Knockdown power myths

[FEENIX]

Two weeks earlier, it took my other hunting buddy 3 shots (2 pass through lung area and 1 through front left shoulder) using factory 180 Barnes TTSX.

BTW, all the shotes were under 100 yards.

Exactly. It is the tissue damage that does the work. Bullets from a shoulder fired gun do not have the physical ability to knock down or push over a big game animal. As in knock them off their feet. If they expire very rapidly and have a muscle twitch at the same time it gives the appearance that they were lifted off their feet. It was not the bullet making the animal airborne, it is not physically possible. Many variables at play in how quickly an animal expires. Only if the cns is interrupted on impact to they drop to the shot. Otherwise they need to bleed out to shut down the cns. Unless spine is hit this usually takes a few seconds and if an animal is in the flight mode they will cover a 100y in 5 seconds. A five second death is great bullet performance. A hunter has to remember that an animal can run really far in a very short amount of time. Sometimes animals hit with big bullets show zero sign of being hit as if they did not even feel it, with soup for lungs. They walk a little ways and tip over.

Hunters should never assume they have knock down power and always assume that they hit their target.

Steve

Exactly! This was my buddies first time elk hunting and used to hunting on stand with average shots of 50 yards in GA.

We told him to keep shooting until the bull elk drops. gun)

 

[brant89]

I try and try to explain to people that knockdown power does not exist, but the conversation usually ends with them still believing their 12ga slugs are going to roll deer over. It's pretty basic physics really; if a 200gr bullet hits a 200lb deer at 3000fps and comes to rest in the opposite shoulder then the deer has assumed all the bullets momentum (slightly different from kinetic energy). Apply Newtons First Law and you get this:

(bullet weight) x (bullet velocity) = (deer + bullet weight) x (deer velocity)

(.0286) x (3000) = (200 + .0286) x (deer velocity)

deer velocity = 0.429 fps

For a frame of reference, that is exactly the same as if you hit it with your car at a whopping .0146 mph. Probably not knocking it over...

 

[Bowfishn]

"Knock down power" is a Hollywood myth. Deer flipping over backwards and such is a physical reaction to the impact. Animals suddenly dropping like hit with lightning is a product of the central nervous system being interrupted. Sometimes a perfect lung shot will cause a "drt" result due to the impact being at the perfect moment to cause the blood pressure to spike and cause an effect like a massive stroke. We all really like it when this happens, but it should not be counted on with any chambering or bullet combo.

Bullets kill by tearing tissue in order to cause rapid blood loss which causes the central nervous system to shut down. So that physical knock down is not the effect of the bullet hitting with the force of a truck. If the bullet hit the target and bounced off like hitting a steel target thus "dumping" all of its energy, no big game animal would be knocked down. You could hit them harder with your fist.

Feenix is correct the 270cal is a fine performer. Pick the right bullet to go with the twist of the barrel and use it to distances that it is effective. That goes for all cartridges. There is no magic.

Steve

It would be quite amusing watching someone shoot a shoulder fired Rifle that has the ability to pickup a 250 to 300 lb live weight animal and throw it back and off its feet. Every time the person shoots it they also get flipped over backwards and land in a heap.Kinda like letting a 1500 to 2000 lb work horse kick you with both feet in the chest.

 

[teflonhunter]

For 30 years I've killed tons of deer in the timber with a 30/06 and never lost one ,never did.Mostly took behind the shoulders shots to limit meat loss. I've never seen one flipped over or anything from the kinetic energy of the cartridge. Average "run" after the shot was probably 30-35 yds. Been hunting with 444 Marlin lever action last couple seasons and seems like the average run has shortened, still to early to tell. Energy level between these to cartridges is near about the same for average distance I shoot. I know some physics say different but to me there is something about a big bore cartridge with a heavy bullet that stacks the odds in your favor. I have shot some coyotes with the 30/06 that seemed to be flipped over when shot , even "pushed" from the impact.

 

[brant89]

I wouldn't argue that the big bore may be getting the job done more efficiently, but physics never lies, regardless of how something may "seem". If the animal is getting "knocked back" it is a result of the animals skeletal muscular or nervous system response to the impact, not from the momentum of the bullet. "Physics is wrong" is the typical response I get from people after I prove on paper with actual numbers that knockdown power doesn't exist. If bullets could knock an animal down you would be in pretty bad shape after squeezing the trigger.

