.45 ACP vs. 9mm: The Ultimate Comparison


And so it continues, indeed. Here we go again…

One of the most popular non-contact (well, most of the time) sports that gun owners indulge in is arguing which of these two pistol cartridges is better for self-defense. I was asked to add my two bits to the discussion, which I am glad to do. I have my opinions, of course, as does anyone who has ever shot one or the other of these two venerable pistol rounds.

[This topic is so controversial and intricate that we at Bear Creek Arsenal decided to use 2 writers to give you different perspectives. Enjoy!]


.45 ACP

The .45 has been around since 1905 when John Browing’s first semi-auto .45 caliber pistol saw the light of day. Later, the cartridge was developed further – it went from a 200-grain FMJ to a 230-grainer at 850 f.p.s. – and was paired with the Army’s newly-adopted Model of 1911, adopted in that year. It was a first for the U. S. Army – they adopted a self-shucker and not a revolver. Here’s an interesting side note: when it was introduced, it took a small pistol primer. Nowadays most of the loads will use the large pistol variety, although I have a coffee can full of SPP cases that a few manufacturers use.

There’s a backstory, of course. Without re-hashing the ancestry of the old .45, you can read it here, elsewhere on this blog. I wrote a concise description of the .45 ACP and included a fairly detailed history for my article on the old warhorse. It makes for an interesting read, especially if you’re into cartridge development and historical aspects thereof. It served us (“U.S”.) well until 1985 when it was replaced by (of all things) the 9mm. Hmm… More on that later. (Read my history of the .45 to catch my inside joke… sorry!).

The ol’ .45 is still hanging in there… the cartridge and its original launcher, the 1911 pistol, are going strong with a few special force units in our military. Also, civilian shooters haven’t abandoned it to any great extent. Heck, my Ruger Blackhawk in .45 Colt even came with a .45 ACP cylinder. The old guy is still around and kicking!

45 acp ammo on workbench


AKA 9mm Luger and the 9×19, the 9mm is one cartridge that has truly benefitted from NATO adoption. It pre-dates the .45 ACP by three years… Georg Luger finalized his design and brought it out in 1902, pairing it with the Luger pistol. Firing a 115-grain bullet at 1200 f.p.s. (or a 124 around 1100), the 9mm was always “zippier” than the .45 ACP. (We’ll look at ballistics next). Why is the 9mm so popular, even more so than the .45? There are a couple of reasons. I mentioned one already – NATO adoption. This happened three years after I made my appearance – it was adopted by NATO in 1955. There was a definite European influence in the decision-making, but that’s OK. The round works for its intended purpose.

Before we get into ballistics, let’s compare the two in a few criteria…

.45 ACP 9mm Weight, 50-round box: 38 oz. (230 grain) 23 oz. (124 grain) Box dimensions, 50 rounds, inches: 6 x 2 x 3 5 x 1.6 x 3 Cost, 1000 CCI Blazer Brass cartridges: $530 $319

We could go on but suffice it to say that a box (or case) of 9mm is going to be lighter, smaller and cost about 30% – 40% less than .45 ACP. Many shooters will consider these numbers before buying a pistol. Some will buy a .45, most will buy a 9mm. The 9mm seems to be the darling of the pistol world now, usurping the .45 that used to rule the roost. But is that a bad thing? I think not, and I am a big .45 fan. Let’s continue our look at the two…

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9mm round on table


We can look at all sorts of numbers when it comes to ballistics (meaning, for our purposes, terminal ballistics) comparing these two cartridges but why re-invent the wheel? You could do a Google search as I just did and, in under 6/10s of a second, return 230,000 hits. Without dissecting too many of these, some conclusions are:

  1. The .45 shoots a wider/heavier at slower velocities.
  2. The 9mm shoots a narrower/lighter bullet faster.
  3. The .45 tends to rely on bullet mass, not necessarily expansion, to take care of business.
  4. The 9mm tends to rely on expanding bullets to take care of business.

