9mm VS .40 VS .45 – The Great Debate Goes On

Let me just say that this article is my own personal commentary on this debate. I’m not trying to bring forward a “be all/end all” conclusion type of article. It’s just my own data points and thoughts. Personally I believe this debate will never end. There will always be biased, myopic people who don’t listen to factual evidence. And there will always be those that make up their own facts to make their personal purchase sound better. This is to those who look at facts and statistics, and search out the best tools to increase their survivability rate.

I may have said this in previous articles, but it’s a rule for me when it comes to tactical/defensive material and data. I stick to what I know. If I can’t prove it, then I can’t camp on it. I’m going to use that as a compass on where to take this article for the most part. I’ll give opinion based on good reason and probable cause but I’ll state when it’s opinion.

“There’s no such thing as a magic bullet. Bullets are designed to hit things. That’s exactly what they do.” – Chris Costa

Chris has is 100% correct. Bullets are designed to hit a target to knock it down. So there is no magic bullet. But there are some that are more effective due to basic physics.

Laws of physics that you need to keep in mind:

  • Adding velocity adds kinetic energy
  • Adding mass increases kinetic energy

We have to find a balance between a few things for an optimal handgun cartridge. Also, we have to determine what purpose that cartridge will serve. I’m focusing on one purpose, and that is getting a “stop right now” bullet. When fired, that bullet when striking below the clavicles and above the belly button should take the enemy down. We need a balance of these features to achieve that.

  • Velocity – Because it must get through thick clothing, windows, wall material, and have the ability to have devastating effects at longer ranges.
  • Kinetic energy – There’s no point in me shooting someone to have them get a little hurt and come back and sue me later. Or worst case scenario; the bullet not phase them and I get killed. The bullet has to have enough knock down power to drop someone when hit in the areas mentioned before.
  • Capacity – Small enough to carry an appropriate amount of rounds in a magazine in a mid-sized sidearm.
  • Manageable recoil – It doesn’t help me at all when after my first shot I’m disoriented and lost a good grip, muzzle alignment etc…

9mm – Small bullet, high-capacity

The 9mm cartridge is of German origin. It was designed to fit and feed reliably in the Luger 9mm pistol in 1902. The thought was that the bullet would feed reliably, not have effective knock down power. It was also made in its size because less lead, brass, powder, and copper equals less money. During WW2 the Germans were even known for mixing iron and lead because they were so low on the material.

One of the most widely used loads for a 9mm is the Speer Gold Dot 124 gr. It has 410 lbs of energy at 1,220 fps.

Highest energy load you can get with 9mm is an RBCD load that carries about 500 lbs of kinetic energy. That’s something I’d be comfortable with.


  • Low recoil
  • High capacity in most cases
  • Lower cost
  • Travels a good distance before significant bullet drop

My personal choice is not 9mm. Between capacity and cost it’s the choice for those categories.


  • Low kinetic energy
  • Lacking in general knock down power due to size and weight ( mass )

Will a 9mm kill someone? Yes, absolutely. But the problem is you either have to shoot them 10+ times, or hit a heart, brain, or spine directly to stop your aggressor immediately in a majority of cases. This is where I may sound biased but I’m not. I look at the data and decide. My first pistol was a Glock 17, and if that’s what I had I’d train into effectiveness with it and trust it more than a pocket knife. But being a fireman I’ve seen 9mm bullet wounds, but never anything like a .40, .45, .357 mag, .44 mag etc… I’ve seen one .40 caliber wound and it was on a corpse.

This guy in the video is having his friend shoot him at point-blank range with a 9mm. The bullet goes into his chest 1″ from his heart ( if you don’t believe that watch this interview where he says in his own words the bullet was 1″ from his heart ) and most likely went out of his back into the bullet proof vest. If it didn’t, it may have gone through the bullet proof vest in the front initially and been slowed enough to stop inside him. In that case it should have added a ton of kinetic energy right? No. Mass is the factor in 9mm. It’s a little bullet. It may take someone out of a fight and I emphasize may but it’s not a “stop right now” bullet from the ballistics and first hand experience of many accounts. If you’ll take notice in the video, he gets shot and doesn’t even fall down. He walks around for a minute and then says “Hang ten” ( roughly translated – ‘I’m ok’ ). Long story short, the guy is fine. It’s like it never happened.

