Quantcast

Momentum vs Kinetic Energy visualized, no mention of lethality

Discussion in 'General Gun Discussions' started by mcb, Nov 22, 2019.

  1. 35 Whelen

    35 Whelen Member

    Joined:
    Feb 10, 2008
    Messages:
    3,076
    Location:
    North Texas
    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??

    Recovered%20bullets_zpsc9ey0zbr.jpg

    Sierra140gr.jpg

    PA200001.jpg

    Elkbullet1smallest.jpg

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

    429244-2_zps9vrmnkgc.jpg

    357%20Carbine%20bullet_zpso8w7xbdx.jpg

    Bullet%20from%20Spike_zpsn1x49cvb.jpg

    bullet_zpsd62d630c.jpg

    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
     
    Last edited: Dec 1, 2019
  2. d2wing

    d2wing Member

    Joined:
    Nov 10, 2008
    Messages:
    3,674
    Nice pictures. Merry Christmas.
     
  3. mcb

    mcb Member

    Joined:
    Feb 19, 2008
    Messages:
    2,128
    Location:
    North Alabama
    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.
     
    Last edited: Dec 1, 2019
  4. d2wing

    d2wing Member

    Joined:
    Nov 10, 2008
    Messages:
    3,674
    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.
     
  5. Jim Watson

    Jim Watson Member

    Joined:
    Dec 24, 2002
    Messages:
    25,946
    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, killing a deer was a lifetime accomplishment. Turkey? Forget about it.
    Now it is more like going to the grocery store.
     
    d2wing and 35 Whelen like this.
  6. 94045

    94045 Member

    Joined:
    Oct 28, 2018
    Messages:
    1,093
    Don't blame math for poor mathematicians.
    Reality is defined by math.
    But first you have to ask the right question.
     
  7. Kleanbore

    Kleanbore Moderator Staff Member

    Joined:
    Aug 13, 2008
    Messages:
    9,143
    No. You missed the point entirely.

    No, not everything .
     
  8. tipoc

    tipoc Member

    Joined:
    Mar 9, 2006
    Messages:
    3,317
    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.
     
    Last edited: Dec 2, 2019
  9. 35 Whelen

    35 Whelen Member

    Joined:
    Feb 10, 2008
    Messages:
    3,076
    Location:
    North Texas
    Then.....

    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)

    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.". :thumbdown:

    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
     
  10. tipoc

    tipoc Member

    Joined:
    Mar 9, 2006
    Messages:
    3,317
    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;)
     
  11. Kleanbore

    Kleanbore Moderator Staff Member

    Joined:
    Aug 13, 2008
    Messages:
    9,143
    Nope!

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

    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.

    Has someone tried that?
     
  12. tipoc

    tipoc Member

    Joined:
    Mar 9, 2006
    Messages:
    3,317
    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.
     
  13. Kleanbore

    Kleanbore Moderator Staff Member

    Joined:
    Aug 13, 2008
    Messages:
    9,143
    The conversion of energy is what causes expansion.

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

    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....

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

    ATLDave Member

    Joined:
    Aug 30, 2011
    Messages:
    8,249
    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.
     
  15. lysanderxiii

    lysanderxiii Member

    Joined:
    Mar 21, 2015
    Messages:
    1,610
    Location:
    North Carolina
    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?
     
  16. ATLDave

    ATLDave Member

    Joined:
    Aug 30, 2011
    Messages:
    8,249
    It's the ghost of Lee Juras.
     
  17. mcb

    mcb Member

    Joined:
    Feb 19, 2008
    Messages:
    2,128
    Location:
    North Alabama
    I like Barnes bullets they expand so pretty.
    hgbullett_071207a.jpg

    Another similar data set also from Barnes
    TSXvsLRX1_zpsee2f4574.jpg

    Hornady
    tic.fixphotobucket.com%2Falbums%252Ftt183%252Fmenarefrommars%252F130grGMXComparison100to500yards.jpg

    Swift
    SwiftAframe+expansion+velocities.gif

    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.
     
    Last edited: Dec 2, 2019
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice