Here at AT3, we get a lot of questions about GLOCKs and accessories. It makes sense–understanding the nuances between different GLOCK models isn’t easy. That’s why we’re putting together this GLOCK buyer’s guide.

The Basics

GLOCK. There are a handful of surnames that have crossed over from the firearms industry into the common American idiom: Colt, Smith (and Wesson, too), Winchester, and Browning. Glock, though, spread fast.

When Austrian Gaston Glock built his now ubiquitous pistol design, many in the industry were dismissive of its reliance on a polymer frame. Few believed the design would stand up to the punishment of live fire. Plastic, they said, would melt.

And Americans wouldn’t buy a plastic gun, right? Silly Gaston.

That was then. Now GLOCK is a household name.

Even so, understanding GLOCK’s naming system can be complicated. All the pistols look strikingly similar. While there are some that come in different colors, almost all of them are black with the same basic shape to the grip and the same squared-off slide.

Don’t miss it... Sign up to get US Army Service Manual for AR-15!
Please enable JavaScript in your browser to complete this form.

Glock numbers

And they all have numbers. These are sequential, in the order that they were released. There’s no predictability in this system, either. They skip around in the common calibers.

The higher the number, the newer the GLOCK. So, a GLOCK 48 came out much later than a GLOCK 19. AT3 sells GLOCKs, and you can see through our available inventory here.

The numbers are important. This is why gun models are often abbreviated as “G19” or “G48.” The most iconic of these are often shortened to just numbers, like the 43 or 19.

Glock 48 Silver 9mm Compact Pistol – 10 Round – 2 Magazines
GLOCK was late to the two-tone game, but now a few–like this G48–come with a new look.

GLOCK generations

Guns rarely leave the catalog. While some wain in popularity (usually because a new model makes the old gun somewhat obsolete), most will get period generational upgrades. In some cases, these upgrades fix specific known issues with performance. Most often, though, these generational upgrades change textures on the grips.

In some instances, like the G19, there will be very small exterior changes to the gun. Gen 1, 2, and 3, G19s are not always compatible in holsters made for Gen 4 and 5 G19s. The Gen 4 changes shortened the overall length and length of the trigger pull and changed the texture.

It takes an aficionado, though, to spot different generations from any distance.

Glock G43X Subcompact Pistol - 9mm/10 Round UX4350201 - USA Made
The G43 holds 7 rounds. The G43X, pictured, ups that to 10.


GLOCKs in the United States are sold in eight calibers: .22 LR, .380, .357 SIG, 9mm, .40 S&W, .45 ACP, .45 GAP, 10mm. The caliber is not reflected in the model number. And there’s not a compatible model in each corresponding caliber, either. Most common calibers, though, have a standard size (others call this full size or duty size), a compact (which is not all-that compact), and subcompacts. Some include longer versions that are classified as competition size.

.22 LR

  • G44–The .22 LR GLOCK has a 4.02″ barrel. This compact is a perfect addition for those who want to train with less expensive ammo.
The G44 looks like other GLOCKs, but it is a .22 LR.
The G44 looks like other GLOCKs, but it is a .22 LR.


  • G42–The G42 came before the 9mm G43. The subcompact has a 3.25″ barrel and a single-stack magazine.

.357 SIG

  • G31–The 4.49″ standard length G31 is chambered in .357 SIG–a fast round that has increased range.
  • G32–The G32 is the compact .357 SIG. The shorter 4.02″ barrel strips off some of the .357 SIG’s velocity.
  • G33–The G33 has a 3.43″ barrel, and a super short grip. The subcompact has a double-stack magazine, though, that holds nine rounds.
Glock G19 Gen3 Pistol with 2 15 Round Magazines - 9mm/15 Round GL1950203
Many feel the G19 has the best balance of functionality and concealability.