Second story is someone that anyone knows about. I hate to use such a stupid example but 50 cent the rapper. He was shot 9 times, two of those being point-blank head shots. All by a 9mm. He is 100% fine.

And lastly, I heard a story of a little girl in California who was in the crossfire of a drive by shooting when she was 9 years old. She was shot 12 times by fully automatic gunfire ( in 9mm ) and survived. She’s actually in college on a scholarship for soccer. From what I understand she never even lost consciousness during the event until they had to operate on her.

Now I couple that with the reality that lots of people have been killed with 9mm. In some cases when shots are fired the attacker may run, or when struck just fall down and bleed out for 30 minutes. So is a 9mm better than .25 caliber? For sure. But we want 1 or 2 bullets and they’re done. Why? Because we need to adapt to the battlefield:

Statistically attacks happen with 3-6 people since 1998. And %70 of those turn violent ( no matter if it’s a robbery, burglary, etc.. Most events end in serious injury and death ). So if you are unlucky enough to be a victim of one of these attacks then you probably don’t want to have to shoot each guy either perfectly accurate in the heart/brain/spine, or 5-10 times each do you? You may be starting to understand why I don’t carry 9mm to defend my ( or anyone else ) life.

Many military units use 9mm, but they also use 5.56. NATO and political correctness has a hand in that. You can read the story of “Black Hawk Down” and almost all of the service men had something to say about the fact that they had to shoot the militia several times just to get them to stop coming. Randy Shughart carried a 1911 .45 ACP and an M14 ( .308 ) in that conflict and in his final moments defending one of the crash sites was noted to have killed as many as 20 men with single shots ( can’t confirm that but heard from a reliable source ).

So just know this isn’t a “hate on 9mm” moment. I just have to be honest with you, and with myself in understand the facts, then make my decision; not the other way around. If you carry 9mm, I don’t hate on you for it. I’d say “thanks for carrying brother”. But I think you may say the same thing if you ran into someone carrying a .22 caliber 7 shot pistol. That’s where I come from.

.40 Caliber – Mid Ground Punch

The .40 caliber cartridge was designed after the 1986 F.B.I. Miami shootout between them and two serial bank robbers. After that gunfight the F.B.I. ( at the time using .38 revolvers ) realized they were behind the times and need more firepower and a better platform. They started testing on the 9mm, 10mm, and .45 ACP cartridges. Among the three they liked the ammo capacity and awesome stopping power of the 10mm but the recoil was unmanageable with the shooting techniques of that time. The F.B.I. contacted Smith and Wesson and Winchester to develop a shorter 10mm that could be retrofitted into standard frame handguns. Thus in 1990 came the .40 caliber cartridge. The .40 was created specifically to stop the enemy while retaining high ammo capacity. In 87% of all handgun designs the .40 in most magazines only holds 1 to 2 less rounds than the 9mm does. For getting a 1 shot “stop right now” bullet in a huge majority of cases that’s not bad.

A very popular load in the .40 is the Hornady Critical Defense FTX. A 165 gr bullet traveling 1,100 fps lets off 510 lbs of energy and also causes Hydrostatic shock.

( Hydrostatic Shock – A theory that a penetrating projectile can produce remote wounding and incapacitating effects in living targets through a hydraulic effect in their liquid-filled tissues, in addition to local effects in tissue caused by direct impact. “…liquids are put in motion by ‘shock waves’ or hydraulic effects… with liquid filled tissues, the effects and destruction of tissues extend in all directions far beyond the wound axis.” – Frank Chamberlin WW2 Trauma Surgeon/Ballistics Research. Basically when a bullet with energy between 500 and 900 lbs strikes a person above the belly button, their brain is slammed with pressure and kills them or incapacitates them instantly. 9mm, .380, .22 in 95% of cases does not carry this effect. )


  • High capacity ( usually only 1 round less than 9mm )
  • High kinetic energy ( 500-600 lbs of energy on average )
  • High velocity ( same fps as 9mm – in the 1,000 ranges )
  • Manageable recoil
  • Good range
  • Affordable ( usually only $2 more per box than 9mm )

I carry a Glock 23 .40 concealed, and in teaching. People have branded the .40 as “unreliable” and “snappy”. This isn’t so; my Glock has over 6,000 rounds through it, with the recoil spring just getting changed at 5,500. I’ve only ever had 2 malfunctions. Both were stove pipes which are almost always user error. It’s been 99.999% reliable. And snappy means you don’t know how to fire a weapon frankly. I reload my own .40 and I know that standard loads are not loaded that hot at all. It’s a myth.


