Do All 9mm Bullets Fit 9mm Guns?

“Do all 9mm bullets fit 9mm guns?” This is a question that pretty much every gun owner, from first-timers to aficionados, has probably asked themselves at some point in their lives. They may not have asked it out loud, though, since this is a frequent online search question. Maybe the relative anonymity of the internet is why you don’t hear it very often at the gun shops, shooting ranges, hunting camps, and gun shows where firearm folks congregate. The truth is, it’s a more complicated question than it seems to be.

You see, 9mm is a common blanket term that’s usually referring to one caliber of 9mm cartridge, not necessarily the 9mm bullet size. Once someone is looking at the caliber stamping on a gun vs. the print on a box of 9mm ammo, self-doubt sets in.

“Can I use 9mm Luger if I own a new Glock and not some old WWII gun?"

"What is 9mm Luger?"

"I don’t know what parabellum means!”

Take a few calming breaths, we’re going to provide you with the many different 9mm ammo types explained in a way that’s as easy to understand as possible.

Different Types of 9mm Ammo

There are at least 18 different cartridges that use a 9mm bullet. Many of those go by anywhere from two to four different official names, not counting the nicknames you’ll hear bandied about. There’s a lot of history to ammunition naming conventions that we’re not going to get into here, but for a more in-depth look, read “Bullet Sizes vs. Bullet Caliber, How Do They Name These Things?” To top it all off, most of the different 9mm caliber rounds aren’t even exactly 9 millimeters in diameter, since rounding up or down is pretty common. The most comprehensive and frequently updated resource of all calibers past and present is SAAMI (Sporting Arms and Ammunition Manufacturers' Institute), considered a standard reference for all things ammunition.

Getting the wrong rounds for your gun is a real headache. First off, due to safety reasons, nobody will accept ammo returns as there’s no way to prove they haven’t been tampered with and rendered unsafe. Second, and of more concern, you may find that you can chamber the incorrect rounds without a problem. However, when you actually fire them you’ll experience everything from jams to catastrophic failure. Catastrophic failures are as bad as they sound: it not only damages the gun but can cause serious injury or death to the shooter and/or bystanders. You may come across internet “experts” who say that you can shoot ammo through your gun that it’s not designed for, but “can” doesn’t mean “should” and this will inevitably lead to disaster. Stick with the markings on your gun and do a little research to ensure that whatever shells you end up buying are specifically for that gun. SAAMI also provides and updates a list of Unsafe Firearm & Ammunition Combinations if you’re ever in doubt.

These are the most common boxes of 9mm pistol cartridges you’re going to see when you’re shopping, in alphabetical order:

• 9mm +P
• 9mm Kurz
• 9mm Luger
• 9mm NATO
• 9mm Parabellum
• 9mm Short
• 9x17mm
• 9x18mm Makarov
• 9x19mm

5 of these are essentially the same thing, 3 of them are exactly the same thing with different names, and one of them is distinctly different. You may run across any of them at some point, especially when purchasing ammo whose country of origin is outside the U.S.

9mm Ammo Types Explained

When people talk about 9mm’s, they’re overwhelmingly referring to 9mm Luger ammo, not necessarily the famous WWII German semi-automatic 9mm Luger pistol. The name comes from Georg Luger, the Austrian who designed both. When it comes to 9mm Parabellum vs 9mm Luger, it’s exactly the same thing. If you’re wondering what parabellum means, it comes from the Latin Si vis pacem, para bellum (“If you seek peace, prepare for war.”), a pretty apt name for the most popular caliber of pistols and submachine guns used by militaries and police forces all over the world. 9x19mm is also the same thing, just going under a far more specific name. The 9 indicates the diameter of the bullet, and the 19 is the length of the case, both in millimeters. Hence, 9x19mm vs 9mm Luger is also exactly the same thing. For what it’s worth, the more exact cartridge dimensions of a 9mm Luger FMJ (Full Metal Jacket) are a 9.02mm diameter bullet, 19.15mm case length, and an OAL (overall length) of 29.69mm. A hollow point would be slightly shorter since the tip of the FMJ bullet has been sheared off when you look at it in profile.

We have 9mm NATO and 9mm +P ammo in the same family. What is a NATO round? It’s still the same 9mm Parabellum bullet in the same case length, but like 9mm +P it’s a hotter load, meaning it has higher pressures and therefore has greater velocity and energy than standard 9mm Luger rounds. For this reason, it shouldn’t be fired through a weapon that’s not rated for +P or NATO rounds. A quick check of the owner’s manual from the manufacturer will clear this right up. If you’ve inherited or purchased an old 9mm Luger pistol, you’re very lucky to have one. However, you shouldn’t fire any NATO or +P through it, as these older guns were never rated for the higher pressure.

9mm vs 9mm Luger: What Are Those Other Ones?

As we mentioned above, there are other 9mm pistol rounds that are not 9mm Luger/Parabellum/NATO/+P or 9x19mm. One of the most common is the .380 ACP. Wait, how did we jump from 9mm to .380? Interestingly, the .380 is actually another 9mm caliber, aka 9mm Kurz, aka 9mm Short, and most accurately the 9x17mm. You can add that to the other 17 or so 9mm calibers out there.

Another one to note is the 9x18mm Makarov. 9x18mm vs 9x19mm might seem like a tiny difference, but it’s enough to confuse people and will cause serious issues if they’re mixed up and loaded into the wrong gun. It’s the Soviet version of the 9x19mm Luger/Parabellum, essentially, and used commonly by militaries in the Eastern Bloc. Besides the difference in case lengths, the Makarov bullets are quite a bit larger. As previously mentioned, rounding off is a pretty common ammo naming convention. A Luger round has a 9.017mm diameter bullet, whereas the Makarov is a 9.27mm. It also only has about 60%of the pressure (psi) of the Parabellum, making it pretty weak in comparison.

Now You Know the "No" of 9mm's

Hopefully, we’ve explained the key differences in the most common 9mm ammunition you’re likely to encounter. As we said, you may well run across several different varieties, but as long as you’re using the appropriate ammo and being careful to make sure that you know how to read what’s specific to your gun, you should be fine. OpticsPlanet carries a wide variety of Ammo, including Handgun Ammo, and if you’re looking for what’s available to ship today you can skip right to the In-Stock Ammunition page and buy now!