates to the offside hide.

 

[OutdoorEdventure]

Yes but needs A L O T of clarification.

 

[ThatDUDE]

I used to subscribe to the belief that 1500 ft/lbs of energy was the minimum needed to kill elk, and 1000 ft/lbs was the minimum for deer. I was self-taught regarding hunting, and all of this information came from reading articles in many popular hunting and shooting magazines. I started my journey on Rokslide 2 years ago. My first post's were about 300 Win Mags, 30-06's, and 300 WSM's for elk hunting. That's what I had read was needed.

Well I quickly stumbled onto all the "blank caliber for deer, elk, and bear threads". My mind was blown to say the least.

I guess I am just a simple minded country boy, but seeing hundred's of photos of elk, deer, and bears killed with cartridges that had far below the "required minimum ft/lbs of energy" caused me to immediately discount all those required minimums. To my simple mind there is too much actual photo and personal information on Rokslide from hundreds of other "non-gun" writers that proves to me energy is not a legitimate measure of killing ability in a cartridge. Just my limited 2 cents.

 

[Jason Snyder]

A much more useful investment of mental energy would be to understand how different bullets perform, the velocity they need to perform correctly, and how chosen shot placement with different bullets will determine the lethality of the shot.

 

[MuleyFever]

I'm going to refrain from a meme, but this again?

 

[jjohnsonElknewbie]

Think of the perfect mushroomed bullet that catches on the offside hide with excellent weight retention that completely transferred its energy. And, two, the "explosive match bullet" that "dumps" its energy after a few inches of penetration and nothing penetrates to the offside hide.

Assuming similar shot placement in the vitals “behind the shoulder”, “in the crease”, “high shoulder”, etc…, both bullets in this example likely kill the critter. However, the rapidly upsetting/fragmenting bullet will likely deliver a larger overall wound channel(s).

Form has mentioned this before, and it comes down to personal preference ie- if you care about penetration more and always want an exit wound, pick the bullet to achieve this objective understanding you will compromise on wound channel size. This also goes for guys who want to prioritize decreasing meat loss due to fragmentation and bloodshot meat.

If you want maximum wound channel and are indifferent to exit wounds pick a thinner jacketed bullet designed to upset/fragment ie- match style bullets.

Neither of these are dependent on energy or head stamp.

 

[jjohnsonElknewbie]

I’ve heard this loosely parroted a few time across the web. “Energy is a useless number in terminal performance”. Is this a factual statement? Has the science been settled? Can its potential effect be so quickly deemed useless? Perhaps it is more misunderstood or unknown?

All I know is that manufacturers publish the minimum velocity required for a given bullet to expand reliably. On the contrary, I’ve never seen manufacturers publish a minimum energy figure for expansion.

 

[Thegman]

I’ve heard this loosely parroted a few time across the web. “Energy is a useless number in terminal performance”. Is this a factual statement? Has the science been settled? Can its potential effect be so quickly deemed useless? Perhaps it is more misunderstood or unknown?

2. This is not an argument about bullet construction. This is a well known fact that bullet construction plays a huge part in the transfer of potential energy into the target.

You're right that Kinetic Energy is obviously important to some extent. A bullet with a velocity of zero has zero kinetic energy and has zero ability in terms of terminal performance. It is kinetic energy that ultimately allows the bullet to reach the target and then cause tissue disruption and killing.

That said, IMO, your #2 above can't be separated from the discussion of kinetic energy, as bullet construction has as much to do with the final answer as does kinetic energy.

Talking about KE without talking about the bullet as well is like talking about the wattage of a light bulb without talking about its spectrum. One can see better under a 10 watt bulb that emits a 3.5K visible light spectrum than a 100 watt bulb that's in the infra-red spectrum. Light bulb construction matters..as does bullet construction.

So when it's said "kinetic energy has nothing to do with terminal performance", I agree, that's not technically correct, but I really don't take that as its meaning. I think the point is the other variables, especially the bullet and its construction have to be taken into account to come up with a meaningful answer regarding terminal performance.

A better question might be, "For (this particular bullet), how much kinetic energy is required to get (this particular terminal performance). The answer will generally be bullet dependent, I think.

 

[Formidilosus]

A better question might be, "For (this particular bullet), how much kinetic energy is required to get (this particular terminal performance). The answer will generally be bullet dependent, I think.

That’s correct and that is the problem. Correct upset velocity is the determiner, not Ft-lbs energy. Hornady ELD-M’s and ELD-X as well samples all need 1,800fps to reliably upset- that is regardless of of caliber or weight. From .224 to .338 that all need the same impact velocity. Yet the ft-lbs of energy for each bullet at 1,800fps impact is all over the map. From 550 ft-lbs for a .224 75gr ELD-M, to 2,054 Ft-lbs for the .338 cal 285gr. Yet, the both those bullets upset properly at 1,800fps.


