Questions about the irrelevance of energy (ft-lbs)

[bmart2622]

Whats the peak pressure applied from a 156 eol going 2200fps?

 

[Lou270]

Whats the peak pressure applied from a 156 eol going 2200fps?

Depends what you hit but assuming tissue which is mostly water ~32k psi. Incidentally bullet weight or caliber do not matter for hitting something like flesh.

Lou

 

[hereinaz]

Depends what you hit but assuming tissue which is mostly water ~32k psi. Incidentally bullet weight or caliber do not matter for hitting something like flesh.

Lou

Can you point me to information about this? Thanks

 

[Stinky Coyote]

Maybe energy could be called ‘work’ instead?

Ie; engine torque is the work and the hp is the speed of work.

The bullet does have work, and it applies it, to the animal or the hillside, or both. We try to get them to do as much work over the right distance inside animals and less in the hillside.

Still a subjective topic though as we don’t have an objective comparison system or standards to the same levels of inflight ballistics where we land bullets in milk jugs at 2 miles.

The bullet being static and the atmospherics being the variables we’ve learned to solve for in inflight ballistics, the ‘rate of change’ happens in the air.

In terminal ballistics the rate of change happens once the swimming starts and the variables through anaimals and then dirt we don’t have and can’t likely ever solve for.

Maybe in the future we choose a standard swimming media and measure ‘rate of change’ at standard impact velocities and can compare bullets to each other knowing the winners on game already we can find similar options for goals intended? We seem to be a few decades behind inflight ballistics in this regard.

The only numbers we get to work with in terminals ballistics are the starting sd and impact velocity, possibly rpm plays role as well. After the hide though it’s all subjective.

In standardized testing we ‘could’ measure finished sd and distance travelled. Then give ‘rate of change’ data over distance travelled. The bullet holds answers we don’t yet look at. Going 19” and 2.5x expansion tells little objectively.

It’s small math though, the variable is over inches not hundreds or thousands of yards like in inflight ballistics.

Now if bullet started with .264” 123 gr at .252 sd, went 19” and ended with 2.5x expansion (0.66”) and 100 gr for finished sd 0.033 over 19” and landed with 1000 ft/lbs, we have some objective data to work with. We lost 0.011526 sd per inch or 0.0436% per inch (rate of change physically), and transferred 52.63 ft/lbs of ‘work’ per inch.

For imagination purposes in how comparing all against each other this way may look then let’s say that eldm example was now a mono and went 36”, lost only one grain of weight, and only expanded 1.5x. Now it expands to 0.396” and finished sd is 0.111 and so lost 0.0039 sd per inch or 0.014% per inch, and transferred 27.77 ft/lbs per inch. Same 1000 ft/lbs start, same bullet weight and sd to start, just match vs mono construction.

Now imagine if all bullets compared to same standards. We would be able to see what are good 18” bullets that do higher energy transfer per inch and then for larger heavier game even Africa etc we could have goals of 36-48” and whatever makes sense for energy transfer per inch also.

THEN, we could have terminal ballistics calculators built much like our inflight ballistics calculators and we could run the bullet libraries out and find what we want for goals intended. Do we want a .204 Ruger with 35 gr Berger for the perfect 6” bomb for coyotes or want a 3’ mono dumping over 100 ft/lbs per inch for Alaskan moose? We could speak to each other in recommendations on these forums like you want and 18” 50 ft/lb option for those deer size game etc.

But new numbers will need to come with the boxes of bullets and on the boxes of ammo. That are inputs into new terminal ballistics calculators such as Sdrr (sectional density reduction rate) and Etr (energy transfer rate...work transfer rate).

We could make this topic a lot more objective but we’re a long ways off at this point. Decades and many tons of gel behind lol.

A manufacturer will have to be first through the wall and take the bloody nose to get the party started.

It would be good for business though as people will learn and ask for better performing bullets etc. And that would drive development for manufacturers towards better performance which will sell more bullets and everything that wraps them.

