.45 ACP vs 9mm: Which Is Better?

Yes, the 9mm Luger shoots a smaller caliber and lighter bullet than the .45 Auto. However, it shoots it much faster, with much less recoil, and 9mm handguns have a higher capacity. Between these two, shot placement and bullet performance will matter more.
Yes, the 9mm Luger shoots a smaller caliber and lighter bullet than the .45 Auto. However, it shoots it much faster, with much less recoil, and 9mm handguns have a higher capacity. Between these two, shot placement and bullet performance will matter more.

The more than century-old debate of .45ACP vs 9mm rages on. But in the end does one cartridge really outperform the other?

How does the .45 ACP stack up against the 9mm:

  • Unfired there’s only 0.095-inch difference between .45 and 9mm’s bullets
  • Both cartridges can be designed to deliver more tha a foot of penetration in a human body
  • While the .45 does fire heavier bullets, a 9mm gun generally has more capacity

Are you as sick of hearing this argument as I am? This has been an ongoing debate for more than 100 years. Here’s the thing: There’s no definitive way to prove which cartridge is better. Yeah, I know, you’re thinking that the .45 ACP shoots a larger-diameter and heavier bullet, therefore it has to be better. Ok, let’s consider the facts, and disregard the hype, so we can better understand this squabble.

First of all, an unfired bullet .45 ACP bullet is exactly 0.095 of an inch larger in diameter than an unfired 9mm Luger bullet. That’s just a shade larger than the thickness of a quarter. After the bullet deforms due to impact, the difference in diameter is really what matters, and that varies a lot.

Much like the shadows they cast, from a terminal performance standpoint, there is really not much difference in the 9mm, 40 S&W or .45 Auto.
Much like the shadows they cast, from a terminal performance standpoint, there is really not much difference in the 9mm, 40 S&W or .45 Auto.

Secondly, because the 9mm Luger operates at a higher pressure — 35,000 psi as opposed to 21,000 psi for the .45 ACP — it launches its bullets much faster. This, in conjunction with the faster twist rate of 9mm barrels, makes it easier to design bullets for the 9mm that will reliably expand over a broader velocity spectrum. A bullet fired from a 9mm Luger has twice the rotational velocity of one fired from a .45 ACP.

Thirdly, ammunition for both cartridges can be designed to deliver more than a foot of penetration in a human body. The FBI says that’s about all you need. Since both end up at about the same diameter, and both penetrate about the same distance, what else really matters?

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Finally, the 9mm can be housed in smaller and lighter handguns. In similar-sized handguns, it can also hold more ammunition. And, because the 9mm Luger delivers less recoil, you can put more shots on target faster. The .45 ACP is not really any better than the 9mm Luger, it’s just different. Pick the one you like, learn how to shoot it and stop wasting time arguing about something neither you nor anyone else will ever be able to prove.

Editor’s Note: This article originally appeared in the March 2019 issue of Gun Digest the Magazine.

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  1. Its shot placement and proper timing, not how big one’s asset is. It all boils down to mastery of weapon with the caliber of choice. A .22 is as effective as any if properly aimed at a vital part: eyes, knees, hands, genitals, no human nor animal is invulnerable to a speeding bullet. In the “elements of combat power” doctrine, a well-trained shooter should be able to fire and hit effectively with speed and accuracy under pressure, while keeping protected from the line of opposing resistance. Never blame the gun nor the bullet for one’s ineptitude and lack of ability to stop and put down the target under any circumstance, on the range, hunting ground or in the battlefield. History shows the victor in any confrontation is always attributed to proper tactic and good maneuvering arising from constant training and discipline and not how big a stick one had.

  2. If we read the Thompson/LaGarde tests, the real shortened report by LaGarde, not something that some current gunwriter put out, we find that the 45 works better. The anemic 455 Webley out performs the 9mm with hardball or a FP fmj (the loading at the time that the gunwriters were all agog about when it came back out 20 odd years ago). If the small calibers do not expand they are not nearly as reliable as hard ball from the 45 ACP. Read the account of Alvin York stopping a squad of charging Germans with a 1911, they charged at close range when his 1903 was empty. He not only shot them all down he shot the LAST ONE FIRST. I have 3 calibers in semi-auto, 9mm, 38 Super and 45 ACP. I carry the LW Commander in Super most with 1350 to 1400 fps 125 gr HP handloads, 357 mag/357 Sig ballistics. If I need better concealment I carry a the little 9 since its better than nothing and its only for a short time once a week. The current 45 is all steel and pretty heavy. But it will work pretty well even with hardball. The 9mm will not. The Super with the 1300 fps (1930s loading) 130 gr blunt RN its supposed to be loaded with for FMJ is better than 9mm hardball on all counts. Someone mentioned helmet penetration. I had a 45 in VN for kicks I shot a GI pot at about 20 ft with it. Had someones head been in it the dent was deep enough to kill. Helmet penetration is a fools guide to defensive handgun performance. The thing about a pistol is, as in York’s case, its the last resort, emergency weapon for the soldier. If you are close and need to use a handgun it better keep the bad guy from shooting you. The 9mm has too spotty a reputation for me to trust as my normal carry caliber. Its also poor on window glass. Such as having to shoot through a windshield. Finally in conclusion LaGarde stated that the only thing that would reliably stop a man was a 3″ solid shot. But in general bigger is better.

  3. My EDC is 9mm. I have 2 of them. I’d carry a .45 if it would fit in my pocket. I also have 2 of them. An alternate that is small enough to fit in my pocket an probably should carry more often is a .357 magnum.

  4. How come I hear of cops emptying their 9mm weapons at a suspect and they still keep coming at ’em?? I don’t think that will happen with a .45.

    There is only one way to address this issue. Half of cops in America carry the 9mm and the other half carry .45 after 3 years tally all the results.

    That will settle it once and for all.

  5. Pistolero Magazine in the 1980’s shot barn yard hogs with the 9mm and .45 acp and found no difference in killing power at all. In 1945 the U.S. Government tested the 9mm and .45 acp on a steel military helmet. The .45 acp bounced off the helmet at 35 yards while the 9mm penetrated the helmet at an astonishing 125 yards proving that the 9mm with its higher velocity, flatter trajectory and higher capacity (they used a Canadian High Power) that the 9mm was the superior combat pistol and caliber period.

  6. Circumstances and bullet placement dictate the outcome of targeting humans. Trying to make a science out of chaos is pointless. Most gunfights do not resemble what takes place in movies. The average individual armed with a pistol will be lucky to unsheathe their weapon in a timely manner and place their first shot where it will stop a miscreant. Most people who carry for protection don’t practice enough. And if they do, a timely swat on the head will out them. Practice, physical fitness and awareness is more important than quibbling over ballistic niceties.

  7. Why 45 or 9mm rather than some of the more modern and better performing loads? For me it is just a matter of cost. The old cartridges are a fraction of the price of others, and much more easily found.

  8. The question I keep asking, to which i have yet to get an answer, is why are we still arguing the merits of two cartridges that are both over a century old, instead of moving on to newer, more effective choices? For example, the .357 SIG and the .400 CorBon both outperform these two icons, but both are spinning down the drain of consumer rejection, while these two old warhorses just keep going. Why is that?

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