If you want to see a whole lot of gel test results for each of these rounds, check out Lucky Gunner. This link will take you to their 9mm ballistic gel test results page. They tested 52 different 9mm cartridges from a plethora of manufacturers. This is the best link I can show you in terms of what each round did to the gel; this is the place that has all the results in one chart. For .45 ACP results, go here. Penetration depth and expansion are measured, as are the velocities of all the loads. It’s quite revealing!

45 acp ammo vs 9mm ammo sizePhoto courtesy of Mike Hardesty

Stopping Power

From Guy J. Sagi:

Ammo originally issued to our troops in .45 ACP wore a 230-grain, FMJ bullet. Muzzle velocity was 830 fps, which means it left the gun carrying 352 ft./lbs. of energy. With that wide bullet its ability to stop and attacker with authority is a proven fact.

A look at Federal Premium’s 230-grain Total Metal Jacket .45 ACP load today demonstrates how propellant has improved, though. They leave a five-inch test barrel at 850-fps—a tidy increase of 20 fps—and have barely slowed at 25 yards (834 fps). Energy has declined from 369 to 355 ft./lbs., plenty to get the job done, especially if that bullet is one of today’s modern marvels.

The company’s 9 mm Luger load with a 124-grain FMJ leaves a four-inch barrel at 1,120 fps, generating 345 ft./lbs. of energy at the muzzle. At 25 yards the figures are down to1,070 and 315, respectively. The shorter barrel muddies the comparison slightly, but the figures between cartridges are close even without that extra inch for powder to burn.

Assuming a 25-yard zero, the .45 ACP drops 16.4 inches at 100 yards. The 9 mm load would require a holdover of only 9.3 inches. Energy at that distance, if you’re wondering, comes in at 319 and 255 ft./lbs., respectively.

Manufacturers don’t apparently like to publish wind drift figures. These are, after all, pistol cartridges. The increased speed of the 9 mm, however, means it spends less flight time subjected to the effects of unseen breezes.

The options available in today’s ammunition are seemingly limitless, especially in these cartridges. Propellant is more efficient and bullet performance borders on mind boggling. The versatility shows.

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Which Is Better For Self-Defense?

Which is better… apple pie or chocolate cake? I know what I’d choose but they’re both good – too good! It’s the same with these two calibers. They’re both good. It comes down to personal preference. But, there are some differences. Let’s look at it in a somewhat-objective manner. All of what I’m about to disclose here comes from my research and the pricing may or may not be accurate as of this writing.

.45 ACP 9mm Magazine Capacity: Up to 13 +/- Up to 20 +/- Gun Size, Overall: Medium – Large Micro – Large Gun Width: Medium – Wide (1.5”) Small – Wide (less than 1.5”) Ammo Cartridge Cost: $.40 and up $.24 and up Weight, 50 rounds: 38 oz. 23 oz. Recoil Energy/Velocity: 7.9/15 f.p.s. 4.4/11.9 f.p.s.

OK. Enough with numbers. Which should you choose? I have an idea or two on that one. If you are a rookie, you’ve just bought your first pistol, you’ve never shot much if any before… I’d consider sticking with the 9mm. The recoil energy is about half that of the .45 ACP’s. This is a biggy for beginners, trust me. I’ve seen new shooters flinch so hard anticipating recoil that the shot went over the backstop. Add in the other factors… ammo cost is less which will allow more practice, guns tend to be a bit smaller and lighter, magazines can hold more… it does tend to point to the 9mm.

Now, if you are an old-timer with a pistol, you have both avenues open to you. If you can handle recoil (let’s say you shoot .357 or .44 Magnum regularly) and the extra cost and weight doesn’t bother you, choose whichever of the two you feel most comfortable with.

45 acp and 9mm rounds lined up on table

Pros And Cons

Pros Cons .45 ACP *Big, heavy bullet *Heavier recoil – slower follow-up shots *Proven track record *Ammo weight, cost and sometimes availability *May not need expansion to work *Lower mag capacities *Guns tend to be larger and heavier 9mm *Guns tend to be smaller and lighter *Lighter, faster bullets may overpenetrate *Lighter recoil * Many different guns out there; can be confusing to first-time buyer *Ammo weight and cost *Sometimes surplus ammo is available *More types and brands of guns and defensive ammo than .45

Which Is Better?

