Compare 9mm, 40 S&W and 45 ACP in Self-Defense Shooting?

[Frank Ettin]

...Momentum is a better way to measure the transfer to a target takes place......

Irrelevant. At handgun velocities energy transfer is meaningless.

There is data, and there are studies, and we have a good deal of knowledge about wound physiology. What all that shows with regard to self defense could be summarized as follows:

1. Pretty much every cartridge ever made has at times succeeded at quickly stopping an assailant.
   
   
2. Pretty much every cartridge ever made has at times failed at quickly stopping an assailant.
   
   
3. Considering ballistic gelatin performance, data available on real world incidents, an understanding of wound physiology and psychology, certain cartridges with certain bullets are more likely to be more effective more of the time.
   
   
4. For defensive use in a handgun the 9mm Luger, .38 Special +P, .40 S&W, .45 ACP, .357 Magnum, and other, similar cartridges when of high quality manufacture, and loaded with expanding bullets appropriately designed for their respective velocities to both expand and penetrate adequately, are reasonably good choices.
   
   
5. And that's probably as good as we can do.

I've posted the following before and might as well post it again here:

Let's consider how shooting someone will actually cause him to stop what he's doing.

• The goal is to stop the assailant.
  
  
• There are four ways in which shooting someone stops him:
  
  
  • psychological -- "I'm shot, it hurts, I don't want to get shot any more."
    
    
  • massive blood loss depriving the muscles and brain of oxygen and thus significantly impairing their ability to function
    
    
  • breaking major skeletal support structures
    
    
  • damaging the central nervous system.
  
  Depending on someone just giving up because he's been shot is iffy. Probably most fights are stopped that way, but some aren't; and there are no guarantees.
  
  Breaking major skeletal structures can quickly impair mobility. But if the assailant has a gun, he can still shoot. And it will take a reasonably powerful round to reliably penetrate and break a large bone, like the pelvis.
  
  Hits to the central nervous system are sure and quick, but the CNS presents a small and uncertain target. And sometimes significant penetration will be needed to reach it.
  
  The most common and sure physiological way in which shooting someone stops him is blood loss -- depriving the brain and muscles of oxygen and nutrients, thus impairing the ability of the brain and muscles to function. Blood loss is facilitated by (1) large holes causing tissue damage; (2) getting the holes in the right places to damage major blood vessels or blood bearing organs; and (3) adequate penetration to get those holes into the blood vessels and organs which are fairly deep in the body. The problem is that blood loss takes time. People have continued to fight effectively when gravely, even mortally, wounded. So things that can speed up blood loss, more holes, bigger holes, better placed holes, etc., help.
  
  So as a rule of thumb --
  
  
  • More holes are better than fewer holes.
    
    
  • Larger holes are better than smaller holes.
    
    
  • Holes in the right places are better than holes in the wrong places.
    
    
  • Holes that are deep enough are better than holes that aren't.
    
    
  • There are no magic bullets.
    
    
  • There are no guarantees.
  
  
• With regard to the issue of psychological stops see
  
  
  • this study, entitled "An Alternate Look at Handgun Stopping Power" (yes, the very study referenced by boltomatic) by Greg Ellifritz. And take special notice of his data on failure to incapacitate rates:
    
    
    
    ​
    
    
    As Ellifritz notes in his discussion of his "failure to incapacitate" data (emphasis added):

    ...Take a look at two numbers: the percentage of people who did not stop (no matter how many rounds were fired into them) and the one-shot-stop percentage. The lower caliber rounds (.22, .25, .32) had a failure rate that was roughly double that of the higher caliber rounds. The one-shot-stop percentage (where I considered all hits, anywhere on the body) trended generally higher as the round gets more powerful. This tells us a couple of things...
    
    In a certain (fairly high) percentage of shootings, people stop their aggressive actions after being hit with one round regardless of caliber or shot placement. These people are likely NOT physically incapacitated by the bullet. They just don't want to be shot anymore and give up! Call it a psychological stop if you will. Any bullet or caliber combination will likely yield similar results in those cases. And fortunately for us, there are a lot of these "psychological stops" occurring. The problem we have is when we don't get a psychological stop. If our attacker fights through the pain and continues to victimize us, we might want a round that causes the most damage possible. In essence, we are relying on a "physical stop" rather than a "psychological" one. In order to physically force someone to stop their violent actions we need to either hit him in the Central Nervous System (brain or upper spine) or cause enough bleeding that he becomes unconscious. The more powerful rounds look to be better at doing this....

