Stopping Power - Knock Down Power

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I have killed close too 100 deer and one elk in my life using archery, muzzle loaders, shotgun slugs, center fire rifles and last year handgun. When it comes to "Knock Down Power" yes there is a such thing as "Knock Down Power" I have shot deer that dropped like a brick. The bullet of course went through the front shoulders (bone) the one elk I shot with a .54 caliber black powder rifle dropped where it was standing. How does this correlate to a human threat? when the bullet crushes bone matter or brain matter the body goes down.

Except that was not caliber but shot placement. If there were true knock down power, people shot in their BP vest would be knocked down & they are not.
When talking service calibers, no such thing. An expanding bullet above the 2000fps, things start to change. Any increase thru temp cavitation in service calibers is marginial, there but still matginal. The bullet wants to expand, reach vitals, poke big holes, thats where its at. A 60cal bullet is better than a 35cal bullet, bigger hole. How it gets to 60cal is less important. Put them in the right spot, cross your fingers they stop.
 
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My guns are required to stop a skunk before in gets to crawl under a shed. If it can do that . It's a good one. {my reality YMMV}
 
“Everywhere” is wrong. There is a such thing as stopping power and knock down power. It just doesn’t exist in pistol rounds. If it did, you wouldn’t be able to shoot the pistol without getting knocked down yourself

There was a soldier in WWII who took a direct fire 88 mm anti tank round in the torso and lived. That's an extreme example, and it obviously was more of a graze, but it does suggest that there's never enough when it comes to stopping power.
 
There was a soldier in WWII who took a direct fire 88 mm anti tank round in the torso and lived. That's an extreme example, and it obviously was more of a graze, but it does suggest that there's never enough when it comes to stopping power.

Did it knock him down? Just curious.
 
It's complicated.

About half the assailants who are shot stop after being hit by the first round, pretty much regardless of the cartridge used.

Those are psychological stops where the assailant, upon being shot, thinks to himself something along the lines of "O.M.G!! I've been shot! Getting shot sucks! I don't want to get shot any more!" and then throws down his or her weapon and either gets down on or fall to the ground and makes every effort to not get shot any more. For these individuals, the round just has to deliver enough terminal effects to notify the individual that he or she has in fact been shot.

The other 50% are where it gets interesting. "Rapid incapacitation" is probably a better way to describe what you need than "stopping power". You get rapid incapacitation by either making a hit on the central nervous system (the brain or the upper portion of the spinal column), or through rapid loss of blood pressure through a hit to the heart or the large arteries above the heart.

A CNS hit is a rapid as it gets. A cardio pulmonary hit that completely stops the heart however will still leave the assailant with about 10 seconds of usable consciousness due to the oxygenated blood that is already there.

If you've hunted and hit a deer in the upper chambers of the heart or severed the large arteries coming out of the heart, you'll note that many will still run 50 yards or so before going down. That's due to the residual oxygenated blood, even though no new blood is being pumped by the heart. If you've hit a deer in the more muscular lower chambers of the heart, you may have noted the deer ran a lot farther before going down. That's because the more muscular lower chambers tend to be a bit more self sealing and will slow the loss of blood pressure.

The same is true with 2 legged critters, and a 2 legged critter can do a lot of killing in 10-15 seconds.

Generally speaking, short of a CNS or cardio pulmonary hit, the more hits you make on an assailant, the more wound tracks are created, the greater the blood loss and the faster the blood pressure is reduced.

Thus you shoot, and keep shooting until the assailant is on the ground and totally out of the fight. It's not about killing, it's about ending the fight.

Hollow points that expand in the assailant have two positive effects. First, they reduce the potential for over penetration in the intended and reduce the potential for unintended casualties. Second, the larger expanded diameter increases the diameter and volume of the wound channel, increasing the potential for a CNS or cardio pulmonary hit, while at the same time increasing the speed of blood loss and decrease in blood pressure.

Hollow points then have the potential to create rapid incapacitation with fewer hits. That then means fewer wound tracks in the assailant. More wound tracks generally means more systems compromised and more damage that has to be fixed by a surgeon before the assailant expires.

10 torso hits from a .22 LR will almost always be more lethal than 2 torso hits from a .357 Magnum. Those 10 .22 LR hits however are far less likely to incapacitate an assailant in seconds, but rather will take minutes or even hours. They will however have a very high probability of being lethal in hours or days.

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The FBI standards are often cited as being essential for self defense ammo performance, but that's not entirely accurate as it's not an apples to apples comparison with an armed citizen self defense shoot.

The FBI's 12" minimum to 18" maximum penetration standard is based on the reality that police officers often shoot at suspects who may not be in a convenient face to face orientation, so the penetration requirement has to consider less ideal target aspect angles, an intervening arm, etc.

Ballistic gel testing is also just a convenient method to compare the terminal effects of different rounds under controlled laboratory conditions. That level of penetration was derived based on field experience observing rounds that were generally effective in the field that also displayed 12"-18" of penetration (with at least 1.5x expansion) in ballistic gelatin.