  • G17–The G17 is iconic. This standard-sized 9mm has a 4.49″ barrel, holds 17 rounds, and was the GLOCK that started it all in the US.
  • G17L–There are many versions and generations of the G17, but the G17L has the longest barrel:6.02″.
  • G17 MOS–The G17 MOS is another twist, and is optics ready.
  • G19–The G19 has a 4.02″ barrel. This compact design is arguably the most popular handgun in the United States.
  • G19 MOS–The G19MOS, like the other MOS pistols, add the ability to accept optics on the slide.
  • G19X–The G19X is essentially a G17 frame with a G19 slide. This adds capacity to the magazine and extra control surfaces. The gun was the first factory gun from GLOCK to come in FDE.
Glock 26 Gen5 9mm Sub-Compact Pistol – 10 Round – 3 Magazines
The stubby G26.
  • G26–The G26 is a subcompact with a 3.43″ barrel, a 10 round magazine, and a stubby grip. While smaller than the G19, the G26 is just as wide.
Glock 34 Gen5 MOS 9mm Pistol – 17 Round - 3 Magazines
The G34–a long slide for accuracy.
  • G34–The G34 was built for accuracy. The 5.31″ barrel on this “competition” sized GLOCK allows for a longer sight radius, too, which can improve accuracy.
  • G34 MOS–Most competition pistols today are topped with a red dot optic, and the G34 MOS is set up for that task.
  • G43–The G43 was GLOCK’s first single-stack 9mm. With a 3.41″ barrel, this subcompact remains one of the most popular concealed carry pistols around.
Glock G43X Subcompact Pistol - 9mm/10 Round UX4350201 - USA Made
The GLOCK 43, despite it being a single-stack, is still hugely popular.
  • G43X–The G43X is another hybrid design. This one combines the G43’s slide with the frame of G48, giving it 10 rounds in the magazine.
  • G43XMOS–For ten rounds of 9mm and an optics-ready slide, check out the G43 MOS.
  • G45–The G45 is very similar to the G19X. The size is identical–a compact with a 4.02″ barrel. The main difference is that the G45 is black like most of the other GLOCK pistols.
  • G45 MOS–Keeping the trend going, the G45 MOS is optics ready, from the factory, making for an even more versatile 9mm.
Glock 48 Silver 9mm Compact Pistol – 10 Round – 2 Magazines
The GLOCK 48, in two-tone black and silver.
  • G48–The G48 is a compact single-stack. With a 4.02″ barrel and 10 round magazine, this is a bridge between the G43 and G19.
  • G48 MOS–The G48 MOS is a slim compact single-stack that is optics ready out of the box.
  • G45 P–The G45 P is essentially an inert G45 that is a distinct color and built for training purposes. The P stands for practice.
  • G17 P–The G17 P is designed for safe training use. These practice guns are identical to their live-fire counterparts, only a bright and unusual color of reddish-pink.
Glock 22 Gen3 40 S&W Pistol – 10 Round - 2 Magazines - 3
The G22 is a .40 S&W that is almost identical to a G17.

.40 S&W

  • G22–The G22 is a standard 4.02″ barreled .40 S&W. This gun is the same size as the G17, but the .40 has a bit more punch.
  • G22 MOS–The G22 MOS provides optics-ready performance from the factory.
  • G23–The 3.44″ barrel makes the G23 compact. This gun is another that has been popular with government agencies that wanted something more powerful than the standard 9mm.
  • G23 MOS–The G23 MOS is a compact .40 S&W built with the ability to accept optics.
  • G24–The G24 takes the .40 S&W into its long slide configuration. At 6.02″, this is a long GLOCK.
  • G27–The G27 is the short, stubby .40 S&W. This subcompact has a 3.43″ barrel.
  • G35–GLOCK builds a .40 S&W competition model, too–the G35. This one has a 5.31″ barrel and long sight radius.
  • G35 MOS–While .40 S&W is not a popular competition round, the G35 MOS has found favor with specialized law enforcement groups that need the speed of red dot optics and enhanced accuracy.
  • G22 P–Like the other bright practice pistols, these are built for those who actively train with a safe gun. The G22 P is an ideal practice pistol for anyone who carries a G22.
  • G23 P–The G23 P is the same concept–built for a one-to-one practice gun.

