I have read accounts of a bullet allegedly knocking a massive animal over or backwards.

However it has always been my personal experience that if an animal fell down immediately upon being shot, it was from nervous system shutdown or breaking critical bones (back, both shoulders). Or if the animal fell down later, it was from blood loss.

But I have not ever seen an animal knocked over or backwards by the impact of the bullet itself.

Is it even possible for a bullet to have enough momentum to actually knock a massive animal over or backwards? For this discussion, let's only consider animals weighing more than 500 pounds.

500 I have had this happen to me twice using big bore heavy bullet rifles. They were indeed going backwards just like they had a bungi cord tied to then and back legs collasped, letting their rearends fall backwards. Both were shot in the front chest area.

let's see...
can a bullet cause oh, 1200# of cape or 1800# of eland to be PUSHED/Knocked backwards.

NO

the animal can react to a sublethal hit, by flipping/jerking/flailing about, but can a BULLET from a shoulder fired weapon do that? It penetrates, slowing by friction.

Take a smaller example, a 100# whitetail, at 75 yards... 257 roberts, 100 gr speer bullet, ~3100 fps. bullet dentonates, no exit, deer falls in it's tracks, but it's head raises just a hair. that critter just took 1800# of energy,, an 18 to 1 ratio, and it's tiny butt didn't move... my oldest destroyed it's heart, lungs, and onside shoulder...

now, take a 1200# buff, and a 6000# dgr.. that's only a 5 to 1.... not a chance.

Crigger, what i think you saw was reaction, not a bullet causing an ACTION.

jeffe

I saw a photo of this very thing on a bison bull once. The bull was charging a prone hunter. Sure don't remember what he was shooting either. It was very well published I think back in the 70's. I think it was hit in the brain. The bull flipped right over.

[ 12-26-2002, 22:28: Message edited by: Aspen Hill Farm ]

No way in the world can your bullet knock an animal down. Any sudden motion of the animal in response to the bullet's impact is a muscular response of the animal and not due to momentum transfer.

As you learned in high school physics, momentum is conserved in the collision of your bullet with the animal. Let's consider a 500 grain bullet hitting a 500 lb. aminal. The animal weighs 7000 times what the bullet weighs. If momentum is to be conserved, the animal and bullet together, after the collision, will be moving a 1/7000 the velocity of the bullet. If that bullet was moving 2800 f.p.s. when it hit the animal (and my hat is off to you if it was), the animal/bullet combination is moving 0.4 f.p.s. (0.3 m.p.h.)after impact. That's the most motion your bullet will impart to this critter.

Would that "knock the animal over"?

To answer that question, we just need to know whether a 500+ lb. animal would lose its balance if it suddenly found itself moving 0.3 m.p.h. faster or slower than it was moving the instant before that.

Let's consider a >500 lb. animal standing on four feet in a horse trailer that is moving along at 0.4 f.p.s. (0.3 m.p.h.). If the truck pulling that horse trailer slams on its brakes or hits a bridge embankment so that it stops instantly, does the animal fall over? I hope not. There would be a lot of bruised up horses and cattle walking around if they couldn't stay on their feet through such a small jolt. I'll tell you one thing for sure that would not happen. The cow or whatever would not go flying end over end in a minor collision like this, and it would not be taken off it's feet sideways ending up on it's back.

Another way to impart the same momentum to your big animal to test the knockdown hypothesis would be to have another animal the same size bump into your animal at a very slow walking speed of 0.6 m.p.h. I don't think that would even put a sleeping cow over on its side.

I'm not disputing that a big animal goes end over end or gets rolled sideways when a bullet hits it. I am absolutely certain that the animal has not done this because of momentum or kinetic energy imparted to it by the impact of the bullet. There is just not enough kinetic energy or momentum in the bullet to accomplish such a knockdown.

On the other hand, there is plenty of chemical energy stored in the muscles of an animal to make it execute an impressive acrobatic display in a reflexive response to a big bullet hitting it hard.

H. C.

HenryC470......I have viewed several of Mark Sullivans types and did in fact see were his big double put the stops to a couple of animals with that 600 Nitro of his. Now these animals went backwards at the smack of the bullet. Call it nerves or what have you, those animals stopped in their tracks and went rearward. I myself hit an impala with a 338 mag and it did a rearward flip.
I know what I saw.

