Terminal Energy Required to Kill Game

Discussion in 'Long Range Hunting & Shooting' started by cronhelm, Jul 19, 2001.

  1. cronhelm

    cronhelm Well-Known Member

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    Anyone have any thoughts on the amount of terminal energy required to cleanly kill game?

    I looked in a hunter-ed book and it lists the following as suggested minimums.

    Deer, Antelope, Sheep 900 ft/lb
    Elk, Small Bear 1500 ft/lb
    Moose, Large Bear 2100 ft/lb

    My ballistic computer shows that a 300gr MK out of a .338 Mag will have 744 ft/lb at 1900 yds. Does anyone really think that a 300gr bullet travelling at 1050 fps wouldn't cleanly kill a White Tail or a Mule Deer with the proper point of impact?

    (Note: I am at 4000 ft altitude so the speed of sound is approx 1050 fps)

    This may be a touchy subject but as a newby to long-range hunting I have to ask these questions BEFORE I end up wounding an animal in the field.

    Peter Cronhelm
     
  2. Darryl Cassel

    Darryl Cassel Well-Known Member

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    Hello Peter

    If your just talking about a standard case such as the 338 win. Mag. it would be hard to start out a 300 Gr bullet with enough velocity and retained energy to do what we do with a large wildcat such as the 338/378 Weatherby IMP or the 338/416 Rigby IMP.

    If you run the ballistics on your computer, start the 338---300 gr out at 3250 and then run it 3310 (Which I have done with mine) and you will see a full 180 degree turn in ballistic numbers.

    When you have a case the size of the 416 Imp and shoot 122 Grs of powder down a 37" barrel it's a whole new ball game.

    You can't compare a 338 Win mag to what we shoot.

    My Oehler Balistics program shows that there are 3104 FP left at 1000 yards and 1197 FP at 2000 yds which is plenty of energy especially since I ran it at 3250 and not the 3310 that I can run the bullet.

    I'm not sure if you were just refering to any 338 or just the 338 Win mag.

    Anyway, for the 338 Win mag. the 300 gr bullet may not be the one to use.
    In our big boys, it is.

    Peter, just read your other post and you did mention the 338 Win Mag. Factory rifle. If it has the 10 twist it will stabilize the 300 gr bullet. The 338 Win mag is a good cartridge for shorter ranges and has killed many deer, elk and Bear.
    My 338/416 IMP has a 10 twist and does fine.
    keep your ranges shorter and you will do fine with the 338 even with a 250 or 300 gr bullet.

    Later
    Darryl Cassel

    [ 07-19-2001: Message edited by: Darryl Cassel ]
     

  3. cronhelm

    cronhelm Well-Known Member

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    Darryl,

    I realize that the standard .338 Mag is no match for your big wildcats at very long range. However it is all that I have access to so I am going to have to make do.

    I would like to be able to cleanly kill game out to about 1500 to 1600 yds.

    As far as the numbers go, I punched the data into my ballistics computer, right out of the loading manual, and what it gave me was:

    1900yds Vely 1050fps(transonic) Energy 744 ft/lbs

    Keep in mind I am at 4000 ft altitude so the air is a lot thinner up here and we can get a lot more range out of standard cartridges than can be done at sea-level. I am shooting my .243 at 1500 - 1700 yds regularily and expect to break 2000yds soon.

    Anyways, my question really was do you think that 744 ft/lbs from a 300gr .338 bullet is enough to kill a deer or anything else for that matter. Keeping in mind that the Hunter-Ed book suggests 900 ft/lbs as a minimum?

    From what I have read in your's and others' posts, even a slow moving bullet can cause a huge wound if it tumbles which these big MK bullets tend to do. Therefore retained energy is less important than shot placement and a big bullet.

    Peter Cronhelm
     
  4. Darryl Cassel

    Darryl Cassel Well-Known Member

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    Peter

    The FP is enough to kill. The reason I say this is, My friends and I used to use handguns to hunt deer with. They were 357 mags, 41 Mags and 44 mags. Shots were made at anywhere from 50 yds to a tad over 100 Yds. Just check the ballistics and energy of the normal loads in an 8" pistol using the above mentioned calibers.
    You will be surprised how low they are.

    We killed a lot of deer with those handguns. One of my friends killed 11 buck in 11 years with his 357 Mag. If I remember correctly, his longest kill was 80 Yards.

    If you compare FP of energy at close range to FPs of energy at longer range and they are close to the same, you can make a very good comparison to killing power.
    The yardage in between don't mean a heck of a lot. It just so happens that, your 338 mag with 750 FPs of energy at the yards you ran ballistics on, has a lot more energy then the 357 Mag pistol does at the muzzle.

    One question, was wondering what kind of a rangefinder do you fellows use there in Alberta?
    We hunt at 7500 to 8000 ft in Colorado and I have seen how flat the trajectory is. Have never tried a straight 243 at 2000 yards YET. I have shot mine out to 1450 in PA.