    
    
    1. There are two sets of data in the Ellifritz study: incapacitation and failure to incapacitate. They present some contradictions.
       
       
       • Considering the physiology of wounding, the data showing high incapacitation rates for light cartridges seems anomalous.
         
         
       • Furthermore, those same light cartridges which show high rates of incapacitation also show high rates of failures to incapacitate. In addition, heavier cartridges which show incapacitation rates comparable to the lighter cartridges nonetheless show lower failure to incapacitate rates.
         
         
       • And note that the failure to incapacitate rates of the 9mm Luger, .40 S&W, .45 ACP, and .44 Magnum were comparable to each other.
         
         
       • If the point of the exercise is to help choose cartridges best suited to self defense application, it would be helpful to resolve those contradictions.
         
         
       • A way to try to resolve those contradictions is to better understand the mechanism(s) by which someone who has been shot is caused to stop what he is doing.
       
       
    2. The two data sets and the apparent contradiction between them (and as Ellifritz wrote) thus strongly suggest that there are two mechanisms by which someone who has been shot will be caused to stop what he is doing.
       
       
       • One mechanism is psychological. This was alluded to by both Ellifritz and FBI agent and firearms instructor Urey Patrick. Sometimes the mere fact of being shot will cause someone to stop. When this is the stopping mechanism, the cartridge used really doesn't matter. One stops because his mind tells him to because he's been shot, not because of the amount of damage the wound has done to his body.
         
         
       • The other mechanism is physiological. If the body suffers sufficient damage, the person will be forced to stop what he is doing because he will be physiologically incapable of continuing. Heavier cartridges with large bullets making bigger holes are more likely to cause more damage to the body than lighter cartridges. Therefore, if the stopping mechanism is physiological, lighter cartridges are more likely to fail to incapacitate.
       
       
    3. And in looking at any population of persons who were shot and therefore stopped what they were doing, we could expect that some stopped for psychological reasons. We could also expect others would not be stopped psychologically and would not stop until they were forced to because their bodies became physiologically incapable of continuing.
       
       
    4. From that perspective, the failure to incapacitate data is probably more important. That essentially tells us that when Plan A (a psychological stop) fails, we must rely on Plan B (a physiological stop) to save our bacon; and a heavier cartridge would have a lower [Plan B] failure rate.
  
  
• Also see the FBI paper entitled "Handgun Wounding Factors and Effectiveness", by Urey W. Patrick. Agent Patrick, for example, notes on page 8:

  ...Psychological factors are probably the most important relative to achieving rapid incapacitation from a gunshot wound to the torso. Awareness of the injury..., fear of injury, fear of death, blood or pain; intimidation by the weapon or the act of being shot; or the simple desire to quit can all lead to rapid incapacitation even from minor wounds. However, psychological factors are also the primary cause of incapacitation failures.
  
  The individual may be unaware of the wound and thus have no stimuli to force a reaction. Strong will, survival instinct, or sheer emotion such as rage or hate can keep a grievously wounded individual fighting....

• And for some more insight into wound physiology and "stopping power":
  
  
  • Dr. V. J. M. DiMaio (DiMaio, V. J. M., M. D., Gunshot Wounds, Elsevier Science Publishing Company, 1987, pg. 42, as quoted in In Defense of Self and Others..., Patrick, Urey W. and Hall, John C., Carolina Academic Press, 2010, pg. 83):

    In the case of low velocity missles, e. g., pistol bullets, the bullet produces a direct path of destruction with very little lateral extension within the surrounding tissue. Only a small temporary cavity is produced. To cause significant injuries to a structure, a pistol bullet must strike that structure directly. The amount of kinetic energy lost in the tissue by a pistol bullet is insufficient to cause the remote injuries produced by a high-velocity rifle bullet.