 

[Bowfishn]

I wouldn't argue that the big bore may be getting the job done more efficiently, but physics never lies, regardless of how something may "seem". If the animal is getting "knocked back" it is a result of the animals skeletal muscular or nervous system response to the impact, not from the momentum of the bullet. "Physics is wrong" is the typical response I get from people after I prove on paper with actual numbers that knockdown power doesn't exist. If bullets could knock an animal down you would be in pretty bad shape after squeezing the trigger.

Reminds me of when we did a lot of Chuck shooting in the 70's we often used a 30-06 with 165 gr bullets traveling at 3000+ fps., 10 to 15 lb Eastern Woodchuck being hit by a 165 gr @ 3000 is like shooting a dear with a cartridge that would make the 50 bmg seem like a BB gun. Several hundred Woodchucks and none of them were thrown back from the impact, some would jump straight up in the air clearing a barbed wire fence from the shock on the nerves but no flipping end for end landing several feet behind where they were hit.

 

[Antonio m]

I once killed three elk with my pickup truck at 40 mile per hour and I was breaking hard. There wasn't even an open wound. I didn't even aim! I have also killed bull elk with a 22/250 and did aim -all died instantly.
My point is there is no hard and fast rules but taking careful aim and using a great bullet smaller the a Nissan Titan just might be ideal. I use a .270 win (or similar)and a great bullet is a fine choice and a good compromise,imo. The chambering is less important than using a premium,non fracturing bullet that will go through muscle ,bone etc on a testosterone filled herd bull elk. Muzzle energy is a term that is over considered and the term "knockdown" is semantics,imo. Cheers.

 

[TXAoudadKlr]

Sometimes animals hit with big bullets show zero sign of being hit as if they did not even feel it, with soup for lungs. They walk a little ways and tip over.

Hunters should never assume they have knock down power and always assume that they hit their target.

Steve

Hit a buck two years ago with a 458 Socom doing 1840fps with 300gr TTSX at 80 yards. I fired, and to my surprise the deer acted like he had not been hit at all. He ran 40 yards acting like what the hell was that. A few seconds later as I was about to squeeze off another shot, he staggered and fell over dead. I opened him up and this massive blood clot fell out and saw his liver for the most part was torn in half. Performance appears to be better on larger animals.

 

[Bbear]

My first two elk were taken at the mighty long range of 42 and 50 paces. Both were DRT with a 25-06 shooting 120 partitions. Both were shot in the neck.
First archery elk was shot about mid-way up the body line just behind the shoulder. The elk twitched and jumped forward about 3 feet and looked around. All the while blood poured out until she dropped.
I've taken a few elk with one-shot kills. More with two shots using everything from a 300 mag of some flavor down to the aforementioned 25-06.
The only shots I've taken that caused an animal to do anything but run/walk off or drop right there were the one's shot in the neck while facing me. Two that come to mind were shot in the throat patch. In both cases the deer flipped backwards and landed on their bellies.
I don't attribute that to kp, rather the hit to the CNS causing a reaction of the muscles.
I've seen deer hit with 12 gauge slugs stagger side-ways from the hit (shoulder) as well as being hit by a slug from a muzzle loader do the same. In those instances I would attribute the reaction to the impact on large bones.

 

[arbogb062]

Not too many people's fists are going to have the same impact as this nor a .1mph car hit......... Slow mo starts at 0:18

https://www.youtube.com/watch?v=m4LxFPLMeaY

 

[brant89]

This is a perfect example of why you use momentum and not kinetic energy. Energy has the ability to change forms and directions. In a gun the powders chemical potential energy is converted to heat energy, which is then converted to kinetic energy to the bullet, which sheds velocity as the energy is converted back into heat energy (vapor trail) and sound waves (kinetic energy in the air), and is similarly converted into wave energy when it hits the animal creating the shock wave in the video where much of the energy is transferred PERPENDICULAR to the path of the bullet. This perpendicular energy transfer has no affect at all on moving the deer in the direction of the bullets travel. Momentum on the other hand always continues in the same direction as the largest vector.

As a side note, you might also notice that even with all that energy transfer the deer still did not move in any direction except straight down. Cool video!

 

[Dr. Vette]

The last deer I saw drop in its tracks was the one my 16yo daughter shot last fall...with her .223 Rem. Double lung shot that grazed a vertebra, splintering it up into the spine. I laughed a lot when I saw it drop the instant she shot. She turned to me and reminded me that we didn't have to track it far.

 

[Reloder28]

Taylor KO, energy chart, terminal ballistics, knock down power, ad nauseum. It's all just some musings developed by rocking chair pilots with nothing else to discuss.

 

[Reloder28]

How much knock down power does an arrow have? None.