Assailants are not made of ballistic gelatin and there are plenty of examples of rounds that are effective in the real world, that may penetrate only, for example, 10" in ballistic gel, particularly in the face to face target aspect angles that are more common in an armed citizen self defense shoot.

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In terms of field results, once you get to the .357 Jacketed hollow point level, larger handgun rounds are not significantly more effective at rapidly stopping an assailant. Consequently, I prefer to stay with effective rounds that can more easily be fired accurately and with rapid follow up shots.

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Personally, I carry +P loaded 125 gr XTPs in my .38 Specials, since I'm not comfortable with the lesser performance of a standard pressure round in a short barrel .38 Special. 125 gr XTPs expand to about .52 caliber at 1000-1050 fps velocities.

My preference however in a short barrel revolver is the same 125 gr XTP loaded to 1250-1300 fps, using 8.5 to 9.0 grains of unique. It has substantially lower recoil than a slow burning powder load and gives up little or nothing in velocity.

In 9mm I still prefer the 124 gr XTP at around 1050-1100 fps.

In .380 ACP I like the 90 gr XTP, provided you can achieve 1000 to 1050 fps for reliable expansion. If you can only get 900 fps in a short barrel .380 ACP, you're better served with the 90 gr FTX as it will expand reliably at that velocity, where the 90 gr XTP will not.

The XTP series bullets generally works well in marginal cartridge / firearm combinations (short barrel .38 Special, compact 9mm, any .380 ACP, etc) as it's designed for moderate expansion that allows it to still penetrate to around 12" (and while it's not perfect, or apples to apples, I still like the FBI penetration standards).
 
The terminology doesn't really matter...some calibers, bullet weights and bullet designs are better for specific purposes than others and these are mostly just convenient terms for that concept. I tend to roll my eyes at "knock down power" but don't really find anything wrong with "stopping power."

It's the myths and urban legends about certain calibers and bullets that get repeated on the internet and in gunshops that get really annoying.
 
I know of one situation that the term does apply. In elephant culls on brain shots. On missing the brain but disrupting the cerebrospinal CBS fluid you can knock the animal down even unconscious. The larger the caliber the better the effect. This gives the shooter an opportunity to place a second shot directly into the brain.
Culls involve the shooting of whole herds or family units or in the case of the old ivory hunters they are taking down more than one animal.
I have had only one instance where I stopped the elephant with a poor brain shot taken at an extreme angle but the jumbo so so dizzy I quickly finished it.
A friend of mine a couple of years back while hunting plains game was charged shot the elephant with a 340 Wby using soft pits and knocked it down. This is all on film the herd came charging in so they got out of their not wanting to have to shoot any more animal or get stomped. They came back the next morning the elephant was gone they tracked it for a few miles but no blood it survived. That is stopping power.
 
ENERGY! WHERE THAT ENERGY IS PLACED is ultimately "the most important factor", along with the design of the bullet. I like large/flat/heavy bullets, NOT traveling at warp speed.


Rounded nose bullets are more apt to be steered by tissue and muscle where flat nosed drive straighter. As far as velocity once you have adequate or full penetration this depends on what you are hunting there is no need for additional velocity and bullet construction is critical.
 
There was a soldier in WWII who took a direct fire 88 mm anti tank round in the torso and lived.

And then there was Phineas Gage.

Exhaustively documented, "large caliber" through-
and-through penetration of brain housing group.

Ya nevah know...
 
It’s been stated everywhere that there is no such thing as Stopping Power or Knock Down Power.

So that being the case, what DO you call it?

If I place a shot that knocks you down or stops you, I'll call it well done.

Wasn't that the plan when you pulled the gun?
 
Some YouTube star posts a video talking about no such thing as knock down power and everyone believes him,jeeze luis.
The logic used is that they try to say that the handgun would knock you down when you shoot it , if it had enough force to knock down what you are shooting.
And that is totally an incorrect statement! Percieved recoil is about 1/8 ( depending on the firearm) . So a .45 acp delivering 850 ft lbs to your target is only projecting less than 50 ft lbs to the shooter.
Now go to your garage and grab a torque wrench and torque a bolt to 850 ft lbs. Yep, you will need your neighbors to come help, even with a 4ft cheater bar. When your done, come back and post how 850 ft lbs is not enough to knock you down.
I'll be waiting!
 
#2 not really. The ER doctor and medical examiner can't tell, from the entrance, exit, or wound track, what caliber or weight it was, or whether it expanded or not. Many handgun bullets fail to expand. You can't tell any of this unless you recover the bullet. Bullets that have killed people usually don't look anything like the flowers and mushrooms in the ammo ads.

All this is why I load FMJ in my carry gunss.

I mentioned nothing about ER docs being able to tell entrance from exit or caliber. The elasticity of epidermis is known.

