Terminal Balistics

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by msp21, Apr 17, 2008.

  1. msp21

    msp21 Member

    Messages:
    7
    Joined:
    Apr 8, 2008
    I am mauling over a custom rifle and after much research I have a question that I can not find the answer for. Can any one tell me if any real terminal ballistics are gained from going from lets say a .308 to a 300 WM? Both shoot the same diameter bullets but he 300 WM does it a little quicker and of course can loft slightly heavier bullets; but still they are the same diameter. If one was going to step up to a magnum caliber to gain terminal ballistics wouldn't one be better suited to chose a larger diameter bullet like a .338? What should person be looking at when trying to decide on a caliber...sectional density, energy, ect?
     
  2. papa45

    papa45 Well-Known Member

    Messages:
    61
    Joined:
    Feb 22, 2005
    It could take a book to answer your question. First, same diameter does not equal same terminal ballistics. Terminal ballistics usually means the effect of the bullet on the target. Energy equals mass times the square of the velocity, so in simple terms, twice the mass (weight) at the same velocity equals twice the energy. Obviously increased velocity also means increased energy. An important consideration in terminal ballistics is how the bullet behaves on impact. Some bullets expand rapidly, dissipating their energy on the target. Some bullets penetrate. Another important factor, especially to long-range shooters, is trajectory; higher velocities and higher ballistic coefficients mean flatter trajectories. I suggest you do a search on the forum for related topics. You can pick up a lot here. I'm sure lots of forum members will chime in with lots more. Welcome to the forum.
     

  3. msp21

    msp21 Member

    Messages:
    7
    Joined:
    Apr 8, 2008
    Thanks for the reply. I do understand bullets and how they react dictates energy transfer. What I am talking about is if the same bullets are used would the increase in energy alone be worth the jump to a magnum caliber over a standard caliber or would you gain much more by jumping up in bullet diameter.
     
  4. Varminator 911

    Varminator 911 Well-Known Member

    Messages:
    337
    Joined:
    Dec 7, 2007
    bigger is better

    I think most people would agree that you gain more killing power by increasing bullet diameter than by increasing velocity. A 338 bullet with the same energy as a faster 308 bullet will kill better all other things being equal. A good example might be a comparison of a 30-06 to the 35 Whelen. If loaded to the same energy level, the 35 will be a better killer especially on large animals. If going after dangerous game, I'd much rather have a 9.3x62 than a 300WM even thou the 300 would probably carry more energy. A 286 gr bullet at 2400 fps has 3658 ftlb. A 200 gr at 3000 has 3996 ftlb. I'd still take the bigger bullet against dangerous game. Now if both bullets were TSXs you'd probably be OK either way. With cup and core bullets, even the bonded kind, the advantage in my mind would swing more to the bigger slower bullet. With a non bonded standard cup and core, big advantage to the bigger slower bullet.

    Just my 2c worth
     
    Last edited: Apr 19, 2008
  5. devildoc

    devildoc Well-Known Member

    Messages:
    285
    Joined:
    Feb 10, 2006
    If that were true, wouldn't it also be true that a .45acp would be a better killer than a .243? The diameter of a bullet has an effect, but that effect would be on the impulse, how fast the energy is transferred. Alot of the myths about this are due to drawing conclusions from older poorly expanding bullets. An example of this is the myth that a .45acp is a much more lethal cartridge than the 9mm NATO, even though they are very close in muzzle energy. When you're talking about FMJ in a military context the .45 is a much more effective cartridge, but once you compare modern expanding hollowpoints the similarity of there energy potential becomes apparent.
     
  6. jwp475

    jwp475 Well-Known Member

    Messages:
    2,595
    Joined:
    Feb 4, 2005
    A 475 Liebaugh will certainly work better on large animals than a 243 despite the 243 edge in FPE... BTDT
     
  7. devildoc

    devildoc Well-Known Member

    Messages:
    285
    Joined:
    Feb 10, 2006
    I would challenge those assumptions, both the .475 linebaugh and .243 put out very similar muzzle energy(~<2000fpe) when you are using the 100gr class bullets for the .243, not to mention I'd say it's a bold statement to assume the .475 works better on big game....at what range? Within 100yds? Would that change if you chose a lighter jacketed .243 for those <100yd shots? I suspect it would.
     
    Last edited: Apr 19, 2008
  8. jwp475

    jwp475 Well-Known Member

    Messages:
    2,595
    Joined:
    Feb 4, 2005
    The 475 is about 300 FPE behind the 243 when compairing a 100 grain at 3000FPS and a 420 in the 475 at 1350. The 420 is the preferred wight for large game IMHO and experience..

    If you want to shoot large game with a 243 have at it a vary naive approach in my opinion and when penetration is short a causes a problem be sure and report it..


    One shot complete pass through and the Bull went no where less FPE than a 243, yet much better penetration and tissue damage


    [​IMG]



    The next 2 photos are of the same Elks rib cage


    This one is the exit of a 180 grain from a 300 Win with an impact velocity of approx. 2600 FPS for 2700 FPE


    [​IMG]



    This one is the exit of my 500 JRH with a 440 grain at 950 FPS for 882 FPE


    [​IMG]




    FPE doesn't look very accurate to me.....
     
