View Full Version : My idea of knockdown

March 6, 2012, 10:01 AM
For most people it seems Knockdown and Stopping Power is the same thing. Lets assume that's true, because the required result is the same: namely the target falls over or is immediately stopped in its tracks. I studied the Thread on knockdown and saw the mythbusters video which explains it very well. I noted the baseball knocked the dummy down as good as any rifle. I know of a school teacher hit in the testicles by a baseball and he went down immediately and stayed down for quite a while. I have many formula's which are supposed to reflect Knockdown/stopping Power. The two with the most merit (because the have a game chart is Taylor's and Thornily. I have read that in Taylor's formula a baseball rates like an Elephant gun. A baseball will transfer energy but it doesn't penetrate or behave like a bullet. So what do I know.
1. There is a 15% chance of hitting head or spine on a human target for instant stop.
2. Otherwise a human may continue to advance/fight for a further 10-15 seconds or more.
3. A more powerful gun will not increase the 15% stop chance but it will almost certainly reduce the advance/fight time frame.
What these formulas are supposed to do is rate firearms. Which is best I don't know but none of them try to tell you a 22 is a good elephant gun. What they all do is suggest which gun in a list is more likely to instantly or very quickly stop a target.
Martin & Osa Johnson on Safari (1900ish) . Osa shot a Rhino (in self defence during filming). She used a Winchester 405. Taylor/Thornily numbers are 38(50-100)/168(250), numbers in brackets are the required numbers for a Rhino. Osa waited until the Rhino was about 25yds away and shot it between the eyes, it skidded to a halt at here feet. I feel she could have done the same thing with an M16 with AP bullets Taylor/Thornily = 5.8/30.6. Either way she knew she would have only one shot and given the choice would have chosen the Winchester.
Finally I don't. Know why the Knockdown thread was closed but suspect it was because the arguments were going round in circles. Read this and enjoy/agree/disagree, I would have set this up as a poll if I knew how to rather than start another circular argument.

Art Eatman
March 6, 2012, 10:57 AM
I started in with a .22 in 1940. '06 in 1950. I've done in a fair number of critters through the decades.

"Knockdown" is not something I've ever really worried about. Empirically, a .22 is fine on little stuff. Centerfire for bigger stuff. Great big centerfire for dangerous game.

If you break the shoulders on a four-legged critter, it can't go anywhere at a rate of speed which would endanger the shooter.

Medico-scientists have stated that heart shots on the monkey-clan (which includes people) stops/kills faster than on, say, deer. It apparently is a physiology/adrenalin thing.

All of which is a circuitous way of getting back to shot placement. :D You pop Bambi in the white spot and he's through for the day. .222 through '06, I've noticed.

March 6, 2012, 03:22 PM
I pretty much agree with Art. Knockdown and stopping power really aren't things I typically think about.

Knockdown and stopping power really play small roles when compared to bullet performance and placement. Use an appropriate cartridge, a bullet that performs well for the task at hand, and place that bullet correctly. All else falls into place pretty naturally.

I like to hunt with a 7mm rem mag. This cartridge works well for me, but certainly works no better at killing animals than any number of other cartridges out there. One could argue the merits of the .243, .270, 30/30, 30-06, 7mm mag, .300 Win mag, and others 'till they're blue in the face. The only real differences are the size of the game that can be taken with each, and the distance at which it can be taken. All can perform admirably in the hands of a competent rifleman, and all can fail in the hands of the inadequate.

If and when I shoot a deer with any of the above, it's the bullet's job to destroy tissue and organs as it passes through the animal. If it does this properly, the animal dies or is immobilized quickly by damage to the CNS, and/or damage that causes rapid blood loss that results in blood pressure dropping. Neither case has anything to do with knockdown or stopping power of the cartridge used.


March 6, 2012, 04:10 PM
I am with Art and Daryl on this, knockdown/stopping power is not what I look at when picking a cartridge for my hunting needs. My big game quarry includes deer and elk, no dangerous game. I look for a cartridge that'll provide enough power to drive a bullet deep into the animal and hopefully out the other side. If on the other hand I was going to chase brown bear through the elder thickets, then stopping power would be high on my list.

