9mm vs. .45 ACP: Let’s Talk About It

QUICKEST WAY TO START A (NON-POLITICAL) ARGUMENT DOWN AT YOUR LOCAL GUN STORE? ASK THEM 9MM VS. .45 ACP! HERE IS A CALMER TAKE ON IT.

A tale as old as time the early 1900s, 9mm vs. .45 ACP is a fight starter on every firearms forum found on the internet. Some of this is for good reason, most of it is angry people yelling at clouds.

I have my opinion, and I’m sure you will have yours. Before we get into that, let’s take a look at the hard facts and differences between these two legendary cartridges.

QUICK AND DIRTY

A very quick look at these two calibers is basically 9mm is lean and fast, and .45 ACP is thick and heavy. However, that description might lead you to the wrong ideas.

Both cartridges are great pistol rounds and are incredibly reliable. 

Both are combat-proven, both are insanely popular in the United States, and both are available in a wide range of weights and styles, with a huge range of pistols and pistol-caliber carbines chambered for them.

If you want my recommendation, 9mm is a superior cartridge for almost every application.

I can already hear some of you angrily typing in the comments to tell me why I’m wrong, but I stand by my choice.

CARTRIDGE SPECS

	.45 ACP	9x19mm
Bullet diameter	.452 in (11.5 mm)	.355 in (9.01 mm )
Neck diameter	.473 in (12.0 mm)	.380 in (9.65 mm)
Base diameter	.476 in (12.1 mm)	.391 in (9.93 mm)
Rim diameter	.480 in (12.2 mm)	.392 in (9.96 mm)
Case length	.898 in (22.8 mm)	.754 in (19.15 mm)
Overall length	1.275 in (32.4 mm)	1.169 in (29.69 mm)
Velocity	700 - 1150 FPS	950-1400 FPS
Maximum pressure	21,000 psi (140 MPa)	34,084 psi (235.00 MPa)

Size for size, these are fairly close to each other — just .45 ACP is a little taller and a lot thicker. 

This mostly comes into play when it’s time to look at magazines. While you might fit 7 rounds of .45 ACP in a single-stack magazine, you’ll get 9 or 10 in a single-stack 9mm.

For double-stack pistol magazines, 10-15 is normal for .45 ACP whereas 17-22 is more common for 9mm.

PRACTICAL APPLICATIONS

HOME DEFENSE

Both calibers are commonly chosen for home defense and both will get the job done.

.45 ACP being heavier and slower tends to penetrate more, especially misses that only go through drywall.

Even a bullet designed for defense that expands on impact has trouble shedding its momentum if it only hits drywall.

9mm being lighter loses energy more quickly when passing through layers of drywall. 

Personally, I wouldn’t choose either as my top home-defense choice, since both .45 ACP and 9mm over-penetrate more than 5.56 NATO or #4 buckshot.

But given the choice between the two, 9mm has a major advantage since you can fit more rounds in a magazine and recoil is easier to control.

HUNTING

While handgun hunting is normally done with larger calibers like .44 Magnum or something truly large like .454 Casull, .45 ACP can get the job done on mid-sized game like whitetail deer at close range.

Because .45 ACP has decent penetration and carries a fair amount of energy, a well-placed shot can drop a deer.

However, even under ideal conditions hunting with .45 ACP is not something a beginner should attempt. Shot placement is critical as is the distance to target. 

The marksmanship and hunting skill required for handgun hunting is something that really should be left to experienced shooters.

9mm is simply not suitable for harvesting game when there are so many other, better, options.

CONCEALED CARRY

One of the most common applications for both of these calibers is for CCW. 

Both 9mm and .45 ACP come in pistols that are fairly easy to conceal, depending on what you choose.

Take two of the smallest popular CCW pistols in each caliber, the Glock 26 in 9mm and Glock 30 in .45 ACP.

Really, they are basically the same size — the Glock 26 is 6.5 inches in overall length, 1.26 inches in width and 4.17 inches tall, whereas the Glock 30 is 6.97 inches in length, 1.38 inches in width and 4.8 inches tall.

While the Glock 30 in .45 ACP is slightly larger, it really is slightly.

At this size, they even have the same capacity, 10 rounds in a flush-fitting magazine.

The larger the gun is, the more of a difference the size of ammo matters. 

Looking at the full-size versions of these guns, the Glock 17 and Glock 21 — the dimensions remain basically the same compared to each other, but the capacity difference is huge.

Glock 17 holds 17 rounds of 9mm, the Glock 21 only holds 13 rounds of .45 ACP.

The other large difference is weight. A loaded Glock 17 is about 32 ounces, a loaded Glock 21 is almost 39 ounces.

.45 ACP carries more energy but has reduced capacity and harder recoil. This makes it harder to shoot and harder to control. While this can be trained for, it requires a lot more range time to become proficient.

9mm is lighter, has more ammo per mag, and is much easier to control.

RECREATIONAL SHOOTING

It entirely depends on what you like, but both calibers are awesome for blasting at the range with.

9mm is going to cost you a bit less to shoot and that can make a big difference in how much you shoot. But .45 ACP has a longer/smoother recoil pulse making it easier on your hands to shoot for long periods of time.

I can’t pick a favorite between these two for just plinking with, I love both.