    Last edited: Apr 19, 2008
  9. devildoc

    devildoc Well-Known Member

    Messages:
    285
    Joined:
    Feb 10, 2006
    What kind of bullets were you using for the 300 & 500? How bout the load on the .475? What ranges?
     
  10. jwp475

    jwp475 Well-Known Member

    Messages:
    2,595
    Joined:
    Feb 4, 2005
    I shoot Flat point hard cast in my hunting revolver exclusively... The buffalo was taken with the 500 Linebaugh with a 525grain WLFN at about 1100 FPS and rang was about 45 yards. That is 1410 FPE for the 500 with the 525 yet it has out penetrated the 475 with a 420 flat point hard cast at 1382 FPS not by much but more is more and also leave a slightly larger wound channel.

    The 300 Win was shooting a 180 grain at about 3070 FPS and the range on the Elk was 286 yards at about 1200 feet of elevation. Exball calculated velocity at that range at 2600 FPS...
     
  11. SheepShooter

    SheepShooter Member

    Messages:
    5
    Joined:
    Apr 10, 2008
    Damage to target tissue is equal to: velocity^2 * diameter^2...
    Penetration in target tissue is equal to: mass * velocity^2 / diameter^2...

    Savest way to have more damage and more penetration is to go up in velocity...

    Changing only diameter (actualy it is bullet frontal area size) will make one effect go up and the other go down...
    Changing mass will help in penetration...

    Bullet diameter/area size changes because of bullet deformation/fragmentation...
    Fragmentation means bigger area sizes...
    You get different deformation with same bullet at different velocities...
    Choose the right bullet typ for the target and (caliber) velocity...

    For every target you shoot you will have a different target medium setup...
    And the reaction of the target to the same damage can be different...
     
  12. devildoc

    devildoc Well-Known Member

    Messages:
    285
    Joined:
    Feb 10, 2006
    Well, I don't think hard cast bullets are quite applicable to what we're talking about, I guess they are used for hunting by some and in some cases where max penetration on extremely thick skinned game they may be a good choice. I guess your offerings bring up other questions; 1) is penetration a good indicator of trauma? 2) Is exit wound a good indicator of trauma?

    Though we tend to disagree on alot of points about terminal ballistics, these discussions have illustrated why terminal ballistics is such a widely debated topic. There are no easy answers and being as it covers such a wide variety of conditions one has to tailor his tool kit to the conditions he is expecting to encounter. Each condition has it's own set of limiting factors and if a shooter doesn't address those limiting factors he's liable to recieve poor performance.

    Take for instance two conditions, one being your buffalo hunt and one being a shot on a prairie dog. For the sake of simplicity lets assume that both shots will be taken at the same range, and roughly the same anatomical shot placement. For my own purposes lets say that shot placement is not Ideal and punches through the exteme bases of the lungs and halfway between the lateral midline and the spine.

    Obviously our limiting factors for each condition are opposite, the buffalo being penetration and the prairie dog being expansion/quick energy dump. To complicate matters the prairie dog takes a whole lot less volume of trauma to make a clean DRT kill than the Buffalo, and we don't really give a rats posterior how much meat damage we do to the prairie dog.

    (to be continued, my brother just got home 15mins ago from the sandbox)
     
  13. Varminator 911

    Varminator 911 Well-Known Member

    Messages:
    337
    Joined:
    Dec 7, 2007
    What works in Africa: Big bullets

    I'm with jwp on this one. What has worked in Africa on the worlds toughtest game for the last 100 yrs is big bullets not too fast. True we have better bullets now for the high velocity loads, but I think bigger is still better on large, hard to kill game. I'm not talking deer. You can kill them with anything and they are suseptible to high speed bullets that fragment.

    On big tough to kill game like Cape Buffalo, big bullets simply work better. They eat little fragmenting bullets for lunch. The 9.3x62 has has been the 30-06 of Africa for a good reason. It's a dependable killer of tough animals that can be put in an easy to carry and shoot package. A 286 gr bullet such as the TSX at 2400fps from a 9.3x62 will cleanly kill anything short of an elephant. If you'd rather have a 257 Weatherby fine, but not me. The bigger bullet is way more dependable even if the 257 is shooting a TSX.
     
  14. jwp475

    jwp475 Well-Known Member

    Messages:
    2,595
    Joined:
    Feb 4, 2005
    The handgun rounds demonstrate the inaccuracy of FPE as the sole determining factor...


    With the Prairie dog the extreme amount of Hydraulic Pressure causes the tissue to expand past it's elastic limits and rips his body apart. The same will happen on a Moose, but the wound would be shallow and not deep enough for the lack of momentum.. A high amount of momentum is not needed for the Prairie Dog, High Hydraulic pressure created Quickly is preferred..


    You are exactly correct Terminal ballistics is a combination of different dynamics that must be balance for the most effective results..