The longest threads always seem to be on terminal ballistics and it’s because it’s subjective. Inflight ballistics arguments don’t seem to be a thing anymore. So there’s definitely a gap in this game and no one wants to attack it yet.

We shoot variable sd bullets that deliver work, over very short distances, and we don’t measure any of it in a useful way and make comparable across all bullets we may shoot at game.

 

[Formidilosus]

Maybe energy could be called ‘work’ instead?

Ie; engine torque is the work and the hp is the speed of work.

The bullet does have work, and it applies it, to the animal or the hillside, or both. We try to get them to do as much work over the right distance inside animals and less in the hillside.

Still a subjective topic though as we don’t have an objective comparison system or standards to the same levels of inflight ballistics where we land bullets in milk jugs at 2 miles.

The bullet being static and the atmospherics being the variables we’ve learned to solve for in inflight ballistics, the ‘rate of change’ happens in the air.

In terminal ballistics the rate of change happens once the swimming starts and the variables through anaimals and then dirt we don’t have and can’t likely ever solve for.

Maybe in the future we choose a standard swimming media and measure ‘rate of change’ at standard impact velocities and can compare bullets to each other knowing the winners on game already we can find similar options for goals intended? We seem to be a few decades behind inflight ballistics in this regard.

The only numbers we get to work with in terminals ballistics are the starting sd and impact velocity, possibly rpm plays role as well. After the hide though it’s all subjective.

In standardized testing we ‘could’ measure finished sd and distance travelled. Then give ‘rate of change’ data over distance travelled. The bullet holds answers we don’t yet look at. Going 19” and 2.5x expansion tells little objectively.

It’s small math though, the variable is over inches not hundreds or thousands of yards like in inflight ballistics.

Now if bullet started with .264” 123 gr at .252 sd, went 19” and ended with 2.5x expansion (0.66”) and 100 gr for finished sd 0.033 over 19” and landed with 1000 ft/lbs, we have some objective data to work with. We lost 0.011526 sd per inch or 0.0436% per inch (rate of change physically), and transferred 52.63 ft/lbs of ‘work’ per inch.

For imagination purposes in how comparing all against each other this way may look then let’s say that eldm example was now a mono and went 36”, lost only one grain of weight, and only expanded 1.5x. Now it expands to 0.396” and finished sd is 0.111 and so lost 0.0039 sd per inch or 0.014% per inch, and transferred 27.77 ft/lbs per inch. Same 1000 ft/lbs start, same bullet weight and sd to start, just match vs mono construction.

Now imagine if all bullets compared to same standards. We would be able to see what are good 18” bullets that do higher energy transfer per inch and then for larger heavier game even Africa etc we could have goals of 36-48” and whatever makes sense for energy transfer per inch also.

THEN, we could have terminal ballistics calculators built much like our inflight ballistics calculators and we could run the bullet libraries out and find what we want for goals intended. Do we want a .204 Ruger with 35 gr Berger for the perfect 6” bomb for coyotes or want a 3’ mono dumping over 100 ft/lbs per inch for Alaskan moose? We could speak to each other in recommendations on these forums like you want and 18” 50 ft/lb option for those deer size game etc.

But new numbers will need to come with the boxes of bullets and on the boxes of ammo. That are inputs into new terminal ballistics calculators such as Sdrr (sectional density reduction rate) and Etr (energy transfer rate...work transfer rate).

We could make this topic a lot more objective but we’re a long ways off at this point. Decades and many tons of gel behind lol.

A manufacturer will have to be first through the wall and take the bloody nose to get the party started.

It would be good for business though as people will learn and ask for better performing bullets etc. And that would drive development for manufacturers towards better performance which will sell more bullets and everything that wraps them.

The longest threads always seem to be on terminal ballistics and it’s because it’s subjective. Inflight ballistics arguments don’t seem to be a thing anymore. So there’s definitely a gap in this game and no one wants to attack it yet.