    Good Luck
    Darryl Cassel
     
  5. Dave King

    Dave King Well-Known Member

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    Peter

    I see you posted at 10:43 AM in the "How Far Out Will This Rifle Perform" thread. That post pretty much answers this question as I read it.

    I'm not sure where these "standards" remaining energy values come from but I don't generally worry about them too much. Shot placement is far more important than energy (dangerous game not included).
     
  6. cronhelm

    cronhelm Well-Known Member

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    Darryl,

    You make an excellent point about the handgun energies that can obviously kill cleanly. I will look up some of those energies and see how they compare.

    It is interesting that you ask about range-finding. Dave King and I have been working on a "revolutionary" new system of GPS ranging combined with a ballistics computer for a completely integrated ranging system. I have to write the instructions today and then we will be making it available exclusively to the members of this message board to test.

    My .243 is not exactly a "straight .243". I have a fast twist, match barrel that allows me to launch moly coated, Berger 95gr VLD's at just under 3300fps. At my altitude this bullet will stay supersonic to approximately 1850 - 1900yds depending on other factors.

    I have made a hit at 1890yds already and that was with the scope not being properly setup. I had to aim "by guess and by god" to get onto the target. I have since had the scope mount fixed and should be able to go all the way to 2000yds once I find a place to set up a target and find a windless day.

    I am using the lids from 55gal oil drums (24" metal circles) as targets. To see a short story and pictures of my first attempt go to:
    http://www.nucleus.com/~cronhelm/index.html

    and click on the "Shooting at a Mile" link.

    The .243 is a good tool to practice ultra-long-range shooting but it will never carry enough downrange energy to kill anything bigger than a coyote. I did a rough estimation that at 1900yds, the 95gr VLD has approximately the energy of a .380 handgun which is not exactly a lot.

    Peter Cronhelm
     
  7. Roadrunner

    Roadrunner Well-Known Member

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    Peter,

    Remember that you can only really accurately shoot a rifle bullet out until it drops below the speed of sound. As it's dropping through the sound barrier, it becomes somewhat unstable and therefore less predictable. Groups shot when the bullet goes sub-sonic have a much larger MOA then groups shot while the bullet is still supersonic. There are many different factors that affect when a particular bullet load will go sub-sonic: altitude, air temp, ammunition temp, humidity ect. So the exact range at which this would happen on any given day is challenging to predict. But as far as any humane hunting goes, at extreme ranges you always want to ensure that your bullet stays super-sonic.

    Whenever you hear about the military shooting a fifty cal at say 3000 yrds, it's that they're probably shooting at vehicles and MOA accuracy doesn't matter as much with such large targets; esp when you're shooting many rounds (such as from a machine gun).

    Just my .02

    RR
     
  8. Warren Jensen

    Warren Jensen Well-Known Member

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    Roadrunner,

    The reason accuracy degrades in most bullets as they pass through transonic is that in general, most bullets are overspinning at that point in their flight. If the axial drag and the horizontal drag of a bullet is balanced from the muzzle then this overspinning (sometimes erroneously called overstabilized) does not occur. When a bullet is spinning faster than necessary to keep it pointed nose forward it starts to precess and yaw. The nose is a little high and to the right(for right hand twists) and is drawing little circles in the air. The greater the spin over what is necessary the greater the precession and yaw. Most bullets have axial drag numbers that are much less than their horizontal drag and, therefore, the spin rate relative to what is necessary is always increasing. This means that when they get some 1000+ yds. downrange and are approaching transonic their precession and yaw is much pronounced. During transonic passage the shock waves are collapsing directly around the bullet. When a bullet is overspinning, has pronounced precession and yaw, and enters transonic the collapsing shock waves exacerbates the condition leading to much greater inaccuracies and even total destabilization. If a bullet's flight, and drag numbers are balanced, the Balanced Flight Theory, it will be pointing directly into the oncoming air and can passage the transonic region quite accurately.

    On a slightly different subject, energy is not a good quantifier of lethality. Any comparison of energy completely ignores the expansion and penetration characteristics of the bullet. It is the hole that the bullet leaves that causes death. The width, depth, and speed of penetration are the characteristics to measure to determine lethality. There are threshold velocities at which point a particular bullet begins to expand and penetrate differently than it would at higher velocities. These need to be known. For all intents and purposes bullet impacts at velocities below 1500 fps. need to be considered as one to one and a half caliber hole punchers as there is little or no wave effect coming from the penetrating bullet that will damage tissue. At this point energy is meaningless. Momentum and diameter of the bullet are the determiners, and of course, the all important, shot placement.

