Everything You Should Know About Pistol Cartridge Nomenclature

by
posted on November 4, 2019
** When you buy products through the links on our site, we may earn a commission that supports NRA's mission to protect, preserve and defend the Second Amendment. **
figure-3a-rimless38super.jpg (2)

Cartridge nomenclature can be confusing, as there has never been a standardized procedure for naming cartridges. Basically, pistol cartridge names have two parts. The first part of the name is a number, either in millimeters or in decimal inch measurements (known as caliber), that represents either the bullet or bore diameter (often only approximately). Sometimes there are two numbers—European cartridges in particular are designated by both the bullet diameter in millimeters and the case length in millimeters (e.g. 9x19 mm).

The second part of the designation is far more variable, and may represent any of several things: the name of the company responsible for the cartridge's development (.40 Smith & Wesson); the individual (.454 Casull) who originated or designed the cartridge; a popular or descriptive name (.38 Special); or, with military-designed cartridges, the firearm in which is was used (.455 Webley). A few cartridges have both decimal and metric designations, such as the .32 ACP and 7.65 mm Auto. FInally, some cartridges may be known by more than one name (9 mm Para, 9 mm Parabellum, 9 mm Luger and 9x19 mm).

For the pistol owner to select the proper ammunition for his or her firearm, all that is required is to match the designation on the barrel and/or slide with that on the cartridge box and the cartridge headstamp. If the barrel or slide of the firearm lacks a cartridge designation, or if there is a suspicion that the pistol may have been modified to fire a cartridge other then what is indicated by the markings, the gun should be taken to a competent gunsmith for an evaluation.

Lead photo by Brad Miller.


See more: Do You Know Advanced-Handgun Training Terms?

Latest

1 Lede
1 Lede

Six New Competition-Ready Optics for the 2026 Season

Six new optics from SHOT Show 2026 designed for competitive shooters, featuring quality glass, improved reticles and versatile mounting options across platforms.

SHOT Show 2026: Staccato HD C4X

Staccato’s HD C4X pairs a 4-inch compensated barrel with an aluminum frame, aiming to balance duty-grade shootability and everyday concealment in a compact 2011.

Benelli Updates Montefeltro Silver Semi-Automatic Shotgun Lineup

Benelli updates the Montefeltro Silver semi-auto for 2026 with engraved nickel receivers, AA walnut furniture, Inertia-Driven action and Crio chokes in 12- and 20-gauge models.

Winchester’s USA 250th Anniversary Ammo Puts History in a Box

At SHOT Show 2026, Winchester displayed its USA 250th Anniversary Commemorative ammo boxes with archive art and theme-matched loads in a limited run of 15,000.

WATCH: Fabarm Infinite RS Sporting

Fabarm’s Infinite RS modernizes the side‑by‑side with a quick‑release rib, competition fit and remarkable durability—see why in our on‑range video.

Best Of SHOT Show 2026: Top Suppressors

SHOT Show 2026 delivered a breakout year for suppressors, with 11 standout models showcasing advances in materials, modularity, durability and low back pressure performance.



Get the best of Shooting Sports USA delivered to your inbox.