# 9mm, 40 S&W, or 45 acp?



## HogHunter (Mar 13, 2018)

Let's look at these three cartridges and some numbers that are not in the ballistic charts, but are available and maybe important to you. I am not going to look at a lot of different cartridges weights or manufacturers. I am just going to pick one cartridge that is a good representative for each cartridge. 

9mm - Federal 124 gr; bullet velocity of 1120 f/s; energy of 345 ft/lbs; recoil of 5 lbs; knock down coefficient 7
40 SW - Federal 180 gr; bullet velocity of 990 f/s; energy of 390 ft/lbs; recoil of 7 lbs; knock down coefficient 10
45 acp - Federal 230 gr; bullet velocity of 850 f/s; energy of 370 ft/lbs; recoil of 7 lbs; knock down coefficient 13

The 9mm handgun used to figure recoil was a Glock 19 which holds 16 rounds. The 40 SW handgun used to figure recoil was a Glock 23 which holds 14 rounds. The 45 acp handgun used to figure recoil was a Colt lightweight commander which holds 9 rounds. The formulas used to figure recoil and knock down coefficient are found on Beartooth Bullets' website.

The knock down coefficient is a measure of a cartridges ability to knock a person down. This is important when shooting a person on drugs. The knock down coefficient is sometimes called Taylor Knock Out Power. 

The 9mm's advantage is: It holds the most cartridges and has the lowest recoil. The 45 acp's advantage is: It has the highest knock down coefficient. The 40 SW appears to be a compromise between higher cartridge capacity and knock down coefficient.


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## LostinTexas (Oct 1, 2018)




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## Steve M1911A1 (Feb 6, 2008)

HogHunter said:


> ...The knock down coefficient is a measure of a cartridges ability to knock a person down. This is important when shooting a person on drugs. The knock down coefficient is sometimes called Taylor Knock Out Power...


If I properly understand all of the conversations I've had with LEOs and ex-military personnel, I suggest to you that "knock down power" and "knock out power" are myths.

There is no handgun cartridge which will reliably knock anyone down.
If there were such a cartridge, it would also "knock down" the shooter. See _Newton's Third Law_: Every action has an equal but opposite reaction.

While the .45 ACP cartridge has always been a reliable fight stopper, particularly after the shooter has made multiple _accurate_ hits, other cartridges using appropriate modern bullets in the same manner will have the very same effect.
On the other hand, European police agencies successfully used the .32 ACP (7.65x17mm) cartridge for many, many years to do the very same work.

The biggest difference was to be found in the attitude of the recipients of the bullets fired.
The European criminal hit by a single 7.65mm bullet would concede that "the game was up," and would immediately surrender in order to receive medical attention, while the American criminal would react by attacking the person who had shot him.
(All that has changed nowadays: Everybody now fights back.)

It isn't the cartridge.
It's the accurate shot placement.
And there is no "knock down."


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## SamBond (Aug 30, 2016)

_Knock Down_ _Power _... That's why there is a 340 Wheatherby Magnum in my holster.


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## HogHunter (Mar 13, 2018)

I am not suggesting any particular caliber. When I am carrying inside the belt, I pick the 1911 because the holster is more comfortable. When I carry outside the belt, I pick the Glock 19 (9mm) or the Glock 23 (40 caliber). If I am in a hurry, I pick a 380 pocket pistol.

As far as knock down power, the 45 acp was designed specifically for the military and adopted by the military for it's ability to knock people down. And it did a very good job through WWI, WWII, Korean conflict, and Vietnam conflict. Some people say there is no such thing as knock down power and you sited Sir Issac Newton's third law of motion. But is not recoil more in a 45 acp than a 9mm. The 45 handgun was also heavier than the 9mm handgun. If the two handguns had been the same weight, the 45 acp handgun would have had even more recoil. And is not recoil the offsetting force for firing a bigger and heavier bullet. And does not a bigger and heavier bullet have more impact force than a lighter, smaller diameter bullet. There is not such thing as knock down force (impact force), I do not agree. But this is America and everyone is entitled to their own opinion. I am not trying to make you mad, I just have a different opinion.


