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Discussion Starter · #1 ·
Momentum By Jack Boswell
We have all watched a movie where one of the baddies is completely thrown across the room, knocked off his horse or catapulted into a wall several metres away by the blast of a shotgun (Open Range) or large calibre rifle (Quigley Down Under). It is spectacular but is it possible; surely you have wondered about that. Most people think that it has something to do with something “technical”. Now I promise to explain this to you without too much technical crap. Please be patient with me because many gun scribes write about these sorts of things knowing less than nothing about the subject. The subject is Physics. Keep reading. Who am I to judge other writers? I taught applied physics (evenings) to Engineering students at the Newcastle Institute of Technology for a quarter of a century. I am qualified. Engineers are the people who build bridges (Ghost in the Darkness), design aeroplanes (Dam Busters) and other clever things. Physics is to an Engineer like “mud” is to a bricklayer.
Let’s get back to the introduction (first sentence); remember the baddy getting hurtled across the room. The buffalo getting “knocked off its pins” by the big English Double Rifle of some adventurous but unscientific gun writer. It makes for a good story but it is WRONG! I am telling you that the “TAYLOR KNOCK DOWN FACTOR” is JUST BUFFALO DROPPINGS! I will prove it. Now I have shot a train load of big game animals too; but this idea has nothing to do with that.
At times people are careless; they are especially careless with their use of words. Normally it does not matter much. But don’t tell your wife that a friend at work is your girlfriend or your boyfriend even if they are of that gender. Science is like safety a mistake can kill! There is a quantity that Physics Students learn about in year 11 called momentum (or impulse which is the change of momentum). Now I am sorry about the technical words but you have heard it before and you are very intelligent otherwise you would not still be reading this. Momentum is what this is all about. Does the momentum of Quigley’s bullet have enough momentum to do what the movie shows? Don’t call it force and don’t call it energy. They are completely different. Trust me just don’t worry about them for the moment. There are no exams here. This is non tech remember.
Most people have heard of Isaac Newton, the pommy bloke with the apple. One of the results of his discoveries is the law of momentum. The total momentum before an impact is equal to the total momentum after. I wish my bank account was like that. Accept my word on this but momentum works out to be MASS (think of bullet weight, or buffalo weight) TIMES VELOCITY. You already know that velocity is how fast it is going. Now we can use any quantity of mass we like as long we keep it the same before and after the collision. Let’s start with the great movie Open Range. “Boss” shoots the baddy with his shotgun.
Before the collision the victim is still so all of the momentum is provided by the buckshot. Let’s call it 40grams (probably less) that is 0.04Kg. The impact speed would be approximately 400metres per second (340m/sec is the speed of sound). So the momentum would be 0.04x400. Now you can check it with your calculator but that is 16 units. The big baddy was say 80kg including the buckshot (probably more). Remember that the total momentum after impact has to be 16 units. So what number when multiplied by 80kg will give you 16? The answer is 0.2metres per second; Not very fast. That is what science says. That is the facts of the matter. Now I won’t go through the maths for knocking the buffalo of its feet unless somebody wants me to. Ask in your comments.
I write weekly column on huntandshoot.com.au
 

