Semi-Automatic Pistols: Who is the Caliber King?

Semi-Automatic Pistol Cartridges

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The Big 3 Semi-Automatic Pistol Cartridges

It’s not a stretch to say that the 9mm Parabellum, .40 Smith & Wesson, and the .45 ACP are the 3 most popular semi-automatic pistol cartridges around. At least in the United States, but I am guessing their reach, at least for 9mm, is worldwide.

The caliber war among these 3 highly respected rounds has been around since the beginning of … well, a long time ago. Which is the best of the top 3 semi-auto calibers? 9mm vs. .40 S&W vs. .45 ACP. The definitive answer: none. Well, at least that’s my feelings, others might vary. Honestly, there are a few reasons I come to that conclusion, some are pretty obvious, others less than you might think. The reality is, there just isn’t that much difference between the cartridges, and what it comes down to is personal preference. Yes, I know I will get a lot of flak for saying that, but oh well, its truth, and its science. If you don’t believe me, just look it up. The test results, by dozens of industry leaders, don’t lie.

The other truth is, there are a few semi-automatic pistol cartridges that have far superior ballistics than any of these three, if you were talking purely in energy, velocity, and bullet size, economics aside of course. In fact, the most powerful, most versatile semi-auto rounds out there are probably some of the least popular. I’ll let you speculate on that… anyway, I digress…

Cartridge Comparison: The Smallest vs The Largest

Let’s start with the obvious reasons. First off, OAL and case diameter for these semi-automatic pistol rounds range from .355″ for the 9mm to .452 inches for the .45 ACP, with .40 S&W falling dead center between the two. It seems though, that there is very little payoff for the variance in size. Consider the loading of 9mm vs a .45 ACP. Lyman’s 49Th addition lists a load for 9mm as a 147gr TMJ, using Alliant Power Pistol, a max load of 5.0gr of powder, moving at 1043fps with 32,400 C.U.P. Flip over to .45 ACP, we’ll look at the 230gr TMJ. The load data for this lists a max load of 7.2 gr of Alliant Power Pistol, but is only moving 858fps with 16,600 C.U.P. So, the .45 ACP has a much heavier projectile (+83 grains) but uses 2.2gr more powder to push that heavier projectile, but is also pushing it 185fps slower (more powder + slower speed + pricey projectile = bad economics) with about half the pressure.

So essentially, one is small, fast, and light. The other is large, slow, and heavy. The trade off? One reaches out further with more energy, but is smaller and therefore will dump its energy quicker. The other starts off slower, but is heavier and retains energy at close ranges. On the side of .45 ACP you better believe at a closer range that thing is gonna put a much bigger hole in you, and is going to dump all that mass and energy on impact right into your meatiest parts. Semi-Automatic Pistols were born to shoot the .45 ACP, and it’s a proven man stopper. Essentially, they both have their purpose and proper application.

Cartridge Comparison: Right in the Middle

Where does the .40 S&W fit into this? Well, you probably guessed it…right in the middle. Medium sized chunk of lead, but moving at speeds exceeding the .45 ACP. It borrows speed from the 9mm, and size from the .45 ACP. So the .40 S&W should win right? I mean, logically, it borrows the best elements from both worlds and combines them. Well, not quite. There are other factors to consider here, not the least are reliability and muzzle control of the shooter. The .40 S&W, while being a fine cartridge certainly comes in 3rd place for popularity amongst these 3 semi-automatic pistol cartridges, and for a few good reasons.

