Momentum vs Kinetic Energy visualized, no mention of lethality

[35 Whelen]

You are discussing things without any basic understanding of how bullets work or the meaning of the terms you use. I have tried to make it simple for you. I hope my explanation helps.

Oh...you mean how bullets work, like this? Just a small handful of the bullets that I recovered from game from 40 years of hunting??









Or maybe these that I cast, loaded, shot and recovered from game?









Is that what you mean by "understanding how bullets work"?

Everything else submitted here so far, without exception, has been speculation and hypothesis based on bloviated math.

But, I understand, because as a teenager and new hunter, I religiously studied ballistics charts and worshipped at the altar of bullet energy. Then I actually started killing things, digging out bullets and realized that math has nothing to do with how effective or ineffective a bullet performs.

35W

 

[d2wing]

Nice pictures. Merry Christmas.

 

[mcb]

Oh...you mean how bullets work, like this? Just a small handful of the bullets that I recovered from game from 40 years of hunting??

View attachment 875066

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Or maybe these that I cast, loaded, shot and recovered from game?

View attachment 875070

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Is that what you mean by "understanding how bullets work"?

Everything else submitted here so far, without exception, has been speculation and hypothesis based on bloviated math.

But, I understand, because as a teenager and new hunter, I religiously studied ballistics charts and worshipped at the altar of bullet energy. Then I actually started killing things, digging out bullets and realized that math has nothing to do with how effective or ineffective a bullet performs.

35W

Takes more math than a ballistic table.



The above video was generate from pure math. A computer model of a jacketed AP projectile hitting an aluminum plate at an oblique angle. Just because the hunting world lacks the resources to do it does not mean it can't be done.

ETA: Remember this thread was not really about terminal ballistics it was about the inseparable relationship between Momentum and Kinetic Energy.

 

[d2wing]

Once in awhile a person must remember that Much of the U.S. big game was wiped out by the 1880 before high velocity cartridges were invented. By 1862 enough of once plentiful game was wiped out in Minnesota to cause a great native uprising due to lack of wild game in settled Southern Minnesota. Over 1000 people were killed. When I was young there were so few deer and other game they didn't have a season one year.

 

[Jim Watson]

ETA: Remember this thread was not really about terminal ballistics it was about the inseparable relationship between Momentum and Kinetic Energy.

Well, yeah, they are both computed from mass and velocity, the equations are all there is. And if you are not looking for a correlation with terminal ballistics, then why bother?

When I was young there were so few deer and other game they didn't have a season one year.

When I was young, killing a deer was a lifetime accomplishment. Turkey? Forget about it.
Now it is more like going to the grocery store.

 

[94045]

Don't blame math for poor mathematicians.
Reality is defined by math.
But first you have to ask the right question.

 

[Kleanbore]

Is that what you mean by "understanding how bullets work"?

No. You missed the point entirely.

Everything else submitted here so far, without exception, has been speculation and hypothesis based on bloviated math.

No, not everything .

 

[tipoc]

Just another data point showing momentum and energy are poor parameters to define lethality...

Those figures are not "parameters to define lethality" they are not intended to be poor or not. If a person thinks that they are they are making an error. As I and other have said here they are part of the picture but only part.

"I pointed that out for the sole reason that I hate when people quote muzzle energy as the "proof" that one cartridge, or loading, is superior to another. Terminal ballistics is way too complicated to reduce to one or two figures."

OK. But as was explained earlier both momentum and energy do play a role. Maybe it's useful to explain that role and it's limitations in selecting a bullet for a particular job...add in the rest of what's useful to look at.

 

[35 Whelen]

Not so fast. Energy is what causes the bullet to deform or expand.

Then.....

NO!

No one has said that energy determines bullet expansion.

See, here we have an example of nothing more than arguing semantics.

If energy causes bullet expansion, as you state, then the amount of energy would in turn determine the degree of expansion which it does not. (See the example I posted above)

No. You missed the point entirely.

You tell me I don't understand how bullets work, I submit examples of recovered bullets that have worked, then you tell me I "missed the point entirely.".

So at this point, I'm not even sure there IS a point other than some of those among us attempting to determine lethality by use of spreadsheets and calculations. And if that's your thing, more power to you. I prefer field experience; both mine and others.

35W

 

[tipoc]

A typical .44 Magnum load: 250 gr. SWC @ 1150 fps; Energy = 734 fp
A typical .22 Hornet load: 46 gr. SP @ 2700 fps; energy - 744 fp

Now, does anyone REALLY believe these two projectiles will kill exactly the same? Absurd.

Energy does NOT initiate bullet expansion. Energy does NOT create hydrostatic shock. Math. Math. Math. That's all energy is. Period.

Step AWAY from the keyboard and go hunting.