.45 ACP

  • G21–The barrel on the G21 is 4.61″. This makes for a solid GLOCK .45 ACP that pulls more speed from the fat, slow rounds. The G21 is in the standard family.
  • G21 SF –As the .45 ACP is almost half-an-inch wide, the slide on most of the GLOCKs in this caliber are wide, too. The SF mods don’t alter the width there, but they do take out some of the width of the grip making the G21 SF easier to use for those with small hands.
  • G30–The G30 is a handful, and nothing more. This .45 ACP runs from a 3.71″ barrel, but it sacrifices grip length in order to be more easily concealed. This subcompact is a good choice for those running a G21 as a primary gun.
Glock 30S Gen3 45ACP Sub-Compact Pistol – 10 Round – 3 Magazines
The .45 ACP G30S.
  • G30 S–The G30 S has both a short frame and a slim slide. The width of the slide is .2″ thinner, roughly, but the overall width of the frame remains the same.
  • G30 SF–The wide range of options can get confusing. The G30 SF is not a slimmed slide gun but a narrow grip version. Each of these minute changes makes a difference, though, in how the guns perform for certain shooters.
  • G36–The G36 is the compact version of the .45 ACP GLOCK. The barrel is 3.78″ long. Magazine capacity, though, is just 6 rounds.
  • G41–The competition length G41 has a 5.31″ barrel and a magazine capacity of 13 rounds.
  • G41 MOS–The G41 MOS takes the competition functionality of the G41 to the next level by adding the option for red dot optics to long slide and higher capacity.

.45 GAP

  • G37–The G37 has a standard classification and a barrel that’s 4.49″ long. It holds 10 rounds of .45 GAP (GLOCK Action Pistol)–a shorter version of the .45 ACP that was specifically built for use in GLOCKs.
  • G38–GLOCKs .45 GAP compact has a barrel length of 4.02″. The mag capacity is 8 rounds.
  • G39–The G30 is a subcompact with a 3.43″ barrel, super short grip, and a magazine capacity of just 6.


  • G20–Those looking for more power will love GLOCK’s 10mm guns, especially the G20–the standard, 4.61″ 10mm. And magazine capacity is solid, too, at 15 rounds.
  • G20 SF–The G20 is a big pistol, so GLOCK has made an SF version that slims down the grip for those with smaller hands.
  • G29–While the 10mm is not usually considered in most discussions of concealed carry calibers, GLOCK makes the subcompact G29 that has a short grip, reduced capacity, and barrel length of 3.78.
  • G29 SF–If the G29 is hard to wrap your hand around, try the G29 SF. This is cut to allow smaller hands access to the controls.
  • G40 MOS–For those looking for the ultimate pistol for bear country, the G40 MOS has a 6.02″ barrel and the ability to accept red dots with little modification. While this is billed as a competition gun, it is capable of so much more.

GLOCK abbreviations

Gen means generation. Most of the time, when a new generation is released, the old generation fades away. In some cases, though, two generations of the same design might remain in the catalog.

Glock G45 Gen5 MOS Pistol - 9mm/17 Round PA455S203MOS
The slide on a MOS GLOCK comes with a cover plate installed.

MOS means Modular Optics System. This is the optics-ready factory option from GLOCK. They’re the same as the other models, but the slide and its adapters make mounting micro red dots much easier.

A GLOCK 21 SF. It is hard to see, but the grip has a thinner circumference.
A G21 SF. It is hard to see, but the grip has a thinner circumference.

SF means short frame. This one is a bit tricky, as the frame itself isn’t really what’s being addressed. Instead, it is the grip. The grips on SF pistols have been thinned out to reduce the amount of grip small-handed shooters have to hold. On longer grips, the SF mod reduces the palm swell and brings the back of the grip more toward the lines you find on the front of the grip.

S is for the slimmed slide. This is what it sounds like. Wide slides that can be thinned out for better concealment may get the S treatment.

The P means Practice, not Pink.
The P means Practice, not Pink.

P is for a Practice gun. These aren’t pink, exactly, but not red either. They’re a strange salmon color and are designed for doing holster work and training safely.