It just can't happen. the animal might REACT, but the bullet aint gunna flip any large game. might blow a bobcat to hell, but that's a different story.

here's 470 mbogo's results page, of POINTBLANK shooting a 35# weight...the jeffe-ry moves this weight, that weighs THIRTY FIVE pounds, less than 30 inches. when you do the weight conversion, that 35#/1200# (buffalo) and then multiply that result into the 30"... it's like .875" or 7/8 of an inch. BEING HIT BY A JEFFERY AT POINT BLANK, if it was on bearings, could move 1200# all of 7/8" of an inch.
http://www.470mbogo.com/BigBores/BigBores6.html

Sorry, Chigger, you might have saw the animals' REACTION to being hit.. pulling away, reflex, jerking, from the flash, noise, bullet and impact, but you did not, as it can not happen, see the BULLET cause this. a flip , other than in EXACTLY in the bullet path, would only and exactly indicate animal reaction (muscles) rather than bullet ACTION

Take, for instance, a 5x100# bags of sand, and shot it with whatever HUNTING gun.. 500 jeffe-ry for example. The sand will not move. there are no differences in inert matter, to bullet placement, for what we are talking about.

it's a myth.. and those that have taken a good deal of game know this. Like people fliping over from being hit with a 10mm.. nope, pigs just go lights out... dead as a rock, and falling at the same speed.

jeffe

[ 12-27-2002, 01:24: Message edited by: jeffeosso ]

It's just nerves,

if I wack a roo in the head with a 22/250 every now and then it does a back flip as though the bullet spun it over. But it's just a nervous systym reaction, a 50 gr .22 cal bullet is not moving anythin bar a rabbit. Sam would apply to these bigger animals. The flipping backwards etc. is just a bodily reaction that may give the impression of being knocked down etc.

It's just simple math here folks. Nothing your likely to fire from the shoulder is gonna move a big game animal from bullet energy, or momemtum.

there are 7000 grains in a pound so to see what real energy a bullet has on impact all you need to do is multiply the bullet weight in grains time the FPS and divide by 7000. you will see what the functional impact energy is.

As an example my 458 Lott with a 500 grain bullet at 2300fps would likely move

500 X 2300 = 1150000 / 7000 = 164 pounds

That same load has a listed ME of 5875 FPE

FPE and actual energy are completly different measures of work. As you can see the 164 pounds of Actual energy is not enough to move a 1200 pound buffalo or anyother large animal for that matter. This is also only if the bullet remains inside. If the bullet passed through then even less transfer of "movable" energy would exist.

Heck with this example a 458 Lott with 500 grain bullets would only equal the size of many smaller American and African big game animals. Certainly not the power one would expect to see from a rifle capable of actually moving so much mass. The vast majority of Big game rifles are of much less then 5000 FPE. As another example a 375HH with a 300 grqain bullet at 2600fps has 4500FPE but only 111 pounds feet of energy, or the energy to actually move something.

111 pounds is not a very big "big game" animal. I have seen plenty of jackals, steenbok, duiker, caracal cats, and impalas hit with the 375HH and not a single one has ever lifted off the ground and been slung through the air. Although parts of them have been disconnected and moved a fair bit away from the majority of the body mass!

I shot a 220 lb doe at about 90 yards with a 7.62x39 Bushnell scoped mini 30. The animal was knocked off its feet and never got up. I had to finish it off with a head shot (the least enjoyable part of the hunt) but the bullet penetrated both shoulders and left a blood splattered hole in a 6" pine tree on the other side of the deer. After that shot four other hunters at my camp bought mini 30's, which work really well in the thick brush,and rock ravines around Parry Sound Muskoka.

I should have continued the last post with the statement that this was not a massive animal but also it was not a massive round. I shoot 200 grain Nosler partitions through my M70 300WM that have had a less visible effect on only slightly larger game. I guess the point is that under any given but variable circumstance anything can happen.

If a bullet hits an animal bigger than you hard enough to push it backwards or "knock it off its feet" then you are going to be knocked back more than a couple feet when you fire the rifle. Newtons second law (for every action there is an equal and opposite reaction).

NO unless you're useing a 16" shore battery!

Seems like the overwhelming opinion is that it is NOT possible.
However, a friend of mine spent many years in Africa working as a PH. He had thousands of great photos. One that sticks in my mind was a photo of an adult zebra that was lifted WELL off the ground from the impact of a bullet launched from a 460 WBY. Much higher than one would attribute to nerve/muscle reaction.
Just my observation.