    
    
  • And further in In Defense of Self and Others... (pp. 83-84, emphasis in original):

    The tissue disruption caused by a handgun bullet is limited to two mechanisms. The first or crush mechanism is the hole that the bullet makes passing through the tissue. The second or stretch mechanism is the temporary wound cavity formed by the tissue being driven outward in a radial direction away from the path of the bullet. Of the two, the crush mechanism is the only handgun wounding mechanism that damages tissue. To cause significant injuries to a structure within the body using a handgun, the bullet must penetrate the structure.

    
    
  • And further in In Defense of Self and Others... (pp. 95-96, emphasis in original):

    Kinetic energy does not wound. Temporary cavity does not wound. The much-discussed "shock" of bullet impact is a fable....The critical element in wounding effectiveness is penetration. The bullet must pass through the large blood-bearing organs and be of sufficient diameter to promote rapid bleeding....Given durable and reliable penetration, the only way to increase bullet effectiveness is to increase the severity of the wound by increasing the size of the hole made by the bullet....

  
  
• And sometimes a .357 Magnum doesn't work all that well. LAPD Officer Stacy Lim who was shot in the chest with a .357 Magnum and still ran down her attacker, returned fire, killed him, survived, and ultimately was able to return to duty. She was off duty and heading home after a softball game and a brief stop at the station to check her work assignment. According to the article I linked to:

  ... The bullet ravaged her upper body when it nicked the lower portion of her heart, damaged her liver, destroyed her spleen, and exited through the center of her back, still with enough energy to penetrate her vehicle door, where it was later found....

 

[Brit]

Frank, I sat in on a lecture by LAPD Officer Stacy Lim, at an IALEFI Annual Training Conference, my impression, her inner strength, will power if you would, drove her to winning that contest against that teen aged thug!

And her surviving, was the fact that the action/gun fight was observed by her room mate, who was a nurse! Called 911, and imparted the right information, in a way that triggered the correct response.

And her own first aid actions right there at the scene. In my mind, a miracle!

Her duty belt was on her shoulder, just being transported into the house, from her vehicle, this house, shared by 2? other Lady's.

I think the pistol was a Beretta 92, 9mm?

 

[ShootistPRS]

Every time I see that report I cringe. The results of that report state that the 357 is the most effective handgun at incapacitating the bad guy; It is as effective as a rifle. According to that study it is more effective than a shotgun.

I carry a 357 and I would like to believe that my 357 is as good as that report states but I have tested the 357, rifles and shotguns and I know that in the hands of a competent shooter any gun can stop a bad guy. I believe the report just shows the competency of the average shooter who owns the gun listed.

People who use a 22 are probably not as practiced as the average 357 owner. Bullet placement is the most important variable in self defense.

 

[OldMarksman]

BLAM! The big-bore gun goes off, and the bad guy is blown back through the saloon doors and into the street. "Energy transfer"? No. Fiction. It is only in fiction where the laws of physics do not apply.

That .45 ACP pistol I rented at the range around seven years ago sure kicked with a lot of authority. There was the famous story of the Moros. And the Thompson-Lagarde tests. And Larry Potterfield spoke about the ability of a gun to "knock down" an assailant.

It had to be effective.

So I bought one.

I had never participated in any advanced defensive pistol training, and I placed far too much importance on terminal ballistics and far too little on rapidity of fire.

Someone here made a comment that has stuck with me. He or she stated that handgun wounding effects are more comparable to the effect of taking a meal poker tithe tapered end and sticking it into someone quickly and with sufficient force to crush tissue, break bone, and penetrate to and into some vital organ or other. No "knock down" involved. No "energy transfer".

A good way to put it.

 

[DMK]

Every time I see that report I cringe. The results of that report state that the 357 is the most effective handgun at incapacitating the bad guy; It is as effective as a rifle. According to that study it is more effective than a shotgun.

One of the big problems with that data is the wide variations in the number of incidents.

You have 456 people shot by 9mm, 105 people shot by 357, 126 people shot by rifles of various calibers and just 25 people shot by 32ACP (with 72% one shot incapacitation).

The odd lucky or unlucky individuals can really skew the results with the smaller numbers of incidents as demonstrated clearly by the 32ACP result.

 

[ShootistPRS]

As you say that is just one of many of the problems with that report.
They also don't account for all the times a bad guy runs at the sight of an armed home owner - no shots fired. The objective skill of the good guy is also left out of the study and that is likely the largest factor. Bullet placement trumps everything else.

