Caliber Wars – 9mm vs 45 ACP: Who Wins?

Welcome to “Caliber Wars”, a series devoted to talking about the myths, legends and just plain disinformation propagated in the gun community. No, no, no… We are not starting flame wars here! We are trying to (but surely will fail) put those theological discussions to bed (forever). In this article, we will cover the ever-present “which is better, the 9mm or 45 ACP”.


So Gun and Gear Guy, why do you want to start this caliber war? Simple is the answer, Skywalker…

I don’t.

Side by Side – 45 ACP (left), 9mm (right)
This is what we are warring over!

I want to bring to light the ridiculous nature of catering to this discussion over, and over, and over, and over, and over, and over…

Specifically, this article came from a question I answered awhile back. After answering this question in person dozens of times (and I hate to admit, but asked and contemplated this answer personally) and then spending the time answering it (in writing) in my Quora answer, I realized we really have to stop this insanity.

This question presents itself in many ways:

  • Which has more stopping power, the 9mm or 45 ACP?
  • What is the best gun to carry to protect myself, the 9mm or 45 ACP?
  • Does a 9mm have enough stopping power?
  • Is the 45 ACP too much gun for the normal shooter to carry?

And on and on…, the question gets asked. It is a caliber war, plain and simple. People are looking for the final “solution” answer to the age-old question: whose house is nicer; whose car is faster; whose junk is bigger – it is nothing but the promulgation of keeping up with the Joneses.

Hang on, hang on… Why is the 40 S&W, or .380 or… left out? Well, really the 9mm and 45 ACP are the only calibers to consider.

Defensive Caliber Choices

Defensive Caliber Choices (left to right):
38 Special
357 Magnum
9×19 (9mm)
40 S&W
45 ACP

You see this is at the core of the issue. Why is the discussion always and only restricted to these two calibers? Ballistically, a 40 S&W is superior to the 9mm. If you question that, then try to make a 9mm meet the power factor for competition. It is hard. It is simple with a 40 S&W.

Caliber Discussions

Before we get into why this is such an intolerable “Caliber War”, let’s first discuss each caliber in a bit of detail.


The 9x19mm parabellum is the formal specification of the 9mm. It is also known as the 9mm NATO or 9mm Luger. According to many sources this caliber is the most popular pistol cartridge in the world. The original design and cartridge was developed in 1898. While British and American forces ran trials on this caliber as early as 1908, it was Germany’s usage of it during WWII that brought it to prominence. Post WWII many law enforcement, military and paramilitary agencies, wanting to adopt semi-automatic pistols and rifles used the proven designs from Germany.

Aftermath of FBI Miami Shootout

America chose the 45 ACP and the legendary 1911 as the bigger caliber and semi-automatic footprint for military pistols. It was not until the 1980’s and 90’s when many law enforcement agencies adopted S&W Model 39.  At the same time, the military adopted the 9mm M9 (Beretta 92 series) and 9mm pistols rose in usage in the U.S. Some of this adoption and growth was squelched after the FBI shootout in Miami where their officers were vastly out-gunned.

From this, the FBI began to evolve and move to the 40 S&W. Many law enforcement agencies followed suit.

The growth of cheap, striker fire pistols that were coming from the lineage of the Glock 17, created a tsunami of adoption of the 9mm in the late 90’s and on.

The 9mm can fire 115 gr – 150 gr (and a few higher weight) bullets at speeds ranging from 1200 fps to 1400 fps. Many shooting authorities still (generally) viewed the 9mm round as an underpowered caliber for self-defense or tactical usage. While it provided high quantity loading at a light weight and light recoil, many tacticians viewed it as a far lessor and even a dangerous choice.

The WoT (War on Terror) changed all of that. The completely variable environments of the WoT forced bullet manufacturers to literally engage rocket scientists. This radically advanced “bullet technologies” over the last 10 years. Today there are bullets in many calibers (including the 9mm) that can provide controlled expansion of bullets, radical expansion of bullets and other variations that have changed the tables completely on how everyone should view any caliber. No longer are the big bores the sole owners of large wound channels.

An average 115 grain 9mm bullet can penetrate 16″ and has an average expansion size pushing .55″. An average 124 grain bullet can penetrate 18″ and has an average expansion size pushing .61″. That is about the size a 45 ACP ball ammo deforms to – lock, stock and 2 smoking barrels!

45 ACP

John M Browning – Gun Genius

What needs to be said about the 45 ACP? Various 45 caliber rounds have been around for centuries. The 45 Long Colt was one of the infamous guns that “won the West”. The 45 ACP (Automatic Colt Pistol) or 45 Auto (as it is also known) was a cartridge designed by John Browning in 1905 for the Colt semi-automatic pistol. The U.S. Military adopted it after fighting terrorists in the Philippines in the 1910’s who would not stop (due to usage of drugs) when shot by the then adopted 38 caliber pistols the military used. They realized they needed “stopping power” (oh no! – that’s where that term came from!).

Colt developed the venerable 1911 pistol in response based on the 45 ACP and it was adopted by the military. Thus, the “45” and 1911 go hand-in-hand.

What else needs to be said?

