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Pistol Magazines: The Ultimate Guide

Image of Bryan Hill, Founder of Pistol Wizard Bryan Hill / March 21 2024

Diagram showing where the magazine is on a Glock 19, plus a closeup shot of a pistol magazine

We're going to cover the basics of pistol magazines, dispel myths with data and case studies from real self defense shootings, and help you decide whether to upgrade your magazines or choose a pistol with bigger ones.

Basics

Pistol magazine assembled vs. disassembled

^{Left: Magazine with ammo. Right: Disassembled magazine.}

A pistol's magazine (mag) holds ammunition (ammo). They're simple in design:

A box, to contain everything and fit in the gun.
A spring, to push ammo up as you fire the gun.
A follower, to put ammunition on.
A baseplate to hold it all together.

Magazine Types

Single-stack: each round of ammo rests on top of each other.

Found in most pocket pistols and older larger pistols.
Double-stack: each round of ammo is staggered in two columns.

Found in modern compact and full-size pistols.
Hybrid: A balance between the two.
Found in the Sig p365 and Springfield Hellcat.

How do you tell which kind is which? Look at the top of the magazine with a few rounds inside. Here's a real single-stack on the left, and double-stack on the right:
Single-stack vs. double-stack magazines: closeup comparison of how to tell which is which

Single-stack vs. double-stack magazines: closeup comparison of how to tell which is which

What to Look for in a Magazine

Reliable. Before purchasing a magazine, check reviews to see if it causes jams or if it runs reliably.
Concealed carry: Not too long. When carrying concealed, the grip prints the most. The more your magazine extends past the pistol's grip, the less compatible your pistol is with any given outfit. Pocket pistols may no longer fit in your pocket at all!
Pocket pistols: Not too short. Some pocket pistols have a grip so short that you can't get your pinky finger around it. Extended magazines can let you get a full grip on the pistol, while also granting more ammo capacity.
Loads easily. Some magazines are harder to load into the pistol than others. Mec-gar magazines use a special coating that makes them easier to load.

My Magazines Don’t Fall Freely From the Gun. What to Do?

Wipe each side of the mag once with a silicone towel:
Birchwood Casey Silicone towel cloth

If that doesn't do it, wipe inside the pistol's grip.

Can I Store My Magazine Loaded?

Yes. The magazine spring weakens over time mostly from loading and unloading the last 1-2 rounds. Once they're loaded, it doesn't weaken the spring any further. If you load your mag to 1 less than its capacity, its spring will last longer and cause fewer jams.

Are Pistol Magazines Interchangeable?

Rarely. Glock magazines are mostly interchangeable as long as they're the same caliber, except for their pocket pistols (G42 and G43).

Company	Model	Caliber	Interchangeable with Glock 19 Mags?
Glock	17	9mm
Glock	34	9mm
Glock	43	9mm	No; pocket pistol uses different mags
Glock	20	10mm	No; Glock 10mm mags are different from 9mm mags

For other companies, the pistol must be of the same line and caliber. For example, CZ P-10 F magazines are interchangeable with P-10 C and P-10 S pistols, but not the CZ 75 series.

Company	Model	Caliber	Interchangeable Mags with CZ P-10 C?
CZ	P-10 F	9mm
CZ	P-10 S	9mm
CZ	75	9mm	No; CZ 75 series uses different mags from CZ P-10 series.

Magazine vs. Clip

A clip is just a piece of metal that holds ammo together. There's no spring, box, or follower:
Side and back view of an ammo clip: A piece of steel shaped to hold rounds of ammo together.

Side and back view of an ammo clip: A piece of steel shaped to hold rounds of ammo together.

Clips can load ammo into a magazine, or a gun's internal magazine. Here's a Mauser C96, being loaded with a clip, and then a magazine:

Clips are common on rifles designed in the early 1900s:
A Yugo M48, one of the last rifle designs to use clips instead of magazines. It was invented in 1950.

A Yugo M48, one of the last rifle designs to use clips instead of magazines. It was invented in 1950.

A clip might load a magazine, but a magazine can't load a clip. Modern guns use magazines, not clips.

What is Magazine Capacity?

How many rounds of ammunition it can hold. A 15-round mag holds 15 rounds of ammunition. You could fire it 15 times before needing to reload.

How Many Rounds of Ammo Do I Need?

In a gunfight, a jam is often fatal.

Running out of ammo is a jam you have control over. Do you want a jam at 17 rounds? 15? 10? 7?

How many rounds do you think you need to stop the threat?
How good is your accuracy under stress?

Let's look at some real-world examples to get an idea. This defender had 15 rounds:

This defender had 6 rounds:

In those cases, they each had enough capacity to defend their homes and their lives. Are these examples just cherry picked? Let's check some data:

Tom Givens, a firearms instructor, has 65 Students who have been in gunfights. All those who were armed at the time prevailed. Most of them fired 3-4 rounds, but at least three accounts involved 8, 11, and 12 rounds fired.
Claude Werner collected 482 self-defence incidents, and found that on average, defenders fired 2 shots, but the most anyone shot was 20 times. Defenders only reloaded in 3 incidents. 36% of incidents involved multiple attackers. Usually, it was 2 attackers, but there was an incident with 7 attackers.

Averages can be deceiving. Do you think 2-3 rounds is enough against 7 attackers? How about 4?

Burglars and robbers usually run after taking fire. But do you want to prepare against "the average", or the worst historic examples? As of this writing, No one has ever come away from a gunfight and said, "I wish I had fewer rounds".