We shoot variable sd bullets that deliver work, over very short distances, and we don’t measure any of it in a useful way and make comparable across all bullets we may shoot at game.

What are you talking about?

Terminal ballistics is one of the most studied, known and replicated things in this field. That the hunting world doesn’t know about or understand legitimate terminal ballistics testing is not because of a lack of information on it- there are reams of papers and research dating back to Vietnam. I can’t think of a single “hunting” bullet made in the last 20 years from a legitimate company, that wasn’t engineered for, and tested in the exact same medium.

 

[Lou270]

Can you point me to information about this? Thanks

Search for dynamic pressure or stagnation pressure in fluid dynamics. There are texts that discuss this but not sure they are online. A very simple thought experiment is why hunting bullets have a similar low velocity expansion velocity irregardless of caliber or ke. It is because the pressures generated at impact need to be higher than the yield strength if copper/lead. If you hit something hard like steel or bone the impact pressures are enough to deform the bullet. If you hit something soft like gel or a tissue they behave like a fluid and the higher velocity impacts increase the pressure as cant get out of way fast enough. Above 4000 fps even steel can shatter impacting something soft due to the high pressures generated

Lou

 

[bmart2622]

Depends what you hit but assuming tissue which is mostly water ~32k psi. Incidentally bullet weight or caliber do not matter for hitting something like flesh.

Lou

So what does that wound channel look like and what is the max effective range of 32kpsi?

 

[hereinaz]

So what does that wound channel look like and what is the max effective range of 32kpsi?

There is little need to predict from that… that’s making it way more complicated than it needs to be. As Form said, there are articles, papers, experiments, and lots of other photographic information to know what a particular bullet will do at what velocity.

 

[bmart2622]

There is little need to predict from that… that’s making it way more complicated than it needs to be. As Form said, there are articles, papers, experiments, and lots of other photographic information to know what a particular bullet will do at what velocity.

That was the point I was getting at. Seems a lot easier to stay above the minimum velocity needed gor expansion and be done...but then people can't make energy arguments

 

[Skydog]

@Formidilosus - Based on your research, what have you concluded about the idea of hydrostatic/hydraulic shock, pressure waves, etc.? Is there any evidence to support the idea that there can be some type of indirect damage/trauma throughout the animal's body in addition to the direct damage from the impact of the bullet/wound channel? Or are these just more myths - like "knock down power" and "wallop" - that need to be relegated to the dust bin?

And I'm not asking if it can be objectively measured, defined, or used as a metric for predicting terminal performance. I'm just asking if it's a thing.

Thank you!

 

[The Guide]

@Formidilosus - Based on your research, what have you concluded about the idea of hydrostatic/hydraulic shock, pressure waves, etc.? Is there any evidence to support the idea that there can be some type of indirect damage/trauma throughout the animal's body in addition to the direct damage from the impact of the bullet/wound channel? Or are these just more myths - like "knock down power" and "wallop" - that need to be relegated to the dust bin?

And I'm not asking if it can be objectively measured, defined, or used as a metric for predicting terminal performance. I'm just asking if it's a thing.

Thank you!

It has been cover and shared from the research papers that hydrostatic shock does not travel past the wound cavity (temporary and permanent) nor does it follow the blood vessels to affect other areas.

Jay

 

[Skydog]

It has been cover and shared from the research papers that hydrostatic shock does not travel past the wound cavity (temporary and permanent) nor does it follow the blood vessels to affect other areas.

Jay

So, it’s a thing (sort of) but limited only to direct trauma at the wound channel. Thank you for the clarification. I’ve seen the concept put forth that since tissue is mostly water, the shock/pressure waves can travel throughout the animal (via all that water in the tissue) and cause trauma (e.g neural/brain) even far from the wound channel itself.

 

[Bugger]

It shouldn’t take more than the first 10 pages of the 223 kill thread when guys started talking about maximum distances. I just laughed at the guy who claimed 1000 yards, but clear up to 800 yards guys have killed 100s of elk. lol

Also didn’t happen.
Still waiting for you to cite/quote/link where people say it’s a 700 yard hammer and then you thrash em’ with the old 22 hornet argument.

