Free shipping on BCA uppers and riflesFree shipping on BCA uppers and rifles

9mm vs 45 ACP: Full Comparison

9mm vs 45 ACP: Full Comparison
August 1, 2023 Edited August 17, 2023 374 view(s)
9mm vs 45 ACP: Full Comparison

Today we find ourselves at the crossroads of the two most popular centerfire autoloading calibers of all time, perhaps even the two most popular centerfire handgun calibers: the 9mm Parabellum and the .45 Automatic Colt Pistol (ACP). These two calibers are old hands in the business yet remain at the top of the heap after well over a century of use, although for very different reasons. 


The 9mm is light, efficient, and easy to cram a ton of cartridges into even a small pistol. The .45 is heavy and slow, a real heavyweight big-bore. Which one is best? Let’s find out. 


A History Lesson

Our first stop is at History 101 for these two calibers. As I said, they are both old, introduced at the beginning of the 20th Century. But like a fine Scotch, they have only improved with age. 


9x19mm Parabellum

The 9x19mm goes by a few names:

●     9x19mm Parabellum

●     9mm Parabellum

●     9mm Luger

●     Or simply 9mm


None of these is incorrect nomenclature, although the most correct historically may be 9mm Luger. The 9mm was designed in 1901 by Georg Luger in beautiful Austria. Since then, it has become the undisputed King of handguns and sub-machineguns. It started out life in the infamous Luger pistols and then sub-machineguns used by the Third Reich but has since found life in the holsters of countless LEO and military members, private citizens, and of course, the world-class Uzi and MP-5 subs. And these are just a few examples. 

Georg Luger portrait.

Figure a


NATO's Adoption of the 9mm

Perhaps the biggest feather in the cap of the 9mm was its adoption as the standard handgun caliber by NATO, and the U.S. military. In 1985, the U.S. DoD upended some seven decades of tradition, ending their use of the M1911 in .45 ACP and adopted the Berretta M9, which was the standard issue sidearm until the M17/M18 was announced in early 2017. 

Being the NATO standard pistol cartridge does not mean that the M9 was the standard pistol; most countries went with the Glock 17 or 19.


.45 Automatic Colt Pistol (ACP)

.45 ACP displayed on a table
Designing the .45 ACP is perhaps John Moses Browning’s great achievement (besides all the other incredible stuff he designed). He designed the .45 ACP in 1904, just three scant years after Georg Luger designed his 9mm. Could these two heavyweights ever have guessed that their brainchildren would still be the most popular pistol calibers well over a century later? It’s hard to say. 

John Browning portrait

Figure b


The .45 ACP was purpose-built for the U.S. military, who were ready to turn in their .38 Long Colt caliber revolvers due to a lack of stopping power during the Philippine-American War. This would play out again in World War II when the same thing happened against the Japanese. Even though the M1911 was standard issue, a number of .38 caliber revolvers remained in service with various branches. It was again confirmed ineffective in anti-personnel applications, particularly using standard ball ammo. 


The M1911 entered service in 1911, and the improved M1911A1 entered service in 1926 and would stay in service until 1985, when the Berretta M9 replaced it.

M1911 Handgun

Figure c


Popular Pistols For Each

The most popular pistol caliber globally is the 9mm, and the .45 ACP is the second most popular. Not surprisingly, the possibilities are basically endless for pistols chambered in each. 



The most popular autoloading pistols in the world are the Glock series of pistols, namely the Glock 17 and 19. But they are far from the only options; there are hundreds, or probably thousands, of pistol brands and models in 9x19mm

Glock 17 held to show side view.

The big advantage to Glock is the slew of aftermarket parts available, dirt-cheap magazines, plus the availability of pistol caliber carbines using Glock mags makes it a perfect complimentary platform. Also, the great thing about Glocks is that the mags are interchangeable between models in terms of smaller frames using larger mags; a G26 can use G19 or G17 mages, etc. 


The 1911 is still wildly popular in the .45 ACP space, but tons of great options are available, from Glock, Smith & Wesson, and Tanfoglio, to name just a few. Also, we offer pistol caliber carbines in .45 ACP that are the perfect patrol complement to your Glock sidearm in .45 ACP. 

Tanfoglio .45 ACP handgun on display


Choosing Which One Is Right For You

You are the only one who will know the right sidearm caliber for you. The 9mm is one of the most powerful calibers ounce-for-ounce; while having a much smaller case than the .38 Special, the 9x19mm handly outperforms it every time. Also, you can have a pistol the size of a J-Frame that carries double the capacity. If you are in a state that doesn’t limit magazine capacity, the 9mm is the natural pick for a CCW. It packs far more punch than the .380 ACP in a pistol that is only marginally larger. Also, the recoil is manageable in the 9mm, only slightly sharper than a similarly sized .380, and certainly more controllable than any .380 mouse guns (sorry guys, the LCP is great but impossible to handle). 


.45 ACP In Capacity-restricted States

There are some states out there that believe that your right to defend yourself ends after the tenth round. Weird, we know. If you live in one of these states, the .45 ACP is a great option. Big and heavy, you might as well get the burliest round in your hands if you can only stack ten rounds in the grip, trading out capacity for superior energy transfer.

Carrying a .45 ACP is also not bad in predatory or aggressive animal (feral hogs) areas. 


Pistol Caliber Carbines

PCCs are a great complement to your carry pistol, especially when you find one that pairs up in caliber and magazine. Our 9mm and .45 ACP (and 10mm) PCCs use Glock magazines, so you can pair them up with your Glocks and feel totally confident during your walks in the woods or throwing it in the pickup as your truck gun.

Pistol Caliber Carbine held to see side view.

Parting Thoughts

We didn’t dive too deep into the ballistics or the performance of these two classic GOATs because that information is everywhere. Instead, we looked at the history, where these two dissimilar calibers came from, and where they really shine today. Both are well over a century old and show no sign of slowing down. 


If you’re looking for a 9mm or .45 ACP pistol, we’ve got ‘em. We can also help you with your sick Glock or Sig 320 build. 




Please login to comment.

Don't have an account?

Sign Up for free
Copyright © 2024 Bear Creek Arsenal, LLC. All Rights Reserved.