Thread: Interesting theory of what causes instant "knockdown"

https://www.themeateater.com/hunt/fi...-really-a-myth

All this light bullet going very fast business has gotten me excited. I'm currently exploring velocity at both ends of the spectrum, as I want to improve my DRT ratio (already pretty good) but I also want a clinical subsonic deer killer - hence the interest in 8.6 BLK etc. Two very different terminal ballistic categories.

I came across a piece on the Meateater site in a blog (linked) where they talk about what potentially causes instant “DRT” knockdown. Whether there is a relationship between the timing of the animal's heartbeat, blood pressure and the hydrostatic shock wave, causing a fatal spike in blood pressure in the brain.

They don’t produce any direct evidence because they can't find it, but apparently there is a veterinary study in South Africa somewhere on cull buffalo that showed a clear relationship between brain hemorrhage and instant collapse, in a sample of cull animals that were all shot in the same place (H&L chest shots). Those that ran a ways showed no sign of brain injury whereas every single one that collapsed on the spot had a brain hemorrhage. The theory is its all in the timing - over which the shooter has no control.

I thought this was very interesting but as yet it remains unsubstantiated. I really want to find that article because I’m curious to see if this is indeed true or whether it’s something some bright spark has dreamt up.

We've (generally) ascribed instant knockdown phenomenon with chest shots to the Hilar zone and breaking the autonomic nervous system links back to the brain. I know that when I started targeting the hilar with the classic front line of foreleg, halfway up point of aim, adjusting for angle, my DRT percentage went up significantly. Calibre doesn't seem important. .223, .243, 6.5, .308 all achieve hilar bang flops without difficulty.

So, where are we on the blood pressure / brain hemorrhage thing? Any of our South African members come across this supposed study? I really really want to find it but so far nada.

Interesting read....I seem to get a higher rate of Boom Flops with one of my rifles compared to the other. The boom floop (nick named the hammer by my mates..) is a 303 pushing a 203gr round nose out at 2040fps...where as the other one is a 303 using 150gr SP....Both are effective at killing with one shot, but the ones hit with the 303 are usually right when they stood versus the 308 ones which are nearby....But I have only a very small sample size of less than a dozen to go on.....

Fast/light bullets instantly killing regardless of shot placement due to "shock" has been a narrative for at least 50 years.

The difference between animal travel with the Hornady Interlock SPBT in 150gr and 165gr in the .308 is interesting and would seem to contradict the light/fast argument. Ones hit with the 165gr tend to not travel as far, from my experience.

I suspect from that, bullet expansion and increase in frontal area in a controlled manner has more impact (no pun intended but I'll take it) on this than outright velocity and achieving as much energy dump into the target as possible. A bullet recovered under the skin on the far side = perfect. Bigger calibers are better at this I think, if you want bang/flop/kick twice and lights out, try a .45/70...

I have seen animals run considerable distances after taking theoretically perfect stopping shots, and others drop on the spot from what appears to be poorly placed shots, but overall, the quickest stops (excluding head/neck shots) have been with .303 & .30 calibre 150 -180 grain bullets on deer and pigs. Used no more than 150 metres the .44 Magnum certainly never let anything get away, sometimes with complete penetration, but they often went 20-30 metres before they realised they were dead.

John "Pondoro" Taylor devised a knock-down value scale for cartridges way back at the end of WW2.

Find a copy of African Rifles and Cartridges and have a wonder read.

There are only two ways that you can knock an animal down instantly in physiological terms:

1) Direct damage to the brain and/or upper spinal cord.
2) Massive, immediate loss of blood flow to the brain.

How you achieve the above is the subject of discussion.

Originally Posted by fawkes

John "Pondoro" Taylor devised a knock-down value scale for cartridges way back at the end of WW2.

Find a copy of African Rifles and Cartridges and have a wonder read.

I remember reading that and I think the conversation generally was it was easy to debunk. That recollection is going back some but pretty sure that was the case.

https://www.outdoorlife.com/hunting/...wn-power-myth/

Was out with a mate the other day and he shot a deer, we both watched it bang flop, but it wasn't where we saw it drop. couldn't find it. I think he hit it above the spine and the shock dropped it, but then because of not a fatal shot it recovered and left. we had to drop down through a small bush gully and back up so didn't see it.

As MB said, the drop needs to shock the system enough to override brain signals to the limbs

And in some cases even a head shot which munches everything in the control gear still doesn't drop an animal that is on it's feet and running. Sometimes there is a bit of wiggle room in the 'rules'...

I have had that too and even dropped on the spot but 4 or 5 seconds later trying to get up but the back legs weren't working.
Shot was very high in the back but didnt hit the spine itself. By the lack of damage to the spine i assumed it could of got going on all legs again.


Usually death follows before regaining consciousness, But not always. So i learned "DRT" is actually in 2 parts.

1) Instant incapacitation by shock to the CNS and/or other theories.
2) Death followed by blood loss / lack of oxygen.

Always ready now to have another deer get up and bolt after thinking i sacked it and its not getting up again.

Don't know about heart beat...but if animal was chest hit as it exhaled there would be no "gas in the tank" compared to if struck with full lungs...might only be difference of seconds on length of a dead run. My theory is take out both front wheels and they can't drive away...not far or fast anyway.

Originally Posted by No.3

And in some cases even a head shot which munches everything in the control gear still doesn't drop an animal that is on it's feet and running. Sometimes there is a bit of wiggle room in the 'rules'...

Mate…. Really?

Originally Posted by No.3

And in some cases even a head shot which munches everything in the control gear still doesn't drop an animal that is on it's feet and running. Sometimes there is a bit of wiggle room in the 'rules'...

Hmm physiologically impossible