  • A bit more expensive to shoot ( especially JHP )
  • A little less capacity than 9mm

There’s not much I complain about with .40. It’s an extremely balanced cartridge between velocity, energy on target, capacity, and affordability. I hardly consider recoil a factor in this debate in the case of .40. I can easily shoot semi-rapid fire with one hand quite accurately. It’s not “snappy” as everyone says. Now if you’re used to using a bad grip and not gripping the weapon with any force then you won’t like it. In that case use a .32 caliber. But if you want a fighting weapon that shoots stopping bullets – get a .40. But don’t take it from me. Look at the hard evidence for yourself.

Agencies that use .40 – FBI, DEA, ATF, DHS, NSA, DOD, U.S. Marshall’s, 75% of LEO agencies in the U.S. just to name a few. Why? Stopping power, good recoil, ammo capacity. I’m sorry guys, you can’t refute those facts.

.45 Caliber – The power house

The .45 ACP cartridge was design by John Moses Browning for the M1911 Semi Auto Pistol. It was intended to be an answer to the U.S. Army’s request for two specific things; a pistol that was self-loading, and that had stopping power. At the time the Philippine-American war was going on and the Army with their .38 caliber Colt Single Action Army wasn’t cutting it. They had to shoot the Moro 2 and 3 times and they were still fighting effectively. So John Browning designed the .45 ACP 200 gr cartridge. The Army took the weapon and tested it and said the 200 gr bullet wasn’t big enough, so he added 30 grains. Hence, the .45 ACP 230 grain cartridge was born. It was extremely effective. Just the FMJ cartridge without a special load produced single shot stopping power almost every time. Why? The perfect balance of mass and velocity. Big bullet going fast enough to get about 12 inches of penetration. With it came a permanent wound cavity upon impact of almost 4″. That crushes everything within 4″ and on top of that puts such a shock load on the brain that you’d be a super hero to stay conscious.

Anything you shoot in .45 ACP will produce at least 400 lbs of energy. But a popular load is the Corbon Power Ball coming in at 550 lbs at 1225 fps.

A really powerful load comes from RBCD going 2000 fps, throwing a 90 gr bullet, gives 878 lbs of force. WOW!


  • Usually low velocity, but because of the 230 grain mass ( or lighter bullets going faster ) = one shot stop.
  • Low penetration with lighter loads

The .45 ACP is an amazing cartridge. It’s just so devastating. And with today’s modern cartridges it’s that much more. With a 165 grain bullet going 2,000 fps you get about 6″ of penetration with 700-800 lbs of force being transferred into your target. If you didn’t figure that out; you don’t live through that.


  • Low ammo capacity ( without getting a massive weapon )
  • High cost

I don’t carry a .45 ACP on me often. As much as I love the fact that I can count on one bullet finishing the fight, I can’t count on hitting each aggressor ( if there are several ). I may need to give suppressive fire, or maybe shoot and scoot. If I have an 8 round mag, I may empty 50% of my ammunition ( my life juice ) before I ever engage. The .45 is still a fantastic option though. LEO still uses .45 ACP usually in the Glock 21 – 14 round capacity. In that case it can make a great truck gun, house gun etc… It would just be uncomfortable to carry. Another option would be what I do 70% of the time. I use a Maxpedition Versipack and I keep all my daily stuff in there. I’ll carry it from home, to my security post, to the fire station etc.. And I can keep a full-sized high-capacity pistol with 2 extra mags in there very easily.

The Verdict

At this point, I’m hoping you learned something new. But here’s the point; You have to pick which of these fits your requirements. If your agency doesn’t allow big boy bullets, then it sounds like 9mm is your choice and you need to train into that. If your agency carries .40, train into that. You have to learn your bullets capabilities and learn to utilize it effectively.