Well, the pistol and caliber stayed in use in the military until the M9 was adopted in the 1980’s. The main reasons it fell to the “lowly” 9mm caliber and the Beretta 92F style frame was two-fold: a) The need to have higher capacity guns. The 1911 (unless double stacked) only held 7-9 rounds. Double stacked frames were very large for the average person’s hands. b) The desire by the U.S. government to standardize with NATO standards to allow U.S. troops to be more ubiquitous with other nation’s soldiers.

The 45 ACP can be loaded from 64 grains to 255 grains, with most loads being in the 185 – 230 grain range traveling at speeds between 850-1100 fps. An average 185 grain 45 ACP round can penetrate 15″ with an average expansion size in the .83″ range. The 230 grain 45 ACP round can penetrate 14″ with an average expansion size in the .9″ range. That is nearly an inch of mass twice that of the mass of the 9mm Grasshopper.


This is Idiocracy – The Movie (freebie)

Remember the movie Idiocracy? Well, welcome to the gun communities version of Idiocracy. Every time we ask or cater to this question, we are spraying Gatorade on our crops, Costco is the only store left, Locke isn’t dead and Cheeseburger Eddie is the president!

Let’s stop!

Game Over, Right?

Why stop? I mean the previous section JUST pointed out that a 230 grain 45 ACP bullet delivered 2x the mass at nearly 1.5x the expanded size on a terminal target – game over, right?

Wrong… There is a lot more than that going into what caliber is better. Let me give you an example.

When I was in Special Forces, because I was the “big guy” on my team, I often carried the M60, a 308 (7.62 NATO) machine gun. Later, this gun was replaced by the SAW (Squad Automatic Weapon). The M60 is that machine gun you see hanging in helicopters when the door gunner is firing – yes, that big ole thing! To say the least, it was a very formidable weapon and far more than the puny M16 the rest of the guys carried (5.56 vs 7.62…for a future episode of Caliber Wars!).

Though, it did come with a LOT of drawbacks. It was heavy. The ammunition was even heavier. The ammunition was not stored in nice neat things like magazines, but it was on a belt. The gun had massive recoil compared to the M16. If you had to shoot it, you had to shoot in bursts and be careful not to overheat the barrel. Literally, the barrel could glow and melt. Finally, it came with a LOT of maintenance.

At the end of a long day of humping a rucksack and carrying the M60, I was beaten. Rambo I was not (apparently).

An Aside – Let’s All Get Along

Before we get into our final, Tombstone-like, gunfight at the O.K. Corral, let’s set some things straight.

Ok Corral

Photo courtesy of

  • Any caliber can kill.
  • Stopping power is a myth (see our “Myth of Stopping Power” article).
  • While physics is true, life is full of chaos.
  • Shot placement will and always does mean more than caliber.
  • If a person cannot effectively shoot a gun, then what does the caliber matter?
  • Sometimes, 3 smaller/less powerful shots are better than one larger/more powerful shot.
  • It takes longer to engage 10 targets with a gun that has 7 bullets than one with 15 bullets.

Can’t we all just get along?

9mm vs. 45 ACP Shoot Off

O.K., finally you are all thinking this guy is just the blowhard! I have taken you on this long ride to FINALLY have the shoot off! And here it is…

9mm Pros:
  • not as intimidating
  • less recoil
  • typically more rounds
  • generally overall lighter weight (unloaded and loaded)
  • smaller carry profile (generally)
  • can find ammunition anywhere in the world
9mm Cons:
  • recoil has more impulse
  • significantly less terminal ballistics, but bullet compositions have neutralized some of the difference
  • have to load for sub-sonic
45 ACP Pros:
  • intimidating
  • significant terminal ballistics
  • recoil is less impulse
  • can find ammunition anywhere in the world
  • sub-sonic out of the box
45 ACP Cons:
  • recoil is heavier

    And The Winner Is… – Poor Steve Harvey!

  • heavier gun loaded and unloaded
  • larger profile (generally)

And the winner is…

Envelope please…

Miss Universe 2015 is Miss Columbia, uh wait, hang on…I made a mistake…it is Miss Philippines.

Well, in this case Mr. Harvey, you are right… Both win. It all depends on the shooter.

Final Thoughts

I will be honest with you. I carry both. My “go to war” gun is normally a 45 ACP. My executive defense gun is a 9mm. I like both. Here are a few parting thoughts that may help you in your decision…

  • General Conceal Carry – 9mm… it is lighter, lots of options, and large capacity (note I conceal carry a 45)
  • Backup Gun – 9mm… smallest footprint backups are controllable, lots of options, and large capacity
  • Tactical/Go 2 War – 45 ACP… ballistics for any occasion, subsonic, best terminal ballistics options
  • Zombie Apocalypse – Both… Zombies only die from head shots, (WWZ style) then probably a 9 for the round count!
  • Bug Out (Executive) – 9mm… keeps weight in minimal bug out bag down, more ammo.
  • Bug Out (Full) – 45 ACP… A gun for any occasion that follows a full bug out.

By the way, the first reader who can tell me how many movie and TV show references I have hidden in this article (and specifically the references) they will get a prize. Let’s see how many of you can guess it correctly. I bet there is one that you won’t get!

From Quora:

Read our article on The Myth of Stopping Power

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