Pistol Caliber Carbines

From Guy J. Sagi:

The flame wars will likely rage for decades in the 9 mm Vs. 45 ACP debate, but there appears to be no dissent that in the new generation of pistol-caliber carbines the nine is the clear winner. Dozens of manufacturers, like Bear Creek, offer blowback-operated semi-autos in a variety of configurations that use common self-defense pistol magazines. It’s versatile, convenient, and not hard to find a model or barrel length ideal for your shooting sports—or hunting—passion.

There are .45 ACP-chambered versions out there, but some clear advantages push 9 mm NATO across the finish line first. For one thing, it’s hard not to find a model and configuration ideal for your favorite pursuit. Then there’s the flatter trajectory and ability to use the same double-stacked magazines as your pistol, in many cases. The redundancy is an asset in a survival situation and reduces reload frequency during informal range sessions. It’s also hard to argue against the fact that it will probably be the centerfire cartridge most readily if there’s a total meltdown in society.

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From Mike Hardesty:

Let’s face it: you will choose whichever caliber you can consistently hit with. Or, at least you should. Most modern self-defense ammo in either of these calibers is going to do its job in terms of providing a comforting level of protection.

If you are looking for a carry pistol, the best thing you can do is go out and shoot several, in different calibers. If your local range rents guns, go that route. Or, if you have a friend or relative who owns a few guns, ask if you can try them out. You might want to invest in a box or two of ammo – if you go the range route, you’ll have to do that anyway.

Find the gun/caliber that you score the most hits with. Don’t worry about speed – that will come in time. Just check out how the gun feels in your hand and how the sights line up for you. Here’s an old trick… pick a spot on the wall as an aiming point. Close your eyes with the gun in a low ready position, and then bring the gun up and point the gun at that spot on the wall. Open your eyes. If the sights are close to your aim point, the gun fits your hand and points naturally for you and is worth more research. If it’s consistently very low or high, you might want to look elsewhere.

Shoot both 9mm and .45 if you can. Heck, you may like the .45 more… it’s happened. The point is to not let some other “expert” tell you what you should buy but to discover that on your own. I am blessed to have my good friend Duane’s shop as my local FFL, where I take delivery of test guns (and buy some as well). He is excellent with new owners… he pulls out what they want to see, hands them the guns, and then stands back, quietly. He answers questions but lets them do their own discovery. This is the right way to help coach a new shooter into their first carry gun. Be there for them as the expert but let them see what feels best without shoving guns at them.

Whether you are a .45 junkie or a 9mm adherent, you should shoot whatever caliber you can hit with. Remember another old saying… A hit with a .22 is better than a miss with a .45. Repeat hits on target count. Don’t let someone tell you that you MUST shoot this or that caliber. As I said above, it may not be .45 ACP or 9mm but another caliber. Figure out what you hit consistently with, procure a gun and ammo in that caliber, and then practice, practice, practice! At least that’s always worked for me. How about you? Let’s hear from you below!

[We hope you enjoyed that unique look at 45 ACP vs. 9mm. Check out our other articles such as 300 Win Mag vs. 6.5 Creedmoor and AK-47 vs. AR-15.]

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Ethan Smith is a seasoned marine veteran, professional blogger, witty and edgy writer, and an avid hunter. He spent a great deal of his childhood years around the Apache-Sitgreaves National Forest in Arizona. Watching active hunters practise their craft initiated him into the world of hunting and rubrics of outdoor life. He also honed his writing skills by sharing his outdoor experiences with fellow schoolmates through their high school’s magazine. Further along the way, the US Marine Corps got wind of his excellent combination of skills and sought to put them into good use by employing him as a combat correspondent. He now shares his income from this prestigious job with his wife and one kid. Read more >>