If you carry a 9mm and think that bullet is the only thing you want to carry, but you wish it had more knock down power, and maybe you don’t like a .45 because of loss of capacity, and you just hate .40 because it’s the Hatfield to your McCoy then here’s an option:

.357 Sig – The Debate Breaker

I have never owned a .357 Sig chambered weapon. I have shot them several times with I don’t carry and for one reason: Penetration, and almost 18″ of it in some cases. But other than that, listen to this.The .357 Sig is a 9mm bullet in a .40 caliber necked down casing. It has the ammo capacity of .40, with the knock down power of a .45, while shooting a 9mm bullet at very high speeds.

A great load in .357 Sig is the Corbon JHP. The 100 grain bullet carries 568 lbs of force at 1600 fps.


  • Huge knock down power
  • Deep penetration ( unless using a super lightweight bullet going hot )
  • High ammo capacity

The .357 Sig is a devastating round. When you put a light bullet ( say 90 grain ) and load the bullet into a +P category that thing will stop whatever you shoot. It’s the best of all the cartridges! But as with anything, there are a few down sides.


  • Very high cost
  • Semi hot recoil
  • Hard to find ammo

Here’s what I’d do to solve these “Cons”. With most pistols ( especially Glock ) you can buy a .40 cal pistol and a .357 Sig barrel and just swap them out. They take the same magazines. So you can train with .40, and carry your .357 Sig. There are ways around the issues.

The Point

Don’t be myopic! Just because you could only afford a 9mm, don’t say it works just as well as everything else. That’s a scientifically impossible and a lie. If you carry a .45, don’t trash the 9mm because remember the Costa rule! “Bullets are made to hit things”. I’m not advocating being politically correct. My point is: Carry what works. Be realistic. Don’t look at facts and then make up your own fictional statistics on the matter.

Here’s a chart so you can see what I’m talking about with the differences in behavior with different cartridges.


6 thoughts on “9mm VS .40 VS .45 – The Great Debate Goes On

  1. great article you wrote here. I have had firearms since ive been 10 years old but never really had a use for a handgun,(until recent events). I am looking for a good gun to carry concealed on a regular basis. Im pretty sure im going to go with the glock 27 not sure what im going to get my wife yet. Im just not sure if the glock 27 might be to small to grip. thanks for the info im also a firefighter just south of boston

    • Thanks brother (some of us in TTI are firemen as well) – Appreciate your service.

      I highly recommend the Glock 27. Fantastic weapon. Super reliable, great cartridge, good good good. I WOULD however recommend you get the Pierce Grip Extensions. That will fill the grip out to where it feels like you’re holding a Glock 23. The barrel length has nothing to do with the weapons accuracy. It’s really you that will enable that weapon to fly. Sight radius might be it’s only downfall. But I’ve owned a Glock 27 and it’s awesome.

      And my wife carried a Glock 27 just fine. Great weapon for anyone to carry. Thanks for the comment!

  2. There’s a lot of good info in here but you refer to knockdown power multiple times. The FBI has spoken at length on this topic and there is no such thing. The amount of force exerted against a target will never be more than the recoil of the weapon itself. Modern semi-auto pistols in normal calibers such as 9mm, .40S&W, or .45ACP, do not have knockdown strength.

    • It’s a way to describe the cartridges relative effectiveness. Even family of mine kicking doors in overseas, LEO, and friends who have served use these terms. It’s not literal power from an object measured in grains to knock someone over. Let’s not get ridiculous now. If you want to start pulling out microscopes and scalpels then we can, but it would be counter-productive.

  3. Agree with article, exept i own 45, 357 sig & 9mm, and 10mm which is easily the best 10mm & 357 mag are the two badasses of the common calibers. 357 sig however is good, but not on par with 45, its maybe a littl we better than 9 but thats all, id say 40 would be better, never owned a 40 tho, but the 357 sig is loud, its fast, but its still only a 9mm bullet going a bit faster, it has nowhere near the punch and force of a 45. I like it, its somethin different, but 45 and 10 milli is where its at, if ya want 357 get the magnum, waay better. Peace.

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