 

[BIGR]

Does not surprise me at all about the .357. Whether it be .357 Magnum in a revolver or a .357 Sig in an auto it has proven its effectiveness.

This could be debated from now on.
.38, 9MM, .40, .357 or .45 their all good if you do your part.

 

[Lohman446]

It is my opinion that one buys guns in categories. For pistols

.22 - this is pretty well not interchangeable with anything. You "need" a rimfire pistol

9MM / .38 / .40 / .45 - this is a good defensive round. Depending on your needs you should have one or more of these in a compact or sub compact as a carry pistol and however many others you feel the need for.

10MM / .357 Mag / .41 Mag /.44 Mag - this is the category that is a big pistol but is still useful for carrying in non-hunting applications or as a back-up in hunting applications or home-defense. In fact some of us have carried them as a primary in some hunting situations. A "large" pistol capable of being carried.

.460 / .500 - other more exotics - the "big" gun whose primary purpose is mimicking a rifle for hunting.

Obviously you CAN get away with less. A good .357 revolver, or a G29, can cover both middle categories.

The argument over 9MM, .40, .45 - to me they are all so close in various aspects as to be tactically interchangeable.

 

[Lohman446]

Someone here made a comment that has stuck with me. He or she stated that handgun wounding effects are more comparable to the effect of taking a meal poker tithe tapered end and sticking it into someone quickly and with sufficient force to crush tissue, break bone, and penetrate to and into some vital organ or other. No "knock down" involved. No "energy transfer".

In this conversation in other places I have asked someone to look at a normal #2 pencil. Now lay a normal sharpie next to it. Next to that put a normal highlighter.

Now imagine someone running you through with any one of those 4 or 5 times somewhere on the torso . You can even pick where.

Are you really going to want to continue the fight? And more to the point if the defender is forced into hand to hand combat after it will he or she have improved his odds of winning? Yet somehow when we start talking FMJ .380 and .22s some people have this idea that they are worthless. I think one of the major errors with "gun people" is the assumption that because you are carrying a firearm you will not be forced into hand to hand combat. A competent and determined attacker (even unarmed) may very well live long enough to close distance and do you harm after you have repeatedly mortally wounded him or her. Its not likely but if you are going to be worried about not having the ability to physiologically stop an attacker with your firearm you should be looking into some skills that are not firearm based.

 

[shafter]

The way I look at it is this. Take a 9, 40, and 45 cartridge in your hand and hold it next to your chest. Note that they all move faster than the eye can see and will easily penetrate your flesh. Is it really going to matter much which hollowpoint you get whacked with?

 

[Nanuk]

I primarily carry my S&W model 69 44 magnum loaded with 180 magnum grain JHP's. I carry a Charter Arms Bulldog as a BUG loaded with 200 grn STHP's. I do not worry about needing 100 rounds of ammo. I shoot this gun in IDPA and have faith in my abilities with it.

 

[xnaerughiazk]

always doing my killing as a hunter, I think the killing of such thin skinned mammals such as humans somewhat a lark, mind you their psychological disposition might be nastier than meat on the table and they will invariable will be closer to us than their meat counterparts.

I have always thought penetration and heavier bullets was always the way to go to put meat on the table. Now rarely do you have meat running at you to eat you when out hunting but I'd still stick to that credence, heaviest and largest, plus you'll have a blood trail to follow to the hospital. Should the officials question your story.

 

[OldMarksman]

I have always thought penetration and heavier bullets was always the way to go to put meat on the table.

Good thinking, usually.

Now rarely do you have meat running at you to eat you when out hunting but I'd still stick to that credence, heaviest and largest,...

At some point it's heavy enough and large enough for the human target, and the discriminators become the rate of controlled fire and capacity.

....plus you'll have a blood trail to follow to the hospital. Should the officials question your story.

Best not to joke on serious subjects here.

 

[xnaerughiazk]

A competent and determined attacker (even unarmed) may very well live long enough to close distance and do you harm after you have repeatedly mortally wounded him or her. Its not likely but if you are going to be worried about not having the ability to physiologically stop an attacker with your firearm you should be looking into some skills that are not firearm based.

