Thread: Knockdown power

Originally Posted by keengunNic

Ive not really followed this thread too much. But i Just chronographed my new 7mm08 load this morning, 162 amax, rl17 17" barrel doing 2495, that gives me 1000ftlbs at 585m, but i believe impact velocity is more important to look at when using a match bullet for hunting. Not great velocities but an es of 4 was pretty nice to see, gives me every confidence that i can cleanly take animals past 500m.

Not having a crack at all but your post raises a matter - the commonly held belief in 1000ft lbs, Just because Col Townsend Whelan wrote years ago that a bullet needs 1000 foot lbs energy to kill a Whitetail how does that apply to a Red in NZ ? 1500 ft lb's and 2000 feet per second in my view.
Mike Tyson had an estimated punch impact of 1175 ft lb's approx. for reference. So if a bare knuckle Mike punched a stag on the shoulder, would the stag fall dead ?

nope BUT it would sure as hell be winded....and if he punched it in high neck it could possibly be knocked out....now if he poked a hole through it with say a target arrow at same time.....animal may well bleed to death BEFORE regaining mobility......so in one respect its very similar...the ONLY reason shear/pure knockdown power or "punch" is important at all is it hopefully incapacitates animal for long enough for it to die of the other effects of projectile,be that bleed out,lack of oxygen to brain or spinal severing in which case the incapacitation is already there.

In my experience/opinion there seems to be three main factors that will determine how quickly a game animal drops/expires.
1. Shot placement (no secret that cns shots drop animals like lightning and that that rear lung shots are not quick killers)
2. State of the animal when shot (is it relaxed and feeding or has it just spotted/smelled the hunter and the adrenaline is starting to flow?)
3. Energy of the projectile. When assuming lung/chest shots my experience has been that projectile energy (within reason) comes in a distant third with regards to influencing speed of the kill. I have taken deer with “marginal cartridges” through to “excessive cartridges” (375 Ruger, 45/70). I can say without any hesitation that the ones who appeared relaxed at the time the shot was taken died quickly and moved little distance (often dropped right away) irrespective of the sometimes “inadequate energy” of the cartridge used. The flip side of this is that game that was spooked or in flight mode traveled much further irrespective of the “massive” amount of foot/pounds delivered by some of the cartridges used.

fascinating study; https://www.dnr.sc.gov/wildlife/deer/articlegad.html

Originally Posted by Remmodel7

How do people feel about "knockdown power" in large calibres such as the 300s and 338s with 200gr plus pills. You are almost guaranteed a pass through and so I ask how much every is imparted into the animal?. I know there will be a bigger hole but I do wonder exactly how efficient these cartridges are. Yes there are advantages in getting the bullet in target with less wind drift.
We have already been told in this thread of a 1.5 inch tree that got killed behind a goat. How much of the 45/70s energy was used in the animal

45/70 went through the shoulder blade , took out several ribs and shredded the internals before the ramainder of the bullet exited and took down the tree . I use the FTX rounds with the polymer tips at around 2000-2200 fps if I remember correctly . It was admittedly short range , around 25 yards .
In my experience nothing I have shot with the 338 lap mag at ranges out to around 600 mtrs with a 250 gr soft point has taken more than one step , including a large pig taken on the trot at around 150 mtrs . It didn't keep on running and had half it's lung hanging out the exit hole . It wasn't going anywhere .
fallow at 460mtrs was last animal taken with that rifle and all it did was jump up on being hit and was dead before it landed again . I know this because it landed on it's face when front legs no longer worked . Was a heart shot . All have been through and through shots . Nothing has walked or run away .

now that said I have also dropped a massive sow at 100 mtrs on the spot with a neck shot with my evil black 223 . Heart shot a small boar at 50 with same rifle and the little bastard ran off never to be seen again .....

