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Thread: An itheresting study on big bore penetration

  1. #1
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    Default An itheresting study on big bore penetration

    Here's an interesting study by Randy Garrett (Garrett Cartridges) on penetration in the .458 dia cartridges. His findings are interesting to say the least. Sorry if this has already been posted & I missed it.

    http://www.garrettcartridges.com/Penetration.htm

    The conclusions I draw from them are that the only thing speeds above 1800fps will gain you is a flatter traectory.
    I'm just starting to play with a guide gun again in 450 & looking forward to load development.
    Vance in AK.

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    I have read this study and the one done on handguns (which I can't find my link for), and find the results interesting. However, I think they should be taken with a grain of salt. Mostly because they rely on the idea that all we have to penetrate is meat. What happens when A bone is hit, this might change the results considerably. Most often the most important parts of an animal are behind bones, and having the energy needed to break them and keep going is important, sadly I can think of no good bone substitute. Use of real bones would be good, but hitting the bone the same in each test and variations between bones would make such an experiment difficult.

    Also, we need to think of the size of the wound channel. If a lower velocity (energy) bullet is to penetrate further it must do so by using less of its energy per inch of penetration. So it would stand to reason that it does so by creating a narrower wound channel.

    I am not arguing with the results of this study, but think they do not show the whole picture.

  3. #3

    Default Penetration

    Even a solid projectile will expand if it strikes a surface at elevated velocities; This expansion is detremental to penetration.
    As he said the bullet driven at 1500 fps penetrated 6 feet. How many North American animals are 6 feet from rib to rib (including ribs)? You don't really need six feet of penetration usually 3 would be more than necessary.
    But the increase in velocity does increase hydrstatic shock, blunt force trauma, and bullet expansion as well as recoil.
    The more power a rifle produces the more it needs to weigh to not injure on both ends. Not to mention bullet construction; Just bullet construction could be a 10 page argument on this forum.
    " Americans will never need the 2nd Amendment, until the government tries to take it away."

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  4. #4

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    Hydrostatic shock does not exist. Hydo-Power generated using water pressure: Static - Not moving or changing, fixed position. The concept and term hydrostatic shock is an oxymoron.

    Read this:

    http://www.rathcoombe.net/sci-tech/b...ics/myths.html
    A GUN WRITER NEEDS:
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  5. #5

    Default Great read

    Quote Originally Posted by beartooth View Post
    Hydrostatic shock does not exist. Hydo-Power generated using water pressure: Static - Not moving or changing, fixed position. The concept and term hydrostatic shock is an oxymoron.

    Read this:

    http://www.rathcoombe.net/sci-tech/b...ics/myths.html
    But if hydraulic shock does not exist then the bullet can only destroy what it touches, connects with, or cuts. And wound channels 5-6 inches in diameter don't exist. I've seen these myself, so the bullet imparts a hydraulic shock causeing hyper extended wound channel; As well as bullets tearing through lung tissue turn the heart into jello.
    Call it what you want it exists !! LoL
    " Americans will never need the 2nd Amendment, until the government tries to take it away."

    On the road of life..... Pot holes keep things interesting !

  6. #6

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    Physics is physics. An object in motion tends to stay in motion. It akes force to put an object in motion and it takes force to slow and/or stop an object.

    If you fire a 500 gr, .458 cal bullet at 30 degrees of trajetory @ 1500 fps, and fire another 500 gr, 458 cal bullet at the same trajectory @ 3000 fps, which do you suppose will go farther? They are both "penetrating" the medium of atmosphere.

    Velocity and mass produce momentum and energy. a 500 gr, .458 cal bullet with a velocity of 3000 fps has a KE of 9992 ft-lbs and a momentum of 214 lb-ft. At a velocity of 1500 fps the KE is 2498 ft-lbs and 107 lb-ft.

    It takes a certain amount of force to put an object in motion at a particular velocity and it takes an equal amount of force to stop it. Period. More velocity = more force, period.

    When a bullet moves through the atmosphere, it encounters resistance (friction - force) from air molecules. Some bullets overcome that resistance bette than others based on their shape and surface properties (BC).

    Flesh, like air is a medium that offers resistance to bullets. A bullet that maintains its shape while penetrating any particular medium will penetrate farther with higher velocity and force.