I have always thought that it is not so much stopping any one if determined, but having them bleed out before they get you

 

[xnaerughiazk]

Best not to joke on serious subjects here.

The shooting of humans is no joke other than surrounded by bands and flags, heard that on the tele, you know the EU stations we are all "whatever now"?

I think that hunters have a damn good idea on Knock down power and it is mostly placement, but it also is caliber.

I know old Markman knows the works of Keith, but would suggest "sixguns" "hell I was there" by Keith. Much to be learned by non-revenuers of the past.

 

[WIN71]

Excellent responce Frank

Very well not only thought out but researched. Facts everywhere. Referenced, studies, the works.
I realize you are a retired attorney that represented Blue Cross but your writing ability and logical thought process is absolutely amazing. Add to that your firearms training. WOW.
You should open a practice defending or assisting CCW's in need. I spent 33 years on the street and I'd work for you.
Absolutely a great post.
Back to the OP. If it happens, shoot fast. Doesn't much matter what you have in your hand.

 

[DMK]

Now imagine someone running you through with any one of those 4 or 5 times somewhere on the torso . You can even pick where.

Are you really going to want to continue the fight?

I have always thought that it is not so much stopping any one if determined, but having them bleed out before they get you

Sometimes people think about these things in the terms of a normal, rational human being. Yes, a rational person does not want to get shot with a 22LR or stabbed with a skewer. They would likely decide that they'd rather stop whatever they are doing and work on being somewhere else ASAP.

The problem is you can't count on that. Someone who is enraged enough to attempt to kill another human over a few dollars or some minor argument or some other imagined reason, may not even feel the pain of getting shot. They may not hear the gun shot (auditory exclusion). If you have not incapacitated them immediately, you may not live long enough for them to bleed out and collapse.

IMO, this is why HP penetration is the more important factor vs bullet diameter. You want both, but you do not want to give up penetration to get that bigger bullet. You ultimately want a round that will expand nice and fat then penetrate deep to hit something very vital.

You also don't want to count on one shot doing the job. You keep shooting until the threat is no longer trying to kill you. So that little 5 round J-frame or 45ACP compact might not be enough, especially with more than one attacker. I'd rather keep rolling that dice as many times as I can with as many rounds as possible. Many holes trumps a few bigger ones.

Then again you may pull your gun and everyone runs away. If you want to bet your life on a statistical average.

 

[Brit]

Stabbed with a Skewer? No, but some deranged young man stabbed me with a home made Ice Pick, in Liverpool UK, in the early 60s.
He aimed for center chest, me stepping back, and went in to a crouch! You always settle into a crouch! No idea why, but you do.

Now this well made stabbing tool has entered my right wrist, and my fingers are wrapped around his left wrist! He tried to pull back (to try again?) it did not end well for him.

But reference deterrent effect to me, as in being stabbed? Nothing, I felt no pain at all. And actually saw the point of entry. My whole focus was in attacking. And because the actual amount of fights I had been in the 5 year period of working on the doors of Clubs in Liverpool I could not count! It was a automatic reflex action.

But reference being attacked in down Town USA, by a Criminal, who might be well versed in this type of attack, possibly more practiced than Joe out on the Town CCW carrier? My advise to other old Guys (me aged 81) wear foot wear that grips well, carry always, limit late night excursions. Escort your Lady into her seat, lock passenger door, prior to you mounting up. English. Old School.

 

[Lohman446]

I think my stance is being mistaken slightly.

A full size steel framed 1911, an SP101, a G19, or an NAA mini revolver one should not be solely dependent on his or her firearm rendering the attacker incapable of continuing the attack. Chances are a competent and determined attacker is going to get to contact distance before being physiologically disabled. Now a handful of holes is likely to render said attacker less capable then he or she was at the beginning of the encounter and should not be entirely dismissed but, in preparation for self defense, one must be prepared for the distinct possibility he or she is going to be forced into fighting at contact distance and that the use of the firearm may be less than the optimal choice - though I will note a full sized 1911 or SP101 probably make wonderful clubs.

 

[Onward Allusion]

Want knock down power? Use a 12 ga w/slugs.

In a SD shooting against 2 leggers, I'd want capacity but with more energy than a 22LR. For me, 9mm & 40S&W fits the bill.