Originally Posted by rewa

fascinating study; https://www.dnr.sc.gov/wildlife/deer/articlegad.html

Yep, seems the best bullet is one that ends up under the skin on the offside having dumped all its energy in the target.
I have some ,223 that I've found when skinning deer perfectly mushroomed parked up against the skin, they expand to half an inch on the way.
With some target bullets in 30 cal on occasion I've been presented with copper and lead confetti all through a shoulder and in the plural cavity with the off shoulder untouched others just messy holes in both and a pass through.
I do however subscribe to the principle of "more meplat more better" with most bullets especially at close ranges and with slowish projectiles.

Been following this thread with interest, reading the different opinions.Having shot animals with rifles ranging from the humble .22 up to 416 Rigby I don't really put much stock in the idea of knock-down power. Have dropped various sized animals on the spot with all sorts of calibers, some have performed out of all proportion to their size/velocity/bullet weight. However I have also lost animals, some well hit with substatial fire-power. Sometimes it's just how your luck runs on the day.
But I reflect on the day, some 41 years ago now,that some arsehole shot a deer I was cerrying on my back with a .270. I certainly knew it had been hit ,impact spun me around a bit and I ended up on the ground. Don't know about knock-down power but there was certainly some impact energy.

Originally Posted by rewa

fascinating study; https://www.dnr.sc.gov/wildlife/deer/articlegad.html

That was a good read. I definitely agree with the statement in the abstract about a lot of hunting related information not being supported by data. For example you will see hunters/ magazines promoting certain cartridges and putting down others based on nothing more than anecdotal evidence. Its cool to see some work being done to producing a reasonably objective study.

Originally Posted by woods223

Been following this thread with interest, reading the different opinions.Having shot animals with rifles ranging from the humble .22 up to 416 Rigby I don't really put much stock in the idea of knock-down power. Have dropped various sized animals on the spot with all sorts of calibers, some have performed out of all proportion to their size/velocity/bullet weight. However I have also lost animals, some well hit with substatial fire-power. Sometimes it's just how your luck runs on the day.
But I reflect on the day, some 41 years ago now,that some arsehole shot a deer I was cerrying on my back with a .270. I certainly knew it had been hit ,impact spun me around a bit and I ended up on the ground. Don't know about knock-down power but there was certainly some impact energy.

I can't even imagine how scary that would have been to experience. You would have frantically been checking yourself I imagine?

Originally Posted by Ftx325

45/70 went through the shoulder blade , took out several ribs and shredded the internals before the ramainder of the bullet exited and took down the tree . I use the FTX rounds with the polymer tips at around 2000-2200 fps if I remember correctly . It was admittedly short range , around 25 yards .
In my experience nothing I have shot with the 338 lap mag at ranges out to around 600 mtrs with a 250 gr soft point has taken more than one step , including a large pig taken on the trot at around 150 mtrs . It didn't keep on running and had half it's lung hanging out the exit hole . It wasn't going anywhere .
fallow at 460mtrs was last animal taken with that rifle and all it did was jump up on being hit and was dead before it landed again . I know this because it landed on it's face when front legs no longer worked . Was a heart shot . All have been through and through shots . Nothing has walked or run away .

now that said I have also dropped a massive sow at 100 mtrs on the spot with a neck shot with my evil black 223 . Heart shot a small boar at 50 with same rifle and the little bastard ran off never to be seen again .....

With bigger cals and also with stouter projectiles in medium cals where the projectile passes through, I believe there is a Venturi effect that sucks fluid out of the wound helping to depressurise the vascular system. Certainly using Accubonds in my 270 I nearly always find globs of blood on the ground. This does not come from blood bleeding out of the animal but is there instantly the bullet passes through. Often animals run a short distance on a hit with an AB, but there will be blood behind where they were standing and normally 1-2 tablespoons full.

I have only really ever used soft points in any of my rifles (except 45/70) . Never really had any issues , as long as the bullet was correctly placed of course , so never seen the need to try any of the other bullet construction designs .
But as we all know , no matter what you shoot bullet placement still is the decider . Nothing walks away from a head shot .
And in my opinion if you want true "knock down power" the closest you would get is probably a shottie shooting slugs at lower speeds . Big flat frontal area of heavy slug to impart energy rather than pass through and possibly knock down the target through pure momentum .