 

[Thegman]

I'm a recent convert (at least in theory) to the concept of using smaller calibers with light fragmenting bullets on big game. So, bear with me if these are dumb questions. I'm still having to work through and unlearn some previously held beliefs about "knockdown power".

I have read pages and pages of threads here at RS and I feel like I have a pretty good grasp on the concept, but...

I have read many comments stating things like "energy is a totally irrelevant/meaningless metric in terminal performance or effectiveness on game", the "myth of energy", etc.

However, I also see comments from advocates of the small caliber/fragmenting bullet school, that state things like "you don't want the bullet to exit because you want the full energy dump inside the animal and not on the dirt behind the animal" when discussing penetration. Statements like these seem to imply that there is some significance/benefit to having more energy transfer to the animal, otherwise why would one care if some of that energy is lost due to over-penetration/exit?

How do you square the idea of energy being totally irrelevant with also claiming the advantages of a full energy dump from the bullet? This seems inconsistent and contradictory. If energy is really irrelevant, why do I care if some of a bullet's energy is "wasted" on the dirt after exiting the animal? How is energy wasted if it is irrelevant to begin with? And why is more of an energy dump better than less of an energy dump if energy is truly irrelevant?

All other things being equal, is there or is there not an advantage of a 1500 ft-lb "dump of energy" versus a 1200 ft-lb "dump of energy"?

Hope my questions make sense...

My take on your points...fwiw.

You're correct that a bullet that doesn't exit, by definition, "dumped" all its energy in the animal. The terminal results of that "energy dump" vary from one bullet design to another, including different weight bullets of the same design.

Some designs, like the 77TMK, seem create a lot of damage per unit of energy, so to speak. Other designs maybe less, or even more. So there's really no direct correlation of amount of energy to terminal performance as far as that goes, without specifics about the bullet.

About the closest comparison I can think of for your question might be something like a comparison between say a 75ELDM vs a 155 ELDM impacting -at the same velocity-. The 155 has a little more than 2x the energy, and from the pictures I've seen, does quite a bit more damage, which is most likely due to it having more KE, and mass, to impart said damage. For a lot of hunters, maybe more damge than needed or desirable.

Bottom line, yes, more KE does provide the -potential- to create more damage with respect to terminal performance, but in and of itself, it's not instructive as a predictor of performance.

Much more instructive to know the specific bullet and its impact velocity as a predictor of performance. You're right that KE is ultimately responsible for the damage in each specific case after the fact, but largely useless for the prediction of performance.

 

[Stinky Coyote]

What are you talking about?

Terminal ballistics is one of the most studied, known and replicated things in this field. That the hunting world doesn’t know about or understand legitimate terminal ballistics testing is not because of a lack of information on it- there are reams of papers and research dating back to Vietnam. I can’t think of a single “hunting” bullet made in the last 20 years from a legitimate company, that wasn’t engineered for, and tested in the exact same medium.

See it how you see it. I just gave how I see it.

You can argue that the wounds have been studied at length and I won’t argue back. Same goes for general gel testing for depth and diameter expansion ratio.

I simply see it as, all this time, most have been looking at the wrong stuff if goals are to take terminal ballistics to an objective level of comparison and understanding that meets inflight ballistics in the 21st century. My proof is in every single 50 page thread still in every forum every year. We are ignoring much while focusing on the wrong stuff when the bullet itself, which does the work, is ignored and its rate of change is only looked at from a crayon grade level while inflight is at nasa levels lol.

We carry on any further here and the subjectivity will boil over and prove it once again.

We haven’t figured out all the ways to skin this cat yet. It’s like a brand new cat we’ve never seen before.

And conversations remaining constructive with others ideas on how to get the swimming ballistics more objective can only help.

You sayin we’ve takin this as far as we can go? I completely disagree.

