Energy vs. Energy Transfer

Discussion in 'Elk Hunting' started by hawk4974, Apr 30, 2014.

  1. hawk4974

    hawk4974 Well-Known Member

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    With all of the talk around "what is the best caliber for....." why is it that you don't hear much about energy transfer? For example, hitting an elk with a 250gr .338 will transfer it's kinetic energy better than a 150 gr 7mm Mag assuming the same energy down range. The best way I've heard energy transfer described is would you rather get hit with a fast pebble or a slow brick. Maybe the theory is implied but to a newbie it would seem easier to explain this as opposed to BC, velocity, etc.

    Thoughts, theories, and postulations please....
     
  2. gohring3006

    gohring3006 Well-Known Member

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    I think that its not talked about much because the energy that is needed is produced easily with most rifle cartridges and bullet design has alot to do with how energy is transfered you can dump all of your available energy in the animal with certain bullets or you can have a bullet zip right through the animal and dump its energy in the hill behind it so its varied by bullet design,mass and velocity. So for most north American big game a small well designed bullet cookin at 3000fps shot with precision,emphasis on precision.is a better choice. that's the fast pebble, then for dangerous game the slow brick is better I want a big heavy slug dumping all of its energy in a charging grizzly or cape buffalo at 12yrds instead of zipping through it like a needle and not stopping so I think you would hear more about energy transfer in Africa and in grizzly country
     

  3. marioq

    marioq Well-Known Member

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    The other thing to think about, is that energy transfer is not just relying on muzzle velocity and weight of the bullet. The fragmentation of the bullet and how that energy is distributed in the soft tissues accounts for the energy transfer. The bullet zipping through idea is a prime example of that. The energy is spent piercing the skin any bone but anything that is left over with an intact bullet will cause loss of energy. I think this number is very hard to calculate exactly. But an idea if transfer is likely more helpful.
     
  4. Topgun 30-06

    Topgun 30-06 Well-Known Member

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    So are you saying you'd rather see your bullet fragment, rather than stay together inside the animal as it expands to 2x-3x it's diameter and drops it's energy? If you are, I'm not in your camp theory!
     
  5. cohunter14

    cohunter14 Well-Known Member

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    Yeah, there is no real way to calculate KE because you don't ever know exactly what a bullet will do. Bullets all react differently based on what they are hitting, what range they are at, and what speed they are traveling at that point. KE itself isn't all that important, although it could seem that way. Some people prefer to have a bullet react like a Barnes, where it will retain all it's weight and penetrate deeply, most times even creating two holes (one in, one out), whereas some prefer a Berger that dumps a lot of it's energy upon contact and not exiting very frequently. Both methods work very well and you could debate all day on which is better.

    However, the one thing that really can't be debated is that a larger diameter bullet should typically do better, assuming everything else is the same at impact. A larger hole will never hurt you :D. So whether you are shooting a Barnes, a Berger, or whatever else is out there, a .338 will do more damage than a .30, etc.
     
  6. marioq

    marioq Well-Known Member

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    Amen brother!!!
     
  7. marioq

    marioq Well-Known Member

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    No not saying that. Explaining that the question is hard to answer exactly. There are more factors than weight and bullet velocity. Composition matters, materials have an innate property that must be factored into the calculation, though this in nominal in some cases. The question was not asked what do I prefer. It was about energy transfer.
     
  8. FearNoWind

    FearNoWind Well-Known Member

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    "Knock down" power relies on the transfer of kinetic energy to the target AND its affect of vital organs. The broader the wound channel, the greater impact the transfer of kinetic energy will have on vital organ function. For example, when a bullet strikes a bullet proof vest it's kinetic energy is (hopefully) transferred over a broad surface. While the bullet may not penetrate, the energy is still transferred to the individual wearing the vest and can, if there's enough of it, cause internal organ damage.
    The following are, admittedly, generalizations. But they can help provide an understanding of Energy vs Energy Transfer.
    Small bullets at high velocity carry a lot of kinetic energy but their cross sectional density isn't sufficient to prevent them from traveling through the target without transfering that energy to the target. If a small bullets happens to strike a vital organ it can be effective. Generally, however, it is a poor choice for anything other than ground squirrels or similar game. Large caliber bullets, carrying less kinetic energy, have a broader cross section density so they tend to remain in the target and therefore transfer more of their energy (albeit less total energy than the smaller bullet) to the target. That makes them more suitable for hunting large game.
    That said, the transfer of energy is not sufficient in and of itself. Unless that energy is transferred to a vital organ (artery, heart, etc.) the targeted animal will remain active until sufficient bleed out occurs or until the shock of it's transferred energy has enough cumulative impact on vital organs to render it unable to function.
     
  9. gohring3006

    gohring3006 Well-Known Member

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    energy transfer is dictated by bullet design velocity and mass.if I take a 308cal. 180gr. Bullet and fire it at 2700 fps and take that same bullet and fire it at 3300fps it energy transfer will be different at different velocities read about John noseler experience on a moose and why he invented the partition. Bullet weight retention and velocity will dictate transfer
     
  10. hawk4974

    hawk4974 Well-Known Member

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    I would concur!!
     
  11. hawk4974

    hawk4974 Well-Known Member

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    Now there's a mouthful of 5 dollar words! Well said!
     
  12. hawk4974

    hawk4974 Well-Known Member

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    I need to find this article. Sounds interesting how he came up with it. I do agree with FearNoWind regarding sectional density though. It would be neat to study the same grain weight bullet traveling at the same speed yet with a different diameter. For instance, a 200 gr .308 and a 200 gr .338 or even a 7mm vs .308. If all are equal except for diameter, it would stand to reason that the larger the diameter the larger the wound cavity one would think.
     
  13. gohring3006

    gohring3006 Well-Known Member

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    yes I agree but tearing a bigger hole in something has nothing to do with energy transfer I think a 338lapua full metal jacket will put a 338 hole in a animal an keep going some of its energy is transfered in the target a 30 cal partition will dumps all of its energy with out exiting two different energy transfers
     
  14. hawk4974

    hawk4974 Well-Known Member

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    It has to have SOMETHING to do with energy transfer because it has a larger area for resistance. Again, if bullet design, grain weight, and velocity are equal between calibers, the larger the surface area of the bullet the quicker the transfer of it's energy. My brother in law could probably help me with this experiment. We obviously couldn't compare a 250gr .338 Lapua FMJ to a 110gr .308 hollow point. It would probably easier to test if you used a 30-06 and a 338-06 to compare transfer. That way one might be able to attain the same velocities using the same type of bullet and grain weight. Hypothetically a 200 Gr Partition in .308 and .338. You's have to chrono both rounds to make sure the velocities are the same on then hit some gel with it to view penetration depth and cavity size.