As other's have said, physics doesn't allow for a bullet to knock an animal backwards, there's not enough momentum there. If you want to prove it to yourself then go cut a log out of a tree a few feet long, enough to make it weigh 150# or so (the size of a deer). Stand it up then back up 30 feet or so and shoot it in the middle with your favorite rifle and see if it moves. My guess is you won't move it one millimeter. If the bullet won't move a 150# log then it won't move a 150# deer.

[ 12-27-2002, 04:35: Message edited by: boltman ]

JJ, it is even simpler than you stated. If you were trying to equate momentum ( Mass time velocity) you have to divide the weight by the acceleration due to gravity. So the 500 divided by 7000 is then divided by 32.2 once you multiply that by the velocity you will have the momentum of the bullet and it is not in pounds but in pound-seconds. It does not relate to the weight of anything but only to mementum. What you showed as 164 lbs is actually around 5 lbs-sec. Not related to energy at all. The kinetic energy is the mass times the velocity squared and then divided by 2.

Your premise was right though about this not being enough to knock anything down.

Harelytwo's 220 lb doe was also not "knocked off her feet". Her nervous system was destroyed and gravity took over. The energy available if the doe was standing right at the muzzle would have been equivalent to the recoil you feel from the shot. Equal and opposite reactions at that stage. Once the velocity starts to drop down the energy goes down accordingly.

Gentlemen,

I am going to the other end of the scale.

Can someone explain to me the following please.

I shot an impala, may be 60 yards away, with a Barnes X 300 grain bullet comin gout of the muzzle at around 2700 fps. The animal was facing us feeding.

The bullet entered his body at the junction of the neck and shoulder, penetrating his body lengthwise all the way, stopping just under teh skin next to his tail.

That animal showed no sign of being hit, apart from hopping around as if his front leg was broken.

We all know the weight of an impala, and the energy that bullet has.

So, my question is, why hasn't that impala been lifted off its feet and thrown backwards several yards?

Saeed:
It's that wimpy 375/404 you use. It just simply is not adequate for dangerous game, like deer.

In my limited big game hunting, I have found that to really knock a dangerous animal backwards, like a squirrel, at a range of, say 10 miles, requires at least 2900 fps velocity coupled with at least a 4.000 caliber projecticle, with a minimum weight of 259,000 grains. This round should give you a 29" wound channel, adequate for most any animal, even a squirrel.

This round gives you a 429,200 Taylor Knock out value.

Sufficent for even the largest squirrel.

Of course the recoil, at 4,837,842 ftlbs is a bit stiff...
Merry Christmas

Before we argue this to death, let's everyone just stop and do the math here. The idea of a bullet KNOCKING anything anywhere is mathematically impossible...and I have seen very dramatic live demonstrations to prove this point.

A man put on two bullet proof vests and held a huge phonebook against his chest and had a fellow shoot him square in the chest from a range of about 3 ft with a .308 150 gr bullet.
It scarcely rocked him on his feet.

We have all seen animals do funny things when shot...but regardless if it is sprouting wings and flying away or doing a back flip, it is nothing but the nerves and muscles of the animal reacting to the bullet impact.

Consider how your head would SNAP BACK if I gently poked my finger in your eye. I might apply 1 ounce of force that would get the reaction out of you as if I drop kicked you in the face!

Saeed makes a good point in the opposite direction with his example.......but both examples show the same thing.

We now return control of this thread back to those of you who are determined to argue what you saw VS what is physically possible.

I once shot a bull elk that flipped over backwards. It was quartering towards me at 35 yards and I shot it with a 300 Win Mag and 200gr SGK's. It flipped over so hard that the tines of its antlers stuck into the dirt. It was perfect for gutting!

So, yeah, bullets must lift animals off their feet.

Other than that last part, the story is true. It was quite a site to behold.

Canuck

I have done a "knock down" test this summer. I put up a 25 l barrel full with sand. The weight was about 40 kg. And I put it up on a round table. And when I shot it with my .460 Wby (500 grain bullet at 2500-2600 fps) The barrel was lifted from the table and it fly about 1,5 yards away. And I dont think that a barrel filled with sand can get a nervous system shock.