    Energy, or more properly kinetic energy, is 1/2 mass times velocity squared. Momentum is mass times velocity. As you can see velocity is much less important in momentum and the importance of mass, or weight, is much greater. From this and the above discussion it is easy to see that on long shots where the bullet may be impacting at less than 1500 fps. a heavier bullet will have a greater lethality potential at that point than a lighter bullet traveling faster.

    [ 07-20-2001: Message edited by: Warren Jensen ]

    [ 07-20-2001: Message edited by: Warren Jensen ]
     
  9. Roadrunner

    Roadrunner Well-Known Member

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    Warren,

    Like I said, "as it's dropping through the sound barrier, it becomes somewhat unstable and therefore less predictable"; glad to see we both said exactly the same thing.

    However I would offer a different viewpoint about energy; I would maintain that energy is not "meaningless". Any bullet which does not exit an animal has in-fact transferred all its' energy to the animal. At long ranges probably the only known variable is energy. The amount of expansion of the bullet has as much to do with the design and construction of the bullet as does the amount of energy acting on it. One would obviously choose one's bullet based on the particular job one was trying to accomplish; much like one chooses a caliber based upon the job one is trying to do. So in trying to select the appropriate bullet, one needs to know the energy at a given range - from this one can select bullet type and decide if this combination is sufficient to accomplish that which one are trying to achieve. Even at quite low velocities one can achieve complete energy transfer by using frangible ammo.

    Hope this clears some things up for you.

    Regards,

    RR
     
  10. Warren Jensen

    Warren Jensen Well-Known Member

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    Roadrunner,

    Transitioning through transonic inaccurately is not a given. Folks have been doing this accurately for about 140 years. Sharps rifles shooting 45-90 and 45-120 start supersonic but go subsonic rather soon and do not have time to overspin. If you assume it cannot be done at close or long range or ever ultra-long range then you are ignoring the facts and physics.

    Energy is not a good measurement of lethality. On impacts of less than 1500 fps momentum would be better, but only with bullets of the same diameter. The concept that the energy has to be transferred to the animal is not good science. I can make bullets, even in large calibers, that will transfer 100% of their energy in a very few inches. They will not be lethal in most cases.

    [ 07-23-2001: Message edited by: Warren Jensen ]
     
  11. steve smith

    steve smith Well-Known Member

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    RR
    I'd have to disagree there. The amount of energy the bullet uses up in penetration matters not. What kills the animal?
    Either a CNS hit or the interuption of O2 to the brain. Substantial disruption of the blood flow to the brain is caused by the bullet tearing through blood filled organs and or arteries.
    Take a barnes X, lets say that it expands the same every time. You shoot an animal in the lungs broadside, first with MV high enough to have full penetration the second with just enough to lodge just under the hide on the far side. Which did the job better? The end result is an animal that has big hole through both lungs. Whether the bullet stayed in or not doesn't effect the killing capabilities of a bullet.
    Just my opinion!

    [ 07-23-2001: Message edited by: txhunter ]

    Warren. Your just a little to quick on the draw for me. Somebody always gets there before me.

    [ 07-23-2001: Message edited by: txhunter ]
     
  12. Warren Jensen

    Warren Jensen Well-Known Member

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    The correlation between energy and lethality can be made using the following logic:

    As bullet impact velocities begin to climb above 3000 fps. the diameter of the secondary wound channel, or that tissue outside the bullet hole itself damaged by the wave effect, begins to grow at a geometric rate. The secondary wound channel on impacts of 3500 fps. is dramatically greater than that at 3000 fps., and so on. Assuming that the bullet holds together, which at these impact velocities it usually won't, the lethality of this secondary is dramatic. Observations over the years have been made to the effect that this incremental increase in velocity was responsible for greater than expected lethality ergo the use of the energy equation which gives velocity a squared value in the equation. It is not the energy or the release of energy that kills. It is the wave effect that is much more pronounced when velocities of penetration are greater than 3000 fps.
     
  13. BUSHPILOT

    BUSHPILOT New Member

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    The problem isn't about energy. It is shot placement. The worst the shot placement, the more energy you need. A 22 LR will kill most animals at even 100 yards.
     
  14. J E Custom

    J E Custom Well-Known Member

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    This will always be a controversial subject but the energy requirements
    that you read about are supposed to be a guideline "NOT A MUST" based
    on quick one shot kills in the heart/lung area(Where most shots are made)

    A case in point, Just the other day in the newspaper there was a horse
    and her 7 day old fold that had been shot with a pellet rifle by some vandals.

    The fold died a slow and painfull death because the pellet had gone through
    it's heart.

    Assuming you make a perfict shot every time you will not need these energy's

    But this is not a perfict world and some times if the animal runs off he/she
    may not be recoverd.

    I like to try and use these energys when possible but sometimes have to take
    a head or neck shot if I feel like I dont have enough gun for the animal or the
    distance.

    Shot placement and bullet choice are the most important but enough energy
    can mean the difference in recovery of the animal or not.

    Just my opinion
    J E CUSTOM