That being said, a projectile that expands, offers more of a cutting surface. Cut/Severed bleeds more than crushed tissue. An expanded bullet also crushes more tissue.

Modern JHPs expand far more often than not. This is also known if one keeps up with those in the science of terminal ballistics. Having recovered JHPs I have personally fired into live feral hogs in the past, not failed to expand. In reading the info from people like Chuck Haggard the JHPs his dept issues (124gr+P GDHP) look similar to the bullets when fired into denim covered ordnance. Often times ending up as a lump under the epidermis on the other side of the entry wound.

I'm really want to address your desire to load FMJs, other than to mention NYPD stopped after numerous through-and-through wounds caused unintended casualties.
 
It's complicated.

No, it’s not at all complicated, unless you want to make it complicated with NASA level analysis. As a related aside, have we ever heard anything about any of the ammo used in the various questionable self defense shoots exhaustively discussed recently on this forum? I bet there was no more research into those loads than I gave to breakfast this morning . . .

Edit: By my penultimate statement, I mean those arguably questionable shoots that resulted in a fatality. At least two over handicapped parking. . .
 
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I have in several strings referred to the excellent book by Urey Patrick and John Hall: CAP - In Defense of Self and Others . . .: Issues, Facts & Fallacies -- The Realities of Law Enforcement's Use of Deadly Force, Third Edition (9781611636826). Authors: Urey W. Patrick, John C. Hall. Carolina Academic Press. Even though directed at LE use of deadly force, most of those are simple inane defensive shootings. The general information is excellent and very valuable.

Anyone who owns a firearm and even remotely considers it a defensive weapon needs to buy, read, and re-read the book. There is a whole chapter dedicated to terminal ballistics, and that chapter alone is worth the price. Likewise, one should also track down the writings of Dr. Gary Roberts, the heir to the founder of modern terminal ballistics research, Dr. Fackler.

Placement first. One simply must know the proper areas to target on a human body when it becomes appropriate to shoot an assailant to defend yourself or others. Many targets result in and reinforce awful round placement, usually too low on the torso. From the front, draw a horizontal line across the chest at about nipple height, two similar vertical lines through them, and a horizontal line across the bottom of the neck/throat. That is where all the main blood vessels are, and with adequate penetration, the spine is also in there. On the head, it is actually a face shot; a triangle from the bottom of the nose through the outside corners of the eyes. From the side, roughly straight into the ear canal. From the side, you say? Darned right. It is amply foreseeable that one might engaged in an encounter in which the target presented is not straight on; while more likely in LE, it is not impossible in civilian encounters, and one should at least be prepared for the possibility. (Which is one of the reasons for the FBI standard - the torso target area could easily be blocked by an arm or other intermediate barrier.)

Once placement is sound, then there must be adequate penetration. The example of the deer and oxygenated blood applies to people, too. While few are as motivated as a wild animal, if one looks at the detailed reports about the 1986 FBI firefight near Miami that started this research, the will to fight in the offenders kept them going with fatal wounds for long enough to kill or cripple several agents.

Handgun rounds suck. One needs to be able to shoot until the assailant is perceived to no longer present a threat. This might be one round, or as many as 10 or more. Caliber is not that big a factor in performance, if it is at all. Training to perform to the necessary level is, and among the typical semi-auto service calibers, the 9mm is so much cheaper that smart agencies that care about training are moving to it.

In .38, I have gone old school - standard velocity SWC. Same with .41. In auto-pistol calibers, regardless of the platform from which it is launched, one of the rounds recommended by Dr. Roberts. I would not carry or allow anything that is round nose - that is simply ill-advised to the point of stupid with possible exception of .380. If I really expect a problem and can't be elsewhere, the answer is a long gun. Slugs in 12 gauge, or one of the proven runs in 5.56X45. I do not buy 3rd tier firearms or ammo - I buy proven quality (BCM ARs, Glock pistols, S&W Revolvers; Black Hills ammo for most uses, and a lot of it at a time.) I don't waste money on a new car (my 163K Subaru runs fine and has been paid off for over 5 years), a boat, golf, or other counterproductive silliness. I hopefully will never need the gear I buy, but as a cop and now retired, it is either pointless or priceless - there is no in-between.
 
Some YouTube star posts a video talking about no such thing as knock down power and everyone believes him,jeeze luis.
The logic used is that they try to say that the handgun would knock you down when you shoot it , if it had enough force to knock down what you are shooting.
And that is totally an incorrect statement! Percieved recoil is about 1/8 ( depending on the firearm) . So a .45 acp delivering 850 ft lbs to your target is only projecting less than 50 ft lbs to the shooter.
Now go to your garage and grab a torque wrench and torque a bolt to 850 ft lbs. Yep, you will need your neighbors to come help, even with a 4ft cheater bar. When your done, come back and post how 850 ft lbs is not enough to knock you down.
I'll be waiting!

But people routinely get shot with .45ACP rounds and not only don't get knocked down, continue to fight
 
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