    Yep, there is a lot of info missing from this articel, like what happens to these bullets when they meet the medium?

  7. #7

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    Please read the article and you will have a better understanding.
    "Hydro" meaning "liquid"
    "static" meaning "no movement"
    Kinda self-canceling isn't it?

    Some people get very annoyed when their claims are proven wrong by scientific testing. If there was any validity to the claims of "hydrostatic shock", whatever that term is supposed to mean, then ask yourself why a block of gelatin does not simply blow apart into little pieces when the bullet hits it?

    The correct term would be "hydrodynamic" meaning "fluid in motion".
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  8. #8

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    Energy is ok and obviously needed but one needs to think about momentum. If one looks at "energy", a 0.224" 60gr bullet launched from the 5.6x63 at 3990fps shows 2122 ftlbs of ME yet a 500gr FN launched from the .45-70 is moving at just 1350fps at 100yds delivering 2024 ftlbs of energy, which one is more effective at taking a 1200 pound moose at 100yds?

    The two most important concerns are "size and depth of the permanent wound channel" and "available bullet momentum". The fast little 60gr bullet isn't going to penetrate because it's got very little momentum despite the impressive looking energy number. On the other hand, the slow un-sexy 500gr cast lead FN bullet from the .45-70 has enough momentum to not only penetrate completely through the boiler room of that moose but both shoulder bones as well if you so desire. If I take a volkwagon bug and move that little car at 1,000 miles per hour and hit a brick house with it, the little car will come apart into a thousand little parts and the house will have major damage. Now you let me move a train engine at 60 miles per hour and hit that house, the train engine will go slap through that house out the other side and continue on for a while.

    Thus, "momentum" and not "energy" is what to look at. On the same note, bullet design is all important because a 0.458" Postell style bullet is not going to create as a large a permanent wound channel as half-radius RN of the same size and weight. True, the Postell will show deeper penetration but at the cost of giving up permanent wound channel diameter and tissue tearing.

    Compare this to the wound channel difference you would see in a body stabbed with a 6" long razor sharp dagger - straight in, straight out - verses the wound channel that would be produced in the same body with the same mechanism by a piece of 1" diameter steel rod saw-cut square on the end. While the dagger will leave a nice pretty smooth cut, the piece of steel bar is going to rip & tear everything it comes in contact with; the resultant hole left behind when it's pulled back out is going to be quite nasty.

    Now I like speed with my Weatherby's but I know that speed does not make up for momentum and bullet construction. If I had to choose I would go slower and bigger. Now Yes I said that.
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  9. #9
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    Quote Originally Posted by MontanaRifleman View Post
    Physics is physics. An object in motion tends to stay in motion. It akes force to put an object in motion and it takes force to slow and/or stop an object.

    If you fire a 500 gr, .458 cal bullet at 30 degrees of trajetory @ 1500 fps, and fire another 500 gr, 458 cal bullet at the same trajectory @ 3000 fps, which do you suppose will go farther? They are both "penetrating" the medium of atmosphere.

    Velocity and mass produce momentum and energy. a 500 gr, .458 cal bullet with a velocity of 3000 fps has a KE of 9992 ft-lbs and a momentum of 214 lb-ft. At a velocity of 1500 fps the KE is 2498 ft-lbs and 107 lb-ft.

    It takes a certain amount of force to put an object in motion at a particular velocity and it takes an equal amount of force to stop it. Period. More velocity = more force, period.

    When a bullet moves through the atmosphere, it encounters resistance (friction - force) from air molecules. Some bullets overcome that resistance bette than others based on their shape and surface properties (BC).

    Flesh, like air is a medium that offers resistance to bullets. A bullet that maintains its shape while penetrating any particular medium will penetrate farther with higher velocity and force.

    Yep, there is a lot of info missing from this articel, like what happens to these bullets when they meet the medium?
    I'll pick on you Montana since I know you don't mind and I'm bored. What you say here is true...mostly. I'm not sure if energy (M/2*V*V)has to do with penetration or if it is really just momentum (M*V) [I'm a momentum guy]but either way velocity ups the number. Penetration would then in either case be a product of Mass, Velocity and Sectional Density (w/d*d). Or we could just come up with a figure or penetration index based on M*V/d * f (some form factor because shape does matter). Smaller diameter of same weight and velocity will penetrate deeper. All this is only true if the shape never changes as it penetrates throught the medium. It doesn't change shape in air but likely will change through animal tissue and bones. Even solids if impact velocity is fastest enough, will deform. I think what Garrett is giving is the max velocity for certain types of projectiles without deformation and limiting penetration. But you're right it is difficult the bend the laws of Physics very far.
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  10. #10

    Default AIR

    Quote Originally Posted by beartooth View Post
    Please read the article and you will have a better understanding.
    "Hydro" meaning "liquid"
    "static" meaning "no movement"
    Kinda self-canceling isn't it?