No biggie. It won’t be the last thing we don’t see the same. Others can have thoughts on things that others haven’t thought of, always a good thing in name of progress.

Aren’t you tired of trying to explain to folks why the little tiny match pills are so deadly in endless subjective iterations? Do you have to do that with inflight ballistics now? No, you don’t.

 

[Skydog]

Bottom line, yes, more KE does provide the -potential- to create more damage with respect to terminal performance, but in and of itself, it's not instructive as a predictor of performance.

Much more instructive to know the specific bullet and its impact velocity as a predictor of performance. You're right that KE is ultimately responsible for the damage in each specific case after the fact, but largely useless for the prediction of performance.

I think this does a great job of summarizing the key takeaway from these 8 pages of posts.

 

[hereinaz]

So, it’s a thing (sort of) but limited only to direct trauma at the wound channel. Thank you for the clarification. I’ve seen the concept put forth that since tissue is mostly water, the shock/pressure waves can travel throughout the animal (via all that water in the tissue) and cause trauma (e.g neural/brain) even far from the wound channel itself.

Others can correct me as I am technically incorrect or off base, but when it comes to the way bullets cause damage, it’s complicated. This is my best understanding and lay person explanation of how “water” and tissue elasticity come into play for wound.

The “shock” of a bullet can permanently disrupt CNS, but I think it will happen in far fewer circumstances without actual physical damage by bullet or bone shrapnel. I don’t have a lot of personal experience but it seems to me the times when an animal drops like a sack of potatoes, but then gets up and runs away are when the hydrostatic shock temporarily incapacitates the animal like a boxer taking a head shot.

The only “indirect” tissue damage is from the shock/temporary cavitation that exceeds the elasticity of the tissue. Tissue is highly elastic. You see blood shot muscle tissue surrounding the permanent wound cavity, but the majority of that is damage to the thin walled capillaries, not the muscle tissue itself. It is essentially a really bad bruise.

Read medical papers on how much tissue surgeons should remove to understand that. Basically, surgeons have found that they were removing far more tissue than necessary from patients and only needed to remove tissue from actual the wound channel.

It’s like stretching a rubber band, if you stretch is slow, it won’t break until you exceed its elasticity. Muscle tissue is very elastic and strong by nature.

However, if you stretch a rubber band or muscle really, really fast, it will break because it can’t stretch fast enough. This is why very high velocity impacts have larger tissue damage. But, the area of tissue stretching doesn’t go very far.

This is why high velocity monos can be very damaging and liquify without the other effects of a highly fragmenting bullet and only leave a small wound channel when velocity drops.

Another factor to tissue destruction (I think is more theoretical) when stretched is like tossing a filled water balloon into a bucket of balloons and that starts them all popping. While tissue is stretched, if there is something that causes a tear into tissue, then a cascade of tearing occurs along the path of bullet pieces that are like balloons popping in in a bucket.

This happens at high velocity when the lungs gets liquified because of the higher water content in the lungs with blood dispersed through the tissue as it exchanges gasses and its less dense tissue structure.

As an aside, this is why the “clear ballistics gel” that most YouTubers use is practically useless at representing the effect of living tissue, especially at lower velocities. It has ZERO water content. FBI ballistics gellatin is 10% gel and 90% water, and calibrated to density. It’s basically a thick jello without flavor or color.

Also, another paradox is that at higher velocities, the water in the tissue is “harder” and causes the bullet to break up more. It’s like you jumping into the pool from 30 feet vs 3 feet. The water is “harder” when you hit it the faster you go, which is the same for a bullet. @Lou270 can explain it technically.

A simple example to get the concept is “oobleck” which is corn starch mixed with water. You can pour it out like thick syrup. But, if you punch a bowl it is like a rock.

That phenomenon is why highly fragmenting bullets are less likely to exit at close range/high velocity because they break up into small pieces and on the flip side are more likely to get pass through at longer range/lower velocity.