Ft-lbs of energy is a “useless” metric because it doesn’t tell anyone anything about what a bullet will do in tissue. To know know what a bullet does in tissue it must be shot into tissue or properly calibrated tissue simulate at varying impact velocities and have the wounds that are created measured.
Once you do that, it does not matter how much “energy” it had or didn’t have. The wound is what matters.

 

[Tmac]

Yes, energy is a fairly useless number in terminal performance imo. The common measure used in hunting in the USA is ft. lbs. It’s an attempt to describe energy. Imo it‘s a made up number, much like HP in engines. We take two known actual measurements, mass in grains and velocity, then we put it in a formula and say this develops 2,100 ft lbs or whatever. So it sounds big, but what does it tell me? But it is about the damage the projectile does to the animal. That is the critical real thing to pay attention to and what energy can’t tell us. Ergo my focus on the known measurements, weight/velocity, and then bullet construction.

I always say if ft lbs killed, arrows wouldn’t. What I have learned to pay attention to is my bullet and it‘s impact velocity. Bullet weight and construction, and then the velocity window it performs in. Those are the best indicators of what terminal performance will be. Energy does give one some idea of the potential that exists in terms of terminal performance I suppose. But often we are comparing bullets differing by a few thousands of an inch in diameter and 30-50-… grains of weight in animals that weigh 200-700 or more pounds. I'd suggest once one is to a sane minimum bullet weight/diameter, bullet construction becomes the critical component to understand. Get that right and use it in it‘s velocity window and kill stuff.

 

[eric1115]

That’s correct and that is the problem. Correct upset velocity is the determiner, not Ft-lbs energy. Hornady ELD-M’s and ELD-X as well samples all need 1,800fps to reliably upset- that is regardless of of caliber or weight. From .224 to .338 that all need the same impact velocity. Yet the ft-lbs of energy for each bullet at 1,800fps impact is all over the map. From 550 ft-lbs for a .224 75gr ELD-M, to 2,054 Ft-lbs for the .338 cal 285gr. Yet, the both those bullets upset properly at 1,800fps.


Ft-lbs of energy is a “useless” metric because it doesn’t tell anyone anything about what a bullet will do in tissue. To know know what a bullet does in tissue it must be shot into tissue or properly calibrated tissue simulate at varying impact velocities and have the wounds that are created measured.
Once you do that, it does not matter how much “energy” it had or didn’t have. The wound is what matters.

I'd guess a .224 75 grain at 1800 fps/550 ft lb is likely a lot more effective than a .338 285 grain at 934 fps/550 ft lb. But I've never shot an animal at 3k+ yards with a .338 to find out

 

[Formidilosus]

I'd guess a .224 75 grain at 1800 fps/550 ft lb is likely a lot more effective than a .338 285 grain at 934 fps/550 ft lb. But I've never shot an animal at 3k+ yards with a .338 to find out

Of that you can be sure. A 77gr TMK at 300 and something ft-lbs of energy penetrates 16” plus inches even through the dreaded elk “shoulder”, and produces coke can width wounds.

 

[eric1115]

Of that you can be sure. A 77gr TMK at 300 and something ft-lbs of energy penetrates 16” plus inches even through the dreaded elk “shoulder”, and produces coke can width wounds.

But ENERGY! Ft lbs sound so scientific! How can they not be a measure of performance?

 

[Marbles]

Here is an overly long winded answer I posted in another thread.



Well, specifically, kinetic energy (KE). Energy is a much broader term and described by many different equations based on the form in question. Yes, I am nit picking, but physics is about details, ignoring the details converts it into mysticism.

The problem is KE does not translate directly into energy transferred to the target, much less how that energy is transferred. Only energy transferred counts, and efficiency of that transfer for destruction of tissue counts even more. A rubber bullet will transfer more of its KE into a flesh target than an FMJ, but I would much rather be hit with the rubber bullet if I had to pick. A sharp broadhead transfers less of its energy into a target than a dull broadhead, but the sharp head kills better.

The KE of a projectile only predicts potential, in the way the horsepower of an engine only predicts potential speed. Much like the actual speed of the vehicle is influenced by more than the engine HP, the actual killing potential of a bullet is influenced by many things other than KE. Just like if you put bald summer tires on a Porsche 911 and race it against my Corolla with premium winter tires on this sub 0 day with ice and snow covered roads, my Corolla will win because even though it is the inferior vehicle in every way, it can put more power to the pavement (both acceleration and breaking) due to the interface. So, to with KE vs bullet selection.

To extend the example further, yes a simple tire swap will put the Porsche stomping the Corolla, however the Corolla gets me to work in a timely and reliable manner without fail, what practical functionality do I gain if I go out and buy a 911? The same applies to barrel length, velocity, and cartridge selection. Put differently, nothing about the Porsche obviates the need for proper tire selection, so too nothing about increased velocity obviates the need for proper bullet selection.

Theory, used in a bottom up fashion, frequently fails to explain realty because of how complex the world is. Theory generated in a top down fashion, then applied to similar circumstances to predict an outcome tends to be more accurate because while we may not fully understand the phenomena, what we don't understand is still accounted for through the testing that generated the theory.