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Discussion Starter · #2 ·
ENERGY and the Shooter. Additional information by Jack Boswell
Most people have a bit of an idea of work. Not much fun on a Monday is it? But in physics we are mainly interested in physical work. Let’s think of a brickies labourer on piece rates. He gets paid on the amount of bricks he moves up to where they’re wanted. Got that? In non-technical words: WORK DONE = ENERGY USED = $$PAY. The last bit is the best part of course. “We digger the drain, to getter the money, to buyer the food, to getter the strength to digger the drain.” When you think about it the energy is converted into work. Geeks like me call that the “Law of conservation of energy.” Now you remember that there was also a similar law about Momentum? But momentum is completely different to energy. You can measure your height and you can measure your weight but they are not the same. Got the message? There is only one kind of momentum but there are lots of forms of energy: heat, light, sound, electrical among others. The other main forms of energy that we are of interest to shooters are: Chemical Energy ( stored in the gunpowder), Kinetic Energy i.e. moving energy and Potential Energy ( to do with gravity). Energy is what causes a change. The energy changes its form in the process. The brickies labourer uses kinetic energy to stack the bricks against gravity and in the process his kinetic energy has been changed into potential energy. Now this is where the foot pounds unit comes from. The energy figures in the American ballistic tables originally came from the ballistic pendulum. The kinetic energy of the bullet lifted the ballistic pendulum the heavier the pendulum the more the energy the higher it goes the more energy:
KINETIC ENERGY OF BULLET = FORCE ON PENDULUM(weight in lbs) X HEIGHT LIFTED (in feet).
From all of this we can get the equation for the energy of the bullet using all sorts of algebra and stuff that I promised not to do. So you just have to trust me. Just ignore the bit in brackets.
[ v=u+at, s= (v+u)t/2, v*v =uu+2as, if u=0 , v*v=2as, mv*v =2mas, E=mas, E =1/2mv*v]
Kinetic energy of a bullet = ½ mass x velocity x velocity. Now you do not need to work it out.
Just look it up. It is a real proper measurement. Unlike the TKDF it is a real quantity. Remember that law CHANGE IN ENERGY OF THE BULLET = DAMAGE DONE BY THE BULLET. That is the point! More important, where is that damage done? Momentum does not kill. Damage to vital organs is what kills. But energy can be wasted, on parts of the body which are not vital or on matter other than the target. The shooters who say “that a bullet which penetrate will waste some of its energy” are obviously correct. That is why full jacket bullets are only a good choice under certain circumstances. You can work out the rest. Choose your bullet wisely to suit the application. I prefer to measure all energy in Kilojoules.
 

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There is no "Taylor Knock Down Formula", bullfeathers or no. It is the Taylor Knockout Formula, and it was intended to provide a calculation of which cartridges would better knock out -- literally, as in knock unconscious -- large, dangerous stuff like elephant and rhino when headshot. Whether it has any validity or not is really irrelevant, when most folks don't use it the way it was intended but attempt to make it in to somethng it never was.
 

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I'm glad to have a teacher of Physics here to explain why the 45-70 Government shooting a 500 grain bullet at 1200 fps with black powder seems to work well on Bison, whereas a 22-250 Remington with a 55 grain bullet at 3600 fps seems to preform rather poorly.

Both can be loaded with soft point or solid bullets and both have nearly identical energy figures. Yet though the 22-250 expends all its energy hence equaling damage done by the bullet it fails to duplicate the performance of the less efficient 45-70 which expends far less of it's energy as it generally exits the animal and thus has less damage done. At least according to the above description.

I am curious to know to quantify these things as they have been a in evidence for the life of both cartridges. Not to mention they have been the subject of numerous heated discussions among hunters and shooters for decades.

Perhaps this will only flame up a series of debates, I hope not, as we do have a seemingly qualified insturctor here, who has stated his credentials, to give an explaination of the above dilemma according to the parameters stated in his post.
 

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Discussion Starter · #6 · (Edited)
Reply to ktooth

I hope I got your title right. I can't see your comment from where I am writing now. We don't have any bison in Australia and I have not shot any. I have shot and have seen shot a great many Asiatic buffalo when guiding for Hunt Australia. I have guided many very experienced American and other over seas hunters. They tell me that the Australian Buffalo is much harder to kill than the more dangerous cape buffalo. Now I would not recommend either of the two combinations that you mention. I have also guided a number of bow hunters on buffalo. In all my guiding I always carried a 458 Winchester magnum as back up. There is no way my outfitter would have allowed me to use a 45/70 equivalent. Please read my story on buffalo hunting on:
huntandshoot.com.au I thought the answer to your question was contained in the original article to which you refer. Energy is what causes damage. The arrows that my mate John Johnson used to shoot record book buffaloes has far less energy than the two rifles of your comparison but it takes very little energy to cut blood vessels and bleed the animal to death. John spent a great deal of his time sharpening his arrow heads.
The greater energy of a 458 Winchester does more damage fast. The 22/250 with the bullets you are using does not penetrate enough to apply its energy to the vital parts. If you could shoot it in the aorta or atrium it would kill the bull just as quickly as any rifle. If you paid me enough I could shoot a bison or the much tougher buffalo with a 223. Even at my age! I would take a mate with me with a 458 though. I think you overstate the capability of that black powder gun. I don't mean that all those 'buffalo" hunters of the west did not shoot heaps of bison at a fair range I am saying that it took some time for many of them to expire.
A good punch has far more TKOF than most big game rifle bullets. I really do not know why so many shooters want to work out these magic numbers I have shown you they have no validity. They are silly. Kay Tod I am sorry about getting that name wrong.
 