March 6, 2012, 04:34 PM
Last couple years I have been going lighter and lighter on deer. Why ruin meat? If the deer is at the edge of a deep ravine it gets a neck/spine shot so it can't run down in. Other than that, light is good.

March 6, 2012, 05:20 PM
I'm with Art, daryl, allenj and gunplummer LOL.

Pretty much wreck the plumbing, landing gear or control panel and you're good.

March 6, 2012, 05:48 PM
Checking to see what I started and I have enjoyed reading sensible replies. There is one other thing stopping power formulas do and that is allow ME to make judgements on my own. You Americans can ask an expert. There was a great gun shop in Edinburgh 9 miles from where I lived as a young man. I read about Powleys ballistic computer and wanted one so I phoned and asked. This was around 1977, the man behind the counter got very agitated and I eventually hung up when he asked for my name and address. He may have thought I was an Irish terrorist. I'm sure if I had given details a visit from the police would have followed.

Art Eatman
March 6, 2012, 06:09 PM
Now, now, Gunplummer: How many times I gotta told ya, don't shoot 'em in the eating part?


In seriousness, I pick out a specific spot on an animal where I fully intend for the bullet to hit. I don't know that my skill level is all that wondrous, but it could be that my "pickyness" level is greater than most. Ergo, it has been extremely rare that I ever ruined what I'd call eating meat. And so I figure that any ruination was my fault, not that of the cartridge or bullet.

March 6, 2012, 06:20 PM

Keep in mind that when considering a cartridge, there are three separate ballistics to consider; internal, external, and terminal.

Internal ballistics involve what happens between the time the primer is popped 'till the bullet leaves the barrel. Powder burn rates, barrel harmonics, and such are involved.

Exterior ballistics involve the trajectory of the bullet from the time it leaves the barrel 'till it hits the target or backstop. This is where you'll find more difference between cartridges.

Terminal ballistics involve what happens as the bullet passes through living tissue. In truth, there is no such thing as "knockdown power", or "stopping power". If the living target is stopped, it's a function of the terminal ballistics of the cartridge/bullet/load combination.

Tables, mathmatical figures, and such can give you some idea of what to expect from a given cartridge, but there are flaws in all of them. They tend to not consider bullet placement, and can't compensate for the stamina and resilience of an individual animal.

There are energy/momentum/KO calculators available online, and a quick search will provide several of them. When considering the capabilities of any given, unknown cartridge, I tend to take all three of these into consideration.

I like the Taylor KO formula, but it tends to favor bigger, slower bullets. I've seen too many animals killed quickly by very light, fast moving bullets to discount them. That's the flaw in that formula.

Energy figures are the opposite; they tend to favor light, fast bullets over heavy, slow ones. Again, I've seen some heavy bullets kill game very quickly, and penetrate deeper than most would expect. That's the flaw in energy figures.

Momentum will give you more information, but it's not a reliable factor in and of itself, since a thrown baseball has a lot of momentum.

But when you take all three into consideration, you start to get an idea of what to expect from the cartridge when experienced advice is unavailable.


March 6, 2012, 06:37 PM
I never depend on a straight on brain shot I've witnessed two pigs shot in what you might call the forehead. Both instances, the animals locked up and fell over stiff as a board only to have them recover and get back up while recovery preparations were being made. One of the pigs was not shot by me. A third pig was in a trap and he took a buffalo bore 45 colt to the top of the head, the bullet exited the bottom of his chest, I suspect it may have went down his throat after going through the head. Same thing happened, locked up fell over and began death quivers. I went to the pickup to get a rope and by the time I turned around he was up and walking, albeit looking a little confused. I don't like those things to happen so I choose other places to shoot them now.

March 6, 2012, 06:42 PM
Bottom line,

SHOT PLACEMENT is the most important factor.

March 7, 2012, 01:30 AM
My idea of knockdown power

a potato gun for squirrel hunting.:D

March 7, 2012, 08:08 AM
I have never been a minimalist. I dont argue the fact that something smaller will get the job done but I've always liked knowing that I have something that is more than adequate. When I build something or have it built, it is not to code, but to +code. Just think.........if the house you bought is built to code, it meets minimum requirements. I digress. Better quit now.