  1. It’s not that economic. You have a smaller projectile, but you are paying the cost of .45 ACP. You can make up for this of course through reloading, where the cost is almost identical at times to the 9mm.
  2. You get less rounds. Albeit, not by much. Yes, it is fast and certainly heavier than a 9mm, but again, don’t forget that Springfield XDm with 19+1 rounds in 9mm.
  3. Control: Many people just find it to be harder to maintain accuracy and follow up shots. This in turn, requires more practice, more ammo, and more time. This is not a bad thing, if you can afford the time and money, but I can see where it discourages some folks from choosing this round. Personally, I would not hesitate to pick up a .40 and spend some time with it. It’s still a pretty great pistol cartridge, and if you need proof of its quality and reliability, look at how many Law Enforcement Agencies use it around the world.
  4. Going back to the Lyman 49Th Edition, a 180gr JHP (They don’t list a TMJ or FMJ in standard weights) is listed as a max load of 6.7gr of Alliant Power Pistol, moving at 974fps with 23,100 C.U.P. So really, it does fall right in the middle. Not a lot faster than the .45 ACP and still slower than the 9mm, but with far less pressure.

Among semi-automatic pistol cartridges, the .40 S&W could really take the lead in terms of economics. I guarantee, if you saw commercial prices hovering closer to a little above 9mm, people would pick this round 8/10 times off the shelf purely for the combination of decent ballistics and a good price. Unfortunately, this round still seems to be hovering at near .45 ACP prices, which is unfortunate to say the least.

Whose the real Pistol Cartridge King?

If you were to dig deep into the ballistics and testing of these 3 Semi-Automatic Pistol Cartridges, in various loads and manufactures, you would see the difference between them is a little give and take, but not a ton of difference overall. They all essentially have their own respective applications, and definitely all perform where they are needed. But every time you here some person spouting off about how their cartridge of choice is far superior to yours, remember, the data doesn’t lie. They all have their strengths and their weaknesses. Practice and shoot what you feel comfortable with, and stay confident with that round. Quick and accurate shot placement, no matter the caliber, will beat ballistics any day, that much is fact.


  1. I’ve shot all 3 over the years, and, although the .40 and .45 can be fun, I’ll stick with the 9mm for defense. I have some physical limitations, so need the lightest, yet most potent, with as little recoil as possible.

    • I’d say that’s a smart decision. Use what you are most proficient in, practice with it, and be confident in your abilities.

  2. I’m pretty new to shooting and having only tried a 9mm, I found the recoil perfectly manageable. I can work with it, straight away. I obviously can’t comment for .40 S&W or .45 ACP yet, but I do imagine the recoil more suited to someone with more experience. Would love to try them out and prove the article to myself, though!

    • 9mm is a great place to start. Honestly, of the guns I own and the ones I have shot in past years, I still go back to 9mm just because it is so much fun to shoot. I hope you enjoyed your experience, be safe and practice. Its really a great sport and culture with a lot of great people!.

  3. I like 9mm the most. It has a very easily manageable recoil and I shoot targets mostly. It’s also the cheapest so when you’re operating on a tight budget, every dollar counts.

  4. The article is a longer version of almost exactly how I explain it. When speaking in terms of self defense and concealed carry, you’re basically looking at three factors – weight, number in a mag, cost to practice at the range. For me, 9mm is the hands down winner. It’s lighter, cheaper, and most of my 9mm version pistols fit a few more rounds in a thinner mag. Some people may want the 45 for what they call “knock down power” and that’s fine, but 9mm hollowpoints should provide something similar. Some may want the 40 for “best of both worlds” or a “happy medium”, but I don’t think the criminal will know or care if the weapon you use to defend yourself with is 9mm, 40, or 45. You might as well save the money, go with 9mm, and practice a little more.

  5. I’m trying to find some good ammo, but it’s become ah problem for me I can’t seem to figure out the right place to shop.

  6. The 9mm pistols are always going to have the faster travel and less recoil. They are the most common and you can practically find a lot of 9mm handguns in the store. The .45ACP round is the heaviest of those three in the article. There are some big handguns that use the .45ACP like the Glock21 but I would prefer the 9mm since its most common.

  7. Here’s some interesting information on the semi – automatic pistol (25acp)
    It was designed by John Browning in 1906 as a straight walled pistol cartridge. Now the 25 auto is more of a novely purchase and most people will buy a 380 instead of a 25

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