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Discussion Starter · #7 ·
If you shoot a rabbit in the hip with a 22/250 it will completely disintegrate the rabbit. The 45/70 black powder load will not do near so much damage. Of course both kill the rabbit. They both do the same damage but the bigger bullet wastes most of its energy on the rock behind it. With small animals the energy required to do massive damage is much less than that of a big game rifle. I have shot hundreds of deer in Australia the low velocity 45/70 loads are very unspectacular. It will kill them but they often take a long time to die. I have shot the Australian grand slam of trophy class wild deer in Australia. This includes hog deer, fallow deer, chital, rusa, red deer, sambar and Elk. I have done that three times. I am not just some academic. That does not include culls, does for meat and many feral animals some of them much larger than elk. I could go on and on. See my weekly column on huntandshoot.com.au
The larger animals cannot be blown away by Kinetic Energy. It would take small artillery to do that. I do not know why you want to cobble up some magic formula to "prove" that some caliber is better than another. All of these magic numbers are only examples of circumlocution. With a rabbit there is enough energy delivered by a 243 say to blow the small animal into little pieces no matter where it is hit. If you shoot four deer in the chest with four different 150g 308W bullets; all of the "magic numbers will be the same" for each projectile; that includes the scientific quantities momentum and kinetic energy as well as the fantasy ones. The results will be entirely different depending on the bullet used. If you use a normal deer bullet say a Winchester power point etc you can expect a good outcome. If you use a full metal jacket you may risk losing the deer. The 150 grain grain Hp target bullet may also be risky. They waste most of their damage on the surroundings.That is why the bullet manufacturers do not endorse their use on game. You should be already thinking about what if it is an angling shot? The old style 12 gauge slug will kill deer of course but the first 150 grain 308Win powerpoint is far more effective even though the slug has a massive TKDF . It is an exercise in folly to try to put a number on killing effect. Just ask someone experienced as to what to use for a particular purpose.
 

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Dear Pisgar you are the exactly the sort of client at which this simple lesson was aimed. Can I ask you how well did you do in science at school? One of my ex students is working in cutting edge research into nano computers. Another is senior research scientist at the department of defense. there are many more but that's enough. I wrote the "Road map for science teachers" at Newcastle University. They still use it after 37 years. I thought I made it nice and simple. If you think that there is any validity in your Knock out formula. Just calculate the TKOF for the rifle in recoil. It is much much greater than that of the bullet. Why does the shooter not get "knocked out" by the rifle? I am sure that will have no trouble with the maths.
I bet you have not shot as many big game animals, nor shot as many heavy recoiling as I have. Perhaps you could teach me.
see huntandshoot,com.au to find out about me or the SCI record books of the mid 1980's
Read my post again and I do not believe you will find anywhere I said it was valid; neither did I say it was invalid. I've never headshot mammoth critters,so I don't know. What I did say is, it is irrelevant to the discussions in which it is usually invoked. It was never intended to calculate anything except in the circumstances I noted.

I don't need a professor or aformula or a nano-anything to tell me what 45 years of big game hunting experience has demonstrated to me thousands of times -- that energy alone is worth virtually nothing. It is the work done by the energy that does the trick, and it must be applied in an effective manner. In large animals, that requires a projectile of sufficient size and momentum.

Perhaps, Professor, you could use some remedial reading courses to improve your comprehension?
 

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Comments deleted. On the edge of insults.

Why back out now, Jack? Your comments seem generally to border on insult, and go well beyond whatever border defines pomposity. As. far as I can tell, you are a highschool science teacher with lots of hunting experience. Good on you, mate! I am sure you have lots of valuable knowledge to impart. Why don't you see if you can learn how to do it without belittling and/or ignoring your "students"?
 

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Pigsah:

I deleted his comments because, as you know, that's not how we operate on this board.

Stand easy, this one is closed.

Jack;

PM inbound.

Thread locked
 

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Yup - this thread was indeed headed toward the flaming tar pit of ruffled feathers.

Everyone has an opinion and hopefully, we can express them in a respectful manner.
 
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