    Some people get very annoyed when their claims are proven wrong by scientific testing. If there was any validity to the claims of "hydrostatic shock", whatever that term is supposed to mean, then ask yourself why a block of gelatin does not simply blow apart into little pieces when the bullet hits it?

    The correct term would be "hydrodynamic" meaning "fluid in motion".
    Air is nothing more than a super thin liquid. Even it's consistency changes; That's called humidity and oxygen. That's why jets climb to 30-50-000 feet ; To get away from air drag(friction if you will), air is thinner the higher you go until it's non existant; That's called space.

    So call it spagetti if you want to; when a bullet at extreme speeds hit a fluid filled mass the mass will emit a hydraulic shock wave.

    http://www.youtube.com/watch?v=2-rHJnuXilg&NR=1
    " Americans will never need the 2nd Amendment, until the government tries to take it away."

    On the road of life..... Pot holes keep things interesting !

  11. #11

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    Murphy, I don't complelty understand the relationship between energy and force, but I am also a momentum kind of guy, thinking velocity has a more proportional effect on penetration. I quite frankly I dont understand the concept pf squaring velocity in determining KE.

    But anyhow, all other things being equal an object moving a 2X velocity will penetrate farther than an object moving at X velocity. Aint no way around it.

  12. #12

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    Quote Originally Posted by MontanaRifleman View Post
    Murphy, I don't complelty understand the relationship between energy and force, but I am also a momentum kind of guy, thinking velocity has a more proportional effect on penetration. I quite frankly I dont understand the concept pf squaring velocity in determining KE.

    But anyhow, all other things being equal an object moving a 2X velocity will penetrate farther than an object moving at X velocity. Aint no way around it.
    ONLY, If the additional velocity doesn't cause bullet deformation resulting in the bullet to have a larger frontal area, slowing its penetration through the medium.
    " Americans will never need the 2nd Amendment, until the government tries to take it away."

    On the road of life..... Pot holes keep things interesting !

  13. #13

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    Quote Originally Posted by brav01 View Post
    Air is nothing more than a super thin liquid. Even it's consistency changes; That's called humidity and oxygen. That's why jets climb to 30-50-000 feet ; To get away from air drag(friction if you will), air is thinner the higher you go until it's non existant; That's called space.

    So call it spagetti if you want to; when a bullet at extreme speeds hit a fluid filled mass the mass will emit a hydraulic shock wave.

    http://www.youtube.com/watch?v=2-rHJnuXilg&NR=1
    Hydraulic shock is true, my point was Hydrostatic shock is not a correct term. And the extreme speeds hitting fluid filled mass will not emit but produce a hydrodynamic flow and not until it hits resistance in the track of the flow is there any thing even a kin to shock of any kind. You and I are on the same page when it comes to momentum.

    I am getting a headache, I think I will let you guys sort this one out.
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  14. #14

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    Quote Originally Posted by brav01 View Post
    ONLY, If the additional velocity doesn't cause bullet deformation resulting in the bullet to have a larger frontal area, slowing its penetration through the medium.
    Exactly, that's what "all other things being equal" means.

    Most bullets are designed to deform to cause damage.

  15. #15

    Default BUT

    Quote Originally Posted by MontanaRifleman View Post
    Exactly, that's what "all other things being equal" means.

    Most bullets are designed to deform to cause damage.
    YEP; Even solids will compact if the velocity gets high enough. That's why we've got regular bullets, premium bullets, solid copper bullets, solid steel bullets, titanium bullets and uranium bullets. Use what is neccessacary for your task at hand.

    These lead/copper bullets probably became the size of 50 cent pieces at the higher velocities quoted, sheding their velocity.
    " Americans will never need the 2nd Amendment, until the government tries to take it away."

    On the road of life..... Pot holes keep things interesting !

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    Quote Originally Posted by beartooth View Post
    Hydrostatic shock does not exist. Hydo-Power generated using water pressure: Static - Not moving or changing, fixed position. The concept and term hydrostatic shock is an oxymoron.

    Read this:

    http://www.rathcoombe.net/sci-tech/b...ics/myths.html
    I could be wrong, sure wouldn't be the first time nor last, but I think the term hydrostatic shock came into everyone's vocabulary when Robert Strange McNamara and his whizz kids decided the 5.56X45 was more lethal than the 7.62X54 and needed a fancy term to explain how a small pill could kill an individual by hitting them in the leg and sending a “killing” shock wave to his heart/brain. Colt Arms benefited from the term big time.

  17. #17

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    Quote Originally Posted by JoeJ View Post
    I could be wrong, sure wouldn't be the first time nor last, but I think the term hydrostatic shock came into everyone's vocabulary when Robert Strange McNamara and his whizz kids decided the 5.56X45 was more lethal than the 7.62X54 and needed a fancy term to explain how a small pill could kill an individual by hitting them in the leg and sending a “killing” shock wave to his heart/brain. Colt Arms benefited from the term big time.
    Yes, you are right, science applied to conjecture, mix with myth and stirred with emotion, some how becomes truth to many and after a while of saying it and applying it as though it is fact, it is codified into our mind set and we swear it is the truth.
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    Quote Originally Posted by MontanaRifleman View Post
    Murphy, I don't complelty understand the relationship between energy and force, but I am also a momentum kind of guy, thinking velocity has a more proportional effect on penetration. I quite frankly I dont understand the concept pf squaring velocity in determining KE.

    But anyhow, all other things being equal an object moving a 2X velocity will penetrate farther than an object moving at X velocity. Aint no way around it.
    I didn't write the equation but that's what it is. Both are correct Energy and Momentum. And before you go off the deep end I can tell you it is without the slighest shadow of doubt that the momentum is what pushes the bullet through the stuff. Energy works against penetration with hunting bullets because it causes more rapid expansion, deformation or what ever we call it. Bullets are designed to cause damage and will and shape is a major factor in this damaging potential.

    Penetration: an object at two x V will penetrate 2X.? Not even close. AN object with 2x Momentum will, IF same diameter.

    Velocity times Mass is momentum. Mass in motion. What is your definition of force? What is your deifnition of energy?

    Your thinking isn't supported in science, if so an 8 grain projectile at 18,000 fps would do a lot of damage. Diameter and weight do damage. An 400,000 ton ship at 1/16th mph will take out a concrete pier for over 50 yards. I watched it. This is fun on a cold winter night. Hey is it cold in Montana?
    Is there nothing so sacred on this earth that you aren't willing to kill or die for?



  19. #19
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    Default You are both correct!

    MontanaRifleman covered his bases very well with his "all other things being equal" statement. If the only variable is velocity and you double it then the momentum is also doubled.
    --->An 8 grain projectile at 18,000 fps will have les energy than will an 8 grain projectile at 36,000 fps. All other things are equal and speed/velocity is the only change.

    Murphy is also correct that mass effects momentum. If this time mass is the only variable when you double the mass at any given velocity the momentum of the object will also double.
    --->A 400,000 ton ship at 1/16th mph will do less damage, has less energy, than an 800,000 ton ship at 1/16th mph.

    The two (mass and velocity) are forever linked to momentum; it takes both together to make momentum.

    The thing that muddies the waters is the shape of the mass involved, and how that shape may be altered on impact. We know the amount of energy it has when exiting the muzzle, but from there on how much of that energy is used for what is dictated by the shape in the air and the shape after impact.

    What the Garrett article points out is interesting indeed, but I want to know the “why” before I alter my habits and beliefs. Why is there less penetration when we know there is more energy/momentum? What happened to the energy that must have gone into the target, and is what ever happened to it desirable or undesirable for our goal? I suspect that energy is turning into shock waves on impact, but even if I’m correct I don’t know if that’s good or bad. I would like to see some serious studying of this so we can understand what is going on with this phenomenon.

    Andy

  20. #20

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    The variables of energy/momentum and their Terminal results, I believer are beyond us to capture them in any final definitive way and if I am wrong, like ADfields I would like to know.
    A GUN WRITER NEEDS:
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