COMPETITION SHOOTING

While both calibers have a place in comp shooting, you’re far more likely to run into 9mm than you are .45 ACP.

There are some divisions in some shooting sports made to allow .45 ACP shooters a semi-level playing field, but 9mm is going to be far more common.

From the cost of ammo and guns to the style of shooting that most competitions are designed for, 9mm simply performs better on almost every level.

If you’re a die-hard .45 ACP fan, you can still shoot it at most competitions — but expect to get your times smoked by the 9mm dudes.

LETHALITY

Much of the debate between 9mm and .45 ACP comes down to what caliber is more deadly.

Everything from foot-pounds of energy to muzzle velocity to “stopping power” is quoted and thrown around trying to make a case for one or the other cartridge.

Let’s do some bare-bones comparison before we get into the more opinionated part.

I’m looking at Hornady defensive ammo because their ammo is great quality, fairly easy to find in stock at most major retailers, and they publish a ton of info online making it easier to research.

Hornady defensive ammo comes in a range of styles and flavors for both 9mm and .45 ACP. From the 100gr FTX 9mm to the 220gr .45 ACP +P you can find just about anything.

But for this comparison, let’s stick to Hornady Black and Hornady Critical Duty +P since they come in 9mm, .45 ACP, and +P.

	Muzzel Velocity	Energy
9mm Luger 115 gr XTP Hornady BLACK	1,155 FPS	341 ft⋅lbf
9mm Luger 124 gr XTP Hornady BLACK	1,110 FPS	339 ft⋅lbf
45 Auto 185 gr XTP Hornady BLACK	970 FPS	386 ft⋅lbf
9mm +P Luger 124 gr FlexLock Critical Duty	1,175 FPS	380 ft⋅lbf
45 Auto +P 220 gr FlexLock Critical Duty	975 FPS	464 ft⋅lbf

That’s a lot of numbers but stick with me — basically what you’re seeing is it really just depends on what you choose. If you look at the weakest (on our chart) 9mm Vs. the most powerful .45 ACP (again, on our chart) it might look like .45 ACP smokes 9mm in energy.

But look at the 124gr +P 9mm Vs. the 185gr .45 ACP and there is only a 6 ft-lbf difference. That is a meaningless amount of energy.

Now personally, I normally use SIG Sauer V-Crown as my defensive ammo of choice.

124gr 9mm SIG V-Crown runs at 1,165 FPS with 374 ft⋅lbf 230gr .45 ACP SIG V-Crown only runs at 830 FPS and 352 ft⋅lbf actually making it weaker than 9mm.

Let’s take a moment to let the .45 ACP diehards collect their blown minds.

This is the numbers and math part, but there is a lot more to lethality than just numbers.

SHOT PLACEMENT

When it comes down to it, a .22 LR to the heart is more effective than .45 ACP to the finger for stopping a threat. Shot placement is king. Always. The debate stops here.

While a .45 ACP with the right ammo might do more damage when it hits something critical, 9mm gives you a better platform to make hits with and normally more ammo in each magazine to do it with.

Because of the major advantages 9mm has in capacity and follow-up, it is generally a better choice for self-defense. 

If you take the time and spend the money to train with .45 ACP effectively you can overcome most of the clear-cut advantages that 9mm has.

But what have you actually gained? Personally, I don’t think you’ve gained much if anything.

If 9mm is good enough for the Army, Marines, Navy, Airforce, Coast Guard, and FBI — I’m willing to say it’s good enough for me in a dark alley.

COST & AVAILABILITY

Both calibers are massively available basically everywhere in the USA. Any gun store that doesn’t carry both (outside of times of panic buying) shouldn’t even call itself a gun store.

Cost is clear cut, 9mm is cheaper almost always and almost no matter what. Even in bad times, 9mm is generally cheaper.

At the time of writing the cheapest new brass cased 9mm I can find is 24 cents per round, $240 for 1,000.

At the time of writing the cheapest new brass cased .45 ACP I can find is 44 cents per round, $440 for 1,000.

Personally, during the ammo shortage of 2021, the highest I saw 9mm at my LGS was about 50 cents per round, but .45 ACP was pushing 90 cents a round.

Prices will always favor 9mm. It’s cheaper to make, you can ship more of it per pound making logistics cheaper, and there is more demand for it so the economy of scale helps reduce the price.

Defensive ammo is going to be closer between the two, but 9mm is still generally going to be cheaper.

My SIG V-Crown is 60 cents for 124gr 9mm and 72 cents for 230gr .45 ACP. That’s actually not too bad.

LOOSE ROUNDS

I love .45 ACP, it’s one of my favorite calibers to just get out and shoot with. After two world wars, there is something deeply American about .45 ACP.

But for competition and self-defense, I strongly recommend 9mm and choose 9mm myself.

Both calibers have a place in your safe and both calibers will serve you very well.

Hopefully, this comparison has helped answer some questions and given you something to think about.

Here are some more articles for you!

• The 9mm Carbine: Part SMG, Part Pistol, Pure Utility
• Best 9mm Pistol For Defense
• RECOIL TV: 45 ACP Versus 9mm UNDERWATER
• ATI FXH-45 Moxie: Not Your Grandpa’s 1911