March 7, 2012, 08:30 AM
I have read your post and agree with everything you said.
You like Taylors formula, well here is a little known formula you might like better. Game weight = impact energy x sectional density x bullet area x 25.
Let's look at an M16, at 100yds its energy is about 1010ft/lbs, SD = 0.161, area = 0.039. This gives 158lbs. IF a quartering shot is made use 18 for a multiplier. IF the game is dangerous the multiplier is 12.5. This means that for game of the hoofed variety the target should weigh between 114lbs and 158lbs. IF a wolf saw you first and charged lets hope it doesn't weigh more than 79lbs:D
If you use this formula on a Reminton double derringer you get about 25 which is unlikely to stop a determined attacker unless you hit that 15%.
ps. Most of these formulas take for granted that you have the right bullet for the job in hand.

March 7, 2012, 08:57 AM
ps. Most of these formulas take for granted that you have the right bullet for the job in hand.

Yes, and yet there are a lot of differences in bullets, and how they perform on game.

For an example, I can load a 145 grain Speer SPBT on top of a dose of IMR4350 in my 7mm mag to have a nice load for deer and antelope. I've proven this load many times, and it's never failed to perform perfectly for me.

But if I switch bullets to a Speer 145 grain Grand Slam on top of the same load, I'm perfectly able to take animals the size of elk and bison. I've used it enough to know it works, and works well.

The only difference in the load is the type of bullet used, yet the terminal ballistics of the load are somewhat different. The SPBT expands quicker, so is better suited to lighter game. The Grand Slam is designed for deep penetration through controlled, slower expansion, which allows larger animals to be taken.

March 8, 2012, 10:13 PM
If we are doing a European thing here, Mr. Mikethestick, have you ever heard the rumor about the goose launcher sent to England from the U.S. to check wind screens on jets and high speed trains? Talk about terminal energy!

March 8, 2012, 11:22 PM
"A heavy ball over a light charge will stop a man in his tracks." Long John Silver to Jim Hawkins in "Treasure Island"...

March 9, 2012, 10:42 PM
Good knockdown power is Knockin down your pray & it stays down
Bad knockdown when you say I know I hit that soinso where did he go.;)

March 11, 2012, 07:35 PM
I dont hunt rhino.

For deer just put it in the lungs and you will have venison in the freezer.

March 11, 2012, 09:40 PM
Knockdown interests me..for more than one reason....One thing..I detest tracking....It is much more convenient for the animal to fall where it is shot....I hunt where there is a lot of brush and it could be tough tracking..even in good light...Add to that..I am very color blind....
I mainly hunt deer and hogs.... Big hogs are very tough....many of them run for a very long way after being shot behind the shoulder with a high powered rifle....I have this one figured out..I just neck shoot the biguns....
I use bigger bullets too..since most of my shots are under 200 yds..mostly under 100....
Deer kinda have me stumped...My SIL shoots a buck this past season with a 300 mag...It runs 30 yrds and piles up....I do the same with a 308....It falls in its tracks....The lungs and top of heart are mush....We hunted same stand and about same yrd shot....150 grn bullets....Remington corelocks....

March 12, 2012, 10:10 AM
Shot placement is crucial. But I like to stack the deck in my favor. Yes, I could use a .270 on Elk, but for probably the same price, I can use my '06 and have the peace of mind that it will have that extra oomph. If you place the shot right, either will put them down. The main problem that exists with the higher power rounds is that people put more stock in their caliber choice than their abilities. If you shoot a .270 proficiently, perfect. If you shoot your 30-06 better because you are more familiar with that, fantastic. You don't need a .300 Weatherby magnum to take a bull elk. Caliber is less important than skill, but a little more power can't be a bad thing as long as you know your (and your weapon's) limits.

March 14, 2012, 03:46 PM
I was once attacked by a guinea fowl after I chopped its head off. My father shot at a pig with a rock from his sling shot, it rolled over and died right there. These two instances define knockdown for me as absolutely meaningless.