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## Steve M1911A1 (Feb 6, 2008)

Recoil Note:
The recoil of a full-size, full-weight .45 ACP M1911 is so soft and controllable that my _very _petite wife learned pistol shooting with it exclusively (with 230-grain bullets at 900fps).
Also, I know from experience that any reasonably strong 10-year-old child can be taught to shoot the M1911 successfully.


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## Tangof (Jan 26, 2014)

Felt recoil differs from measured recoil, at lest that is my experience. When testing various handguns for Federal LEO use, every Officer, Male and Female, said the Colt Series 70 at 35.02 ounces, recoiled more in their hand than the 29.54 Oz. Glock 21. Ammunition was 230 Grain FMJ. The CZ97b, 36.02 ounces, personal experience, is the softest shooter of the three.


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## Steve M1911A1 (Feb 6, 2008)

HogHunter said:


> ...is not recoil more in a 45 acp than a 9mm...


It's not a matter of "more," but rather one of "different."

First of all, recoil is a function of _both_ bullet mass _and_ bullet velocity. Therefore, a slow-moving .45 bullet may cause less recoil (both measured and felt) than a fast-moving 9mm bullet.

Second, generally speaking, the recoil of the standard-hardball .45 ACP cartridge in a full-size, full-weight pistol like the M1911 is experienced as a slow push, which, with sufficient preparation and practice, is easily controlled by almost anyone.
On the other hand, many standard-hardball 9mm loadings (particularly those loaded to properly function in a Luger) generate recoil which might be characterized as a quick jab or shove. These loads are harder to control than are standard-hardball .45 loads, especially when fired from a "plastic fantastic," lightweight pistol.


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## SamBond (Aug 30, 2016)

*"There is not such thing as knock down force (impact force), I do not agree."* - Hog quote

Sure there is such a thing as _Knock Down Power, _ but the 45 ACP does not have enough of it to knock 'em down. 
I understand it is a powerful stopper and can make 'em fall, but for real _Knock Down_ .... 340 Weatherby.


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## HogHunter (Mar 13, 2018)

I am sorry that I made some of you mad, but we are talking about physics. A object in motion (be it a baseball, car, or bullet) will impart an impact force on a stationary object. The impact force can be calculated. In the case of bullets, scientist gave us a formula to figure the impact force. The main components are bullet diameter, weight, and impact velocity and they called it knock down power (sometimes called Taylor Knock Out Power). It is real.


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## Steve M1911A1 (Feb 6, 2008)

Ain't nobody mad at nobody.
It's just that we've had this discussion before. Seemingly endlessly.

We're all beating dead horses.
Let's stop.


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## Tangof (Jan 26, 2014)

Steve M1911A1 said:


> Ain't nobody mad at nobody.
> It's just that we've had this discussion before. Seemingly endlessly.
> 
> We're all beating dead horses.
> Let's stop.


 I concur. The cartidge war's are seemingly endless and don't solve anything. I remember my two Great Uncles arguing the stopping power of the S&W .32 Long as opposed oi the .32 Colt New Police.


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## tony pasley (May 6, 2006)

The best handgun is the one you can put the bullets into the target. The best caliber is the one in the target 
Steve quit beating those horses


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## SamBond (Aug 30, 2016)

HogHunter said:


> I am sorry that I made some of you mad, but we are talking about physics. A object in motion (be it a baseball, car, or bullet) will impart an impact force on a stationary object. The impact force can be calculated. In the case of bullets, scientist gave us a formula to figure the impact force. The main components are bullet diameter, weight, and impact velocity and they called it knock down power (sometimes called Taylor Knock Out Power). It is real.


Possibly we're just using different terminology here, splitting hairs some might say.
It's all good. Don't think anybody's mad...


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## Goldwing (Nov 5, 2014)

I had the privilege of talking to a friend of my older brother on this subject. He was a former Israeli Mossad operator. At the time I was of the opinion that a .45 ACP was the best medicine to stop a fight.

His opinion was that it is preferable to use a 9mm and apply a double tap to the chest and a head shot as the bad guy was reeling from the double tap. It seemed reasonable to me.

GW


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## berettatoter (Sep 1, 2011)

I wouldn't want to get shot by a BB, let alone ANY bullet.


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## Steve M1911A1 (Feb 6, 2008)

Goldwing said:


> I had the privilege of talking to a friend of my older brother on this subject. He was a former Israeli Mossad operator. At the time I was of the opinion that a .45 ACP was the best medicine to stop a fight.
> 
> His opinion was that it is preferable to use a 9mm and apply a double tap to the chest and a head shot as the bad guy was reeling from the double tap. It seemed reasonable to me.
> 
> GW


Either. Or. Doesn't matter.
The main point made by your brother's friend is that _accurately-placed hits are what does the job_.

For instance, head shots are hard enough to make if the target is stationary.
They require tremendous skill when the target is moving...even just a little bit.

If you can make reliable head shots on a slightly-moving target at 10 yards, it really doesn't matter what (centerfire) cartridge you do it with. Any such hit is a fight-stopper.


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## paratrooper (Feb 1, 2012)

That seems to be awfully cruel. Beating a dead horse I mean. Who in their right mind does that? 

The damn thing is dead. What's the purpose?


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## Steve M1911A1 (Feb 6, 2008)

Evidently you've never metaphor you didn't like.


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## Tangof (Jan 26, 2014)

I've never met a phor. Small animal? What's the proper gun/caliber?


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## Goldwing (Nov 5, 2014)

Steve M1911A1 said:


> Evidently you've never metaphor you didn't like.


I have met a "Phor" and it told me that, and I quote," You can lead a horticulture, but you can't make her think"

Too much??

GW


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## TheReaper (Nov 14, 2008)

Steve M1911A1 said:


> *Ain't nobody mad at nobody*.
> It's just that we've had this discussion before. Seemingly endlessly.


You sure don't sound like you're from the Northwest ?

I prefer the Taurus in " D " cell caliber.


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## Steve M1911A1 (Feb 6, 2008)

Tangof said:


> I've never met a phor. Small animal? What's the proper gun/caliber?


The proper hunting tool is a piece of iron-y.


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## Steve M1911A1 (Feb 6, 2008)

TheReaper said:


> You sure don't sound like you're from the Northwest ?


Nope.
I'm from Noo Yawk...by way of Lost Angels.
But now I live at the far upper left-hand corner of the US.


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## BackyardCowboy (Aug 27, 2014)

Steve M1911A1 said:


> Nope.
> I'm from Noo Yawk...by way of Lost Angels.
> But now I live at the far upper left-hand corner of the <Continental> US.


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## Steve M1911A1 (Feb 6, 2008)

Darn literalist!

"Continental" still isn't right: Alaska's still on the North American Continent, as far as I know. (Although since that last big 'quake, maybe not.)

How 'bout "contiguous," instead?


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## hillman (Jul 27, 2014)

Tangof said:


> I've never met a phor. Small animal? What's the proper gun/caliber?


We should settle this. 'Phor' is a phonetic rendition of '4'. As used in this environment, it is 4 in the well-known 10 point rating system. I have always believed that the actress so rated was really an 8.5.


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## paratrooper (Feb 1, 2012)

TheReaper said:


> You sure don't sound like you're from the Northwest ?
> 
> I prefer the Taurus in " D " cell caliber.
> View attachment 16786


Kel-Lif=ght


TheReaper said:


> You sure don't sound like you're from the Northwest ?
> 
> I prefer the Taurus in " D " cell caliber.
> View attachment 16786


Way, way back in my early days, I carried one of these. 7 D-Cell KEL Light.


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## Steve M1911A1 (Feb 6, 2008)

hillman said:


> ...'Phor' is a phonetic rendition of '4'. As used in this environment, it is 4 in the well-known 10 point rating system...


Well, OK...
We seem to have a phor-point buck who eats the squirrel corn we put out.
Next season, maybe one of our neighbors will eat him, instead.



hillman said:


> I have always believed that the actress so rated was really an 8.5.


If it was Marilyn, I think I'd go higher than that.
But she was already absorbing culture (if only "down there"), having married Arthur Miller.


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## BackyardCowboy (Aug 27, 2014)

Steve M1911A1 said:


> Darn literalist!
> 
> "Continental" still isn't right: Alaska's still on the North American Continent, as far as I know. (Although since that last big 'quake, maybe not.)
> 
> How 'bout "contiguous," instead?


More like "Contentious"


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## Steve M1911A1 (Feb 6, 2008)

BackyardCowboy said:


> More like "Contentious"


Only if they're Blue.


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## andymidplains (Nov 30, 2012)

HogHunter said:


> I am sorry that I made some of you mad, but we are talking about physics. A object in motion (be it a baseball, car, or bullet) will impart an impact force on a stationary object. The impact force can be calculated. In the case of bullets, scientist gave us a formula to figure the impact force. The main components are bullet diameter, weight, and impact velocity and they called it knock down power (sometimes called Taylor Knock Out Power). It is real.


An object in motion does not impart a consistent impact force on an object that it passes through; therefore, the concept of "knockdown power", as defined above, is precise but of little practical value.


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## SamBond (Aug 30, 2016)

Tangof said:


> I've never met a phor. Small animal? What's the proper gun/caliber?


A 10 ga shotgun loaded with 000B. Phors are some tough critters. 

Sam


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## Philco (Apr 17, 2012)

Tangof said:


> I've never met a phor. Small animal? What's the proper gun/caliber?


Most phor hunters prefer handgun hunting with 9mm, .40 cal, or .45ACP. Each cartridge has its merits, but to knock down a full grown phor you'll need excellent shot placement to the phor head.


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## Goldwing (Nov 5, 2014)

Since the Phor has male pattern baldness the Phor head is also commonly referred to as the PHIVE HEAD.

GW


Philco said:


> Most phor hunters prefer handgun hunting with 9mm, .40 cal, or .45ACP. Each cartridge has its merits, but to knock down a full grown phor you'll need excellent shot placement to the phor head.


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## denner12 (Oct 14, 2017)

.40 cal is the real man's caliber, 9mm is for girls and .45 cal is for old men.


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## Steve M1911A1 (Feb 6, 2008)

denner12 said:


> .40 cal is the real man's caliber, 9mm is for girls and .45 cal is for old men.


Nope.
The _.380 ACP_ is for old men.
Ask me how I know.

The .45 ACP is for middle-age connoisseurs.
(That's what I once was.)


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## Tangof (Jan 26, 2014)

Are we still arguing caliber's? I fell asleep.


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## Steve M1911A1 (Feb 6, 2008)

We are not _arguing_.
We are merely _discussing_.

We can keep it a friendly discussion because, gentleman that I am, I refrain from telling everybody else how wrong they are.


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## Tangof (Jan 26, 2014)

Since we're discussing, I think the best answer is to own something in all three calibers. This way, no matter what, you can strongly DISCUSS your point of view.


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## Steve M1911A1 (Feb 6, 2008)

Tangof said:


> Since we're discussing, I think the best answer is to own something in all three calibers. This way, no matter what, you can strongly DISCUSS your point of view.


Three barrels, three magazines, one trigger?

Hmmm... Recoil must be fierce.


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## Tangof (Jan 26, 2014)

Recoil is stout, but manageable with the proper grip. When my cast comes off I'll prove it can be done.


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