Myself and others explained earlier why this point of view is off base. We explained what energy is and why it's needed for both expansion and penetration. We also explained why they are not the only factors.

"Now, does anyone REALLY believe these two projectiles will kill exactly the same? Absurd."

Well we know that those rounds will both kill and do so very well. Just not the same animals. This is where those "other factors" mentioned come in, like selecting the right gun for the job you plan to do and a properly constructed bullet for that job. Hunting prairie dogs at 300 yards with a Model 29 S&W is likely not the right choice

 

[Kleanbore]

If energy causes bullet expansion, as you state, then the amount of energy would in turn determine the degree of expansion which it does not.

Nope!

Energy causes expansion and deformation, period. Other things determine how the bullets expand.

ou tell me I don't understand how bullets work, I submit examples of recovered bullets that have worked, then you tell me I "missed the point entirely.".

Someone else said that, and you replied with some photos that explained absolutely nothing about how the bullets worked. They simply showed that they did..

Back to energy. No, energy does not kill.

But energy is what changes the shape of metal, and what tears and fragments metal.

Let's forget the expansion of bullets for a moment, and let's talk about metal fabrication.

When we cut, abrade, roll form, bend, swage, draw, hammer form, stamp, forge, stretch, extrude, or pull-trude metal we do so by applying force over distance.

Force times distance is defined as energy.

The same thing happens when we fire a soft bullet into a target, or a bullet that is designed to expand.

So at this point, I'm not even sure there IS a point other than some of those among us attempting to determine lethality by use of spreadsheets and calculations.

Has someone tried that?

 

[tipoc]

If energy causes bullet expansion, as you state, then the amount of energy would in turn determine the degree of expansion which it does not. (See the example I posted above)

Energy does not cause expansion. It's a wrong conclusion drawn from what's happening. A bullet has to hit something before any energy comes into play in expansion. It's the resistance of the object struck to the penetration of the bullet that causes expansion of a bullet. That bullet will expand more or less based on three things: 1) How the bullet is made (it's construction, what and how it's made, a bullet built to begin to expand at 2500 fps may not expand at all at 1500 fps, too fast the bullet may brake up, it may also plug up and fail to expand), 2) does the bullet have enough ft pds of energy available to it to expand, enough power left to it to expand, 3) the resistance of the object struck. A brick wall has a lot more resistance to it than a hog shoulder. So the bullet may shatter or fail to expand at all due to deformation, etc.

Thinking that energy causes expansion is a mistake. But to expand requires energy. It's not just "math, math,math" as someone said.

 

[Kleanbore]

Energy does not cause expansion.

The conversion of energy is what causes expansion.

A bullet has to hit something before any energy comes into play in expansion.

Yep. You have to exert force, and that requires energy and a collision.

That bullet will expand more or less based on three things: 1) How the bullet is made (it's construction, what and how it's made, a bullet built to begin to expand at 2500 fps may not expand at all at 1500 fps, too fast the bullet may brake up, it may also plug up and fail to expand), 2) does the bullet have enough ft pds of energy available to it to expand, enough power left to it to expand, 3) the resistance of the object struck.

Not a bad summary, but add energy.

Of course, construction in this context includes sectional density, materials and bonding, ogive, design of the expansion cavity, the shape of the jacket....

It's not just "math, math ,math" as someone said.

No. It's physics and materials science. Math just describes some quantitative factors.

 

[ATLDave]

Of course it's "math, math, math," but the real math is insanely, impossibly complex. We can make the math manageable by simplifying the model. The more simplification we have, the more likely the model is to depart from reality in some circumstances. As we add variables to the equations, then we can get widely varying results based on small differences in one or more of those variables. That's realistic (think a .22lr bullet splattering on a rib bone versus perforating the left ventricle... small changes, big difference in outcomes)... but it then defies reporting results as a single number.

 

[lysanderxiii]

The expenditure of energy is the cause of metal and flesh being deformed, period. Ergo, energy causes expansion.

Stating anything to the contrary just shows a lack of understanding of physics.

The degree of said deformation of flesh and metal are governed by many factors, but that does not negate the simple truth that energy is required. And that deformation cannot exceed some limit imposed by the striking energy.

To all those that think otherwise, please explain by what magical power a bullet change shape after striking a target?

 

[ATLDave]

To all those that think otherwise, please explain by what magical power a bullet change shape after striking a target?

It's the ghost of Lee Juras.

 

[mcb]

I like Barnes bullets they expand so pretty.


Another similar data set also from Barnes


Hornady


Swift


Correlation does not necessarily mean causation but I see no other cause of the greater deformation of the bullet as the velocity increases (and thus kinetic energy) at the time of impact.

I have said this several times and will repeat myself here. I am still struggle to see what other source of energy would cause a bullet to expand other than the kinetic energy of its motion. There is no other source of energy to do the work required to plastically deform the projectiles.