March 16, 2012, 07:59 AM
Everyone is entitled to their opinion. Knockdown is not an exact science, it is hard to define and perhaps harder understand what is happening. If you don't understand it, it still happens. If faced with a charging Rhino and your gun is not up to the job you don't have enough knockdown. IT'S NOT MEANINGLESS but you would not be around to argue the point.;)

March 16, 2012, 08:25 AM
Terminal ballistics involve what happens as the bullet passes through living tissue.

...... um ...... if you go too light and too fast, the bullet won't go through anything: it'll disintegrate on impact...... leaving "the hickey from Hell"- a large shallow wound that may not be immediately fatal.

..... maybe "Termininal ballistics (in hunting) involve what happens after the bullet strikes living tissue." would be a better description.

March 16, 2012, 08:41 AM
The main problem that exists with the higher power rounds is that people put more stock in their caliber choice than their abilities.

THIS^ !!!!

There have probably been more animals lost due to shooting "more gun" less often (because practice is painful to the wallet and shoulder), than "not using enough gun" ..... that, and guys figure that buying a 300 WINMag will allow them to take 500 yard shots at deer, or using 3 1/2" Magnum turkey loads will make 50 yard shots on turkeys a good proposition...... while accurate and powerful equipment is easily bought, you can't just buy the skills to use it: that has to be developed. That takes some money, true, but mostly it takes time, which is something not many people have much of these days....... which reminds me- I need to go dry fire now .....

March 17, 2012, 07:55 PM
I watch that PH Ivan Carter in the show "Tracks Across Africa" sometimes, and they will indeed use rifles of magnitude that WILL drop animals in their tracks..

Having said that, it's all about bullet placement,,,,"Aim Small,,, Miss Small",.
My own personal experiences show that animals can't be depended on to die instantly..... That's why I spend alot of time and money on my equipment and it's ammunition, and many trips to the range....... I demand that out of myself, to take any game as cleanly and swiftly as I can possible.;)

just my buckfitty.......

March 17, 2012, 10:26 PM
I'm with jimbob86. Bring enough gun and put the bullet where it counts (heart/lungs). You might or might not knock em down right there, but they won't go far. At the risk of starting a verbal fight, I've never given much credence to the folks that talk about neck shots and ear shots and what have you. Under ideal conditions, yes you can take that shot, but I've shot a lot of deer over more than a couple of decades and I have rarely chosen the neck shot. Just pop em behind the shoulder, waste no meat, go get the ATV and tell momma to heat up the skillet.

I never ran into this neck shooting mania till I moved to Texas. I am a firm believer that the neck shooters don't have as much meat in the freezer. There...I've said it! Sooner or later I knew it'd have to come out.:p

Art Eatman
March 18, 2012, 07:15 AM
Aw, 603, it's sort of a distance thing. I generally don't go for neck shots out past 150 yards. Most of my .243 kills have been in the sixty- to 125-yard distance, so the neck shot was a gimme. Off the cuff, I reckon maybe 20 or so of some 24 kills were neck shots. With my '06, commonly at longer distances, I generally went for the heart/lung shot. Probably more of a half-and-half "score".

OTOH, my father was an exceptional shot. I watched him one time call and hit the white spot, offhand, at around 250 yards. Witnesses told of his doing the same at around 500 yards. (He never spoke of such fun things.) I watched my uncle break the neck of a jumping deer as it leapt a fence, at around 125 yards. Stomped the brakes on the jeep, grabbed the rifle, and ruined Bambi's day. And then grinned at me with a, "Bet you can't do that," look. I stayed kinda zipper-lipped. :D

March 18, 2012, 09:59 AM
Welllll....Yes, it's Ok for a qualified and capable shooter to take those neck shots. Upon further reflection, my gripe is really with the folks that I know and have known that are NOT capable shooters but that spend a lot of hot air stating that they only take neck shots. I spent a lot of time entertaining and guiding corporate clients on 100,000 acres of south Texas ranch back in the 80's and I really got tired of hearing all that baloney from folks I knew couldn't shoot worth a darn. I guess that soured me somewhat on hearing about neck shots, and even today my 'BS meter' pegs instantly when I hear the words.

March 18, 2012, 11:07 AM
603..folks who claim to go for neck shots on deer don't bother me....But if they miss..they might just hear about it....:rolleyes: