Ammo Calibers for Concealed Carry

Handgun ammunition is available in dozens of standard sizes known as calibers. Each gun is designed to fire a particular caliber and cannot fire other sizes. For semiautomatic pistols the five most popular are shown above from smallest to largest:

• .22LR (twenty-two caliber)
• .380 ACP (three-eighty caliber)
• 9mm (nine millimeter)
• .40 S&W (forty caliber)
• .45 ACP (forty-five caliber)

These five together account for over 99% of semiauto pistol sales that are sized for the concealed carry market. The number in each name refers to the diameter of the corresponding gun barrel. In the list above, each diameter is designated in inches except for 9mm (=.354 inches). Note that 9mm ammo has a slightly smaller diameter compared to .380 ACP but it is longer and packs more power.

By far the most popular handgun caliber is 9mm, including for the market of concealed carry pistols. It is also commonly known as:

• 9mm Luger, named after Georg Luger who designed this ammo back in 1901 specifically for military applications.
• 9mm Parabellum, as originally named by Luger – it means “for war” in Latin.
• 9mm NATO, since it is a standard caliber for NATO forces.
• 9x19mm, since 19mm is the standard length of the casing. There are a few other 9mm calibers with different specs (e.g. the 9x18mm Makarov), but 9x19mm is by far the dominant caliber so it is the only one called ‘9mm’ for short.

9mm has been selected as the standard pistol caliber by the US military, NATO, special operations forces, CIA, FBI, secret service, and most police departments. The reason for this widespread adoption is the balance between size and stopping power.

9mm rounds are capable of providing adequate stopping power in the majority of defense situations. Larger calibers have even more stopping power but they impart more recoil. Higher recoil will diminish a shooter’s combination of speed and accuracy when firing multiple rounds since it takes longer to get the sights back on target between each shot. Recoil becomes harder to manage for guns of lower weights, so recoil is an important factor to consider in firearms that are sized small enough for concealed carry.

Additionally, selecting a larger caliber limits how many rounds can be carried per size and weight of the firearm. The cost per round of ammo is also higher for larger calibers. 9mm is the sweet spot for semiauto pistols and dominates the markets for military, police, home defense, sport shooting, and concealed carry. For carry guns, 9mm models outsell all other calibers combined.

Next Topic: 9mm Ammo Manufacturers