The nexy summer I am going to make a beter test. I am going to put up a big barrel with sand or something and the weight will be around 100 kg. Then if it can knock down that barrel I will belive in "knock down power"

JJHACK!

Do you mean that a .458 Lott have a push energy of 164 pounds???

A .600 Overkill with a 900 grain bullet at 2500 fps. Will then give a push energy of 900 x 2500 / 7000 = 321 pounds. Oh my That is the weight on a small swedish moose.

Lets also take a .700 BMG IMPROVED 1200 grain bullet at 2600 fps. 1200 x 2600 / 7000 = 445 pounds.

It can be nervous reaction as Pecos45 said about getting poked in the eye, or it could be a combination of that and the balance point of the animal when shot. I have video of a big buck deer shot from a treestand with a bow. The deer basically lifts his front end off the ground and falls backward on his ass. That deer was looking straight forward with his head up; when the arrow hit, his reaction and balance point would have been backward.

Gentlemen:
It ain't going to happen! I have had animals rare up and fall over, ;but this is only a reaction to the shot. I have seen hundreds of animals shot with all kinds of bullets a bore sizes. If every animal the size of deer was shot with one of the3 super 300's then every one of them would be knocked down and then have to get up then run off. I have shot hundreds of large bore rounds into my plywood penetration that weighs about 65# that sets on top of an empty barrel. I have yet to see more that a slight rocking of the barrel (and that is, because the bottom is slightly bulged) If those express rifles
and that inclludes (overkill).460 weatherby then how in the world can a bullet move a large animal
which has less resitance than plywood be moved.
I think this is why eyewitness's can come up with differing opions when viewing the same incident.

Socrates I am glad you said that about that famous 375/404 and not I.....heaven forbid man your playing with TNT.....

To answer my opinion about the Impala shot, Ummmmm
perhaps that blessed Barnes bullet did not open as it should and Walter only filled the case half full of powder.....sound good eh!

Socrates I am glad you said that about that famous 375/404 and not I.....heaven forbid man your playing with TNT.....

BOSS!!! To give my opinion about the Impala shot, Ummmmm...............perhaps that blessed Barnes bullet did not open as it should and Walter only filled the case half full of powder.....sound good eh!

Don’t know exactly how this relates to the subject at hand but the only time I have actually seen anything shot and knocked off its feet was small people shot with a 50 BMG. Now, having said that, the same 50BMG, mounted on the front of an airboat, had to be fired in short burst and use a slow burst rate or the recoil of the big fifty would seriously slow the airboat. I have been told the same thing happened to the P47 and the P51 when they fired all of those fifties at once, the entire aircraft would shudder and literally stop if the trigger(s) were held down.
Interesting subject and I wish I knew more (and UNDERSTOOD) the phenomenon of reaction to bullet strike.
"Shoot straight, shoot safe and shoot a lot!"
Regards,

Customstox, I never went to Yale, Harvard or Princeton........But I had a sneaky suspicion JJHACK missed a class or two on that Math he was trying diligently to have us all swallow like a worm on a hook.

I guess that is what is refered to as needing to go going back and take a refresher course in your math 101, for what you missed while hunting hey LOL.

[ 12-27-2002, 23:14: Message edited by: Chigger ]

When you fire a shot the bullet and the rifle basically now have the same energy as the bullet exits the barrel....fortunately for us (isn't physics great) the bullet weighs a lot less than the rifle 'cuz if they weighed the same they would both have the same velocity and thatn't wouldn't be good......so if the rifle doesn't knock the shooter down at the point of max energy, how can a bullet physically push or knock an anmial down (typically much bigger than you with 4 legs to support it) down range. Can't happen.

DB Bill thank you sir for the education in physics, it sure was a lot easier to understand than that other jibberish formula of JJ's even if his was a little on the rusty side of the round ball.

How about I just take what Mr. Hoffman said about it all, and run to the bank OK.
No need to cloud things up anymore than has been done already. Besides I trust that Ole Boys word on huntin facts......."Wyatt Earp" never spoke no true-er ta folks.

DB Bill!

Have you ever think of this: You say that the bullet will have the same energy as the recoil you feel in your shoulder when you fire the rifle. But if the weight of a .50 BMG would be 6 pounds then I think that it would knock you to heaven. So the bullet has to have the same energy if the rifle have a weight of 40 pounds or 6 pounds. Do you understand?