If you take all of the physical phenomena above, THAT is another reason why using “energy” is not a good metric. The energy of a fast/small highly fragmenting might be enough to incorporate all of this damage. But, the higher energy of a large/slow non fragmenting bullet only cuts through like an arrow.

The mechanism of tissue damage is highly complex with many variable. such that energy is practically useless as a metric to tell anyone what the damage will look like.

 

[TaperPin]

Also didn’t happen.
Still waiting for you to cite/quote/link where people say it’s a 700 yard hammer and then you thrash em’ with the old 22 hornet argument.

So you want me to waste my time to find the discussions, then what? You go silent and snicker to yourself for getting me to waste the time? Lol

 

[hereinaz]

See it how you see it. I just gave how I see it.

You can argue that the wounds have been studied at length and I won’t argue back. Same goes for general gel testing for depth and diameter expansion ratio.

I simply see it as, all this time, most have been looking at the wrong stuff if goals are to take terminal ballistics to an objective level of comparison and understanding that meets inflight ballistics in the 21st century. My proof is in every single 50 page thread still in every forum every year. We are ignoring much while focusing on the wrong stuff when the bullet itself, which does the work, is ignored and its rate of change is only looked at from a crayon grade level while inflight is at nasa levels lol.

We carry on any further here and the subjectivity will boil over and prove it once again.

We haven’t figured out all the ways to skin this cat yet. It’s like a brand new cat we’ve never seen before.

And conversations remaining constructive with others ideas on how to get the swimming ballistics more objective can only help.

You sayin we’ve takin this as far as we can go? I completely disagree.

No biggie. It won’t be the last thing we don’t see the same. Others can have thoughts on things that others haven’t thought of, always a good thing in name of progress.

Aren’t you tired of trying to explain to folks why the little tiny match pills are so deadly in endless subjective iterations? Do you have to do that with inflight ballistics now? No, you don’t.

The reason that these threads continue to exist isn’t for lack study or evidence, it is because hunters as a whole cling to myths like wallop and bullet proof elk. So few are willing to read the papers themselves or accept the facts derived from them. Or, if they see the .223 for bear, elk… thread they ignore it or disbelieve the hundreds of pages.

Every one is free to believe things, even if they are untrue.

This is a perfect example—you gloss over the fact that there are papers, studies, demonstrations, and evidence. You are perpetuating these threads by ignoring established explanations for terminal ballistics?

There are multiple studies to determine exactly where the damaged tissue ends and viable tissue begins. That is 100% applicable to understanding the effect on game tissue.

There is no huge debate among surgeons about the effect of bullets in tissue. Sure, they are refining techniques, but the field of terminal ballistics has resolved the questions at the level important for hunters.

It’s curious that you didn’t ask where the studies are or find them so that you can see that terminal ballistics has been studied and answered the questions posed in these threads.

The only thing left to do is educate hunters to the reality.

 

[hereinaz]

So you want me to waste my time to find the discussions, then what? You go silent and snicker to yourself for getting me to waste the time? Lol

LOL, put up or shut up, isn’t that the saying? I was waiting for you to find me the 22 Hornet threads too.

Why are you OK wasting our time reading your comments but you don’t want to waste your time? Hmmm. Suspicious,

There is no rule against amusement, sarcasm, twisting virtual titties. You are here for your pleasure and amusement. Me too sometimes It’s ok, keep at it. I am just calling it the way it is. You admit you throw stuff out for your amusement factor, so you own it like a big boy. That’s admirable. Humor on the internet is not easy.

I am a little bored today…

This is a PSA so people don’t take you too seriously. Which is unfortunate because you have started helpful posts and added beneficial information in many others.

Just making it clear for people here who are trying to learn. Take anything @TaperPin says with a grain of salt. If it is annoying or confrontational, laugh and move along. He is a funny guy when you know he is there for the reaction. He actually does a good job poking the sacred cows like the court jester. Everyone needs that from time to time.

If it’s not annoying, confrontational or confusing, he probably has a good point.