There's a false distinction between 9mm, 9mm Luger, 9mm Parabellum, and 9x19mm ammunition. As we straighten out the misconceptions, we'll also explore some of the most commonly used 9mm ammunition and a few of its top uses.

9mm Versus 9mm Luger

The term “9mm” and “9mm Luger” are often mentioned when discussing firearms and calibers, but what exactly do they mean? Understanding the ins and outs of ammo can be daunting at first, but having a well-rounded knowledge about firearms can be advantageous. It is always good to know what you’re talking about when it comes to firearms and their metal-jacketed counterparts.

‘9mm’ refers to the caliber, or size of the round. Specifically, it refers to the diameter of the bullet. The larger the measurement, the stronger the round (usually). 9mm is on the smaller end of the spectrum, but .22 caliber is slightly smaller. (There are some round sizes that are even smaller, but the .22 is about the smallest commonly used caliber.)

In reality, there are dozens of types of 9mm ammo. 9x19mm, .380 ACP, .38 Special, and the 9x18mm are all members of the 9mm family, but each one has its own applications. With so many different kinds, let’s dive into a few of the more common cartridges.

9x19mm Caliber

The 9x19mm caliber is by far the most commonly used. As a solid baseline for handgun ammo, this variant of 9mm is affordable, versatile, and fits a variety of popular firearms, including the Glock 19, Springfield XD, and the Sig Sauer P320. This type was first produced in 1902, and has since made its way to the top of the 9mm pecking order.

The .380 ACP, 1911’s Soulmate

Alternatively the .380 ACP is less commonly used, but still a solid choice for small handguns. ACP stands for “Automatic Colt Pistol”, and it refers to the first kind of firearms that were chambered for this ammunition. Though its name is a bit deceptive, this cartridge falls into the 9mm family, having a 9mm caliber and a 17mm length. It’s the little brother of the .38 ACP, whose name definitely doesn’t make these two cartridges confusing at all. This one is a solid caliber for self-defense. Slightly younger than the 9x19mm round, the .380 ACP was first produced in 1908.

What’s So Special About .38 Special?

The .38 Special is a tried and true revolver cartridge. This one has been around since 1898, and isn’t heading into antiquity anytime soon. Like the .380 ACP, its name doesn’t communicate its 9mm caliber, but it sits at a measurement of 9x29mm. It is still one of the most popular calibers for revolvers, and finds use as a target practice round, competitive shooting round, and small game hunting round. Though the name might imply it, there is no “.38 Ordinary.”

From Across The Sea - Makarov

In terms of length, the 9x18mm Makarov cartridge sits between the .380 ACP and the 9x19mm. Compared to the .380 ACP, this 9mm is very similar. One of the key differences is in power: the Makarov can pack a punch as strong as 23,500 psi, while the .380 ACP maxes out at 21,500 psi. As a cartridge of European origin, many of the handguns that are chambered for 9x18mm are, you guessed it, European firearms. The Makarov PM, Grand Power P9M, and the Fort 12 are all chambered in this round, which was first introduced in 1951.

Summing Up

For a newcomer to firearms, the plethora of terms that include ‘9mm’ might be overwhelming, or just plain confusing. The truth is, many of these terms all refer to the same kind of cartridge. “9mm”, “9mm Luger”, “9mm Parabellum”, and “9x19mm” all are used interchangeably to refer to the same thing.

The Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) refers to this caliber as the 9mm Luger, and since the Institute pretty much calls the shots for the firearm world, “9mm Luger” is technically the most accurate name for these rounds. However, that doesn’t stop enthusiasts from calling them 9mm Parabellum, 9x19mm, or just plain 9mm rounds. Just know that whenever an individual uses one of these terms, they are most likely referring to the 9mm Luger type cartridge.

But what about all the other 9mm rounds out there? Don’t they get a special four-in-one deal for names? Perhaps when a new 9mm cartridge dethrones the 9x19mm as top dog, there will be a swarm of new and confusing terms to refer to it, but until that happens, the 9mm Luger will sit with its four confusing and interchangeable names.