There was nothing at all incorrct with my math or my presentation. Mr. Worthing added additional information which was useful for those who can understand it. I saw no reason to embelish the already complicated issue with further details. The same information I posted is not "news" and has been used in a nearly identical explanation many times by dozens of well known Authors starting with Jack Oconner and Elmer Kieth. I suppose they were trying to get a fish on a hook as well!

On the other hand I suppose we just need to consider the source of that post!

Chigger,
JJ was on the right track, he just missed a step. Nothing serious but along the lines of what he does, I would rather be able to take a cougar like he and his buddy did than to fool around with momentum formula which don't do much for my enjoyment.

BTW, Chigger, why the cheap shots, do you have something to offer other than your weak sarcasm?

what may be the most famous shot filmed is a bit hard to swallow too.
JFK takeing a FMJ to the back of the head, his head snapping backwards towards the bullet entry and a piece of skull popping off at the entry sight .... yeah right. I saw a documentry on the warren report,where a doctor said " yes, thats quiet common"

Overkill....please don't make the mistake of trying to compare apples and oranges as the shape of the projectile (and penetration) will have something to do with the effect so you cannot compare a rifle's butt to a bullet.....plus the fact that humans react to bullets differently than animals for a variety of reasons.

You might try this experiment. Take a post with a diameter of let's say 6" and with two friends run with it and hit a door...note the reaction of the door. Do the same thing with a 1" diameter broom handle but run much faster...note the reacion.

What do you think would happen to the door in each case? Why? Do the experiment and report back.

again, NO

but, let's say you are shooting a 20mm vulcan, and hitting a rabbit (made out of kevlar) the intial reaction (how many times to I have to say this?) would be exactly away from you. no backflips, not back steps, as a matter of fact, unless you shot it neck (0degree deflection) to tail, it wouldn't move directly backwards at all.

<back from the green hell of shreveport>
jeffe

The energy of the exiting bullet. plus it's assorted gases and powder debris and the moving rifle in the opposite direction are not equal. The momentum of the two are equal.

If you have ever used the recoil calculator on Humtamerica http://huntamerica.com/recoil_calculator/ you will find that when the weight of the rifle goes down,the recoil (energy) goes up. I wrote the formula for the site and their programmer did his magic and put it in a format that it could be used. It is a long standing mathematical formula and it starts off by realizing that the MOMENTUM at the time of firing is equal between the rifle moving backwards and the bullet, powder and gases moving forward. The formula uses the information and the muzzle velocity of the bullet and its baggage to calculate the velocity of the rifle in the opposite direction. You then calculate the energy of the rifle by 1/2 x mass x muzzle vel squared. If the rifle's weight is reduced to one half the velocity is doubled. The resulting energy is twice what the heavier rifle would have been.

The kinetic energy of the moving bullet is a measure of the energy that is stored in the moving bullet and is available to do work. A lot of that energy will be taken up in destroying tissue, heat, noise etc.

We are dealing with momentum. Just like shooting pool with different sized balls. If a ball that is used as a que ball stops when it hits a ball, the one that is hit moves with the same momentum as the first. if the ball that is hit is bigger, it moves slower and proportional to the weight.

If you have a 200 grain bullet moving at 2800 fps and it strikes the aforementioned 220 pound doe (damn that is a big one- lets call her Bertha- for obvious reasons), then the bullet and Bertha will move at a speed that is the weight of the two divided into the total of the bullet times its velocity.

So now we have 200X2800/7000X32.2/((220/32.2)+200/7000x32.2) = 0.363 fps which is about 0.25 miles per hour. That is the maximum velocity that the bullet can move the deer given no losses due to bones etc. Like DB Bill said it "can't happen." I just got there from a different angle.

[ 12-28-2002, 08:41: Message edited by: Customstox ]

Customstox.....thank you sir for informing me of JJ's mishap......Frankly I don't care if JJHack misses his BUS!!! This is as nice as this old country boy is going to put it.

Chigger....I must admit this one has me stumped.

I don't understand your animosity toward JJHack as he's one of the more reasonable, well-informed posters around who doesn't leap to conclusion or make hasty judgements..he has a lot of experience and doesn't mind sharing it. He doesn't use profanity, he's one heck of a story teller and except for a regrettable permanent "hard-on" for an idiot he calls Latigo he seems like the kind of fellow you'd want to know better. He does, however, have another fault....he has the kind of life hunting I wish I could do.