Glock G45 Gen5 MOS Pistol - 9mm/17 Round PA455S203MOS
The G45 is essentially a G17 frame, with a G19-length slide and barrel. The result is a compact with a full-size grip and magazine.

X is the last distinction of importance. The X typically denotes a crossover pistol. Take a G19 slide and put it on a modified G17 frame (for the added grip length and capacity of a G17 and the shorter length of the G19). But the G45 pistols are built in a similar fashion but don’t have an X designation (even though GLOCK still labels them as crossovers).

What makes a GLOCK a GLOCK?

We’ve discussed polymer. That’s important. They don’t have the best grip texture or the most aggressive texture, yet they’re easy enough to control.

The barrels don’t use traditional lands and grooves. Instead, they’re cut with polygonal rifling, which is essentially wider flat panels that approximate a circular shape inside the barrel.

Glock OEM 10 Round Magazine for G19 - 9mm
Part of GLOCK’s success is the way they make these magazines. They rarely ever fail.

GLOCK mags are built like tanks. They’re stainless with a polymer wrap and can take a serious beating without losing any of their functionality.


As noted above, GLOCK makes some of the standard sizes: subcompact, compact, and standard (which is a full-size or duty size for other manufacturers). They also make long-slide models.

One interesting note is that the company still hasn’t made a super-slim 9mm double-stack. The 43 made waves when it was released, as the G26 has always been a fireplug of a subcompact. But the 43 has dismal capacity when compared to almost every other pistol in its class. The 48 improved on that capacity, but only by adding length to the grip.

GLOCK Accessories

There’s no denying the versatility of these pistols. But there are ways to make them more functional. The first addition, if you have a MOS GLOCK, is to add a red dot.

The ARO on an MOS equipped GLOCK is a solid choice for getting on target fast.
The ARO on a MOS-equipped GLOCK is a solid choice for getting on target fast.

The AT3 ARO is a great choice. Put the dot on the target and you’re good to go.

Have a GLOCK 17 or 19? Magpul can help there, too.
Have a GLOCK 17 or 19? Magpul can help there, too.

You will need magazines. GLOCK mags are a solid choice, but so are those by Magpul. How many magazines do you need? 10 is a good place to start for a GLOCK.

Streamlight TLR-1S Tactical Light - 300 Lum - Strobe
Trying to identify a target in the dark is all but impossible without light.

Lights are also a good choice. Most GLOCKs have small sections of rail that accept lights that attach to Picatinny rails. If there’s one accessory that you need–one that will radically expand the performance of a pistol, it may be a good light. The Streamlight TLR-1 is a 300-lumen option that will fit on many GLOCKs.

One Last Tip

If there’s anyone that knows the AR-15 platform, it’s the US military. As a special offer for our readers, you can get the Official US Army Manual for AR-15/M4/M16 right now – for free. Click here to snag a copy.

Read More

1 thought on “The GLOCK Buyer’s Guide

  1. Forwarding…

    “Glock Models Explained”

    So Glock just announced their new Glock 44, chambered in 22 rimfire. I figured now would be a good time to explain Glock and their models….

    The Glock 44 is in 22.

    The Glock 22 is in 40.

    The Glock 40 is in 10 like the 20.

    There is no Glock 10, but there is a Glock in 9 aka the 17 and 19 and 26 and 43, not including the 48 – which came out before the 44 – and the 43X, which are the same except for the ways in which they’re different.

    Actually they’re like the 45, which is a 9, which is the same as a 19x which is actually more like the 17 than the 19. Strangely enough the 45 came before the 44, but 45 came before 9, but not 44, so maybe that’s the logic.

    If you wanted a 45, you need a 36, a 41, a 30, a 21, or a 21SF, or a 30S, or a 30SF. Of course if you want Glock’s 45 you need a 37, 38 or 39. The 38 isn’t a 38, there are other 38’s.

    If you want a Glock, definitely get the 19 and maybe a 22 to practice with – not the 40 22, but the 44 22. The 22 won’t help you to practice with your 9 as much as a 23, which is closer to the 19. Unless your goal is competition, in which case you should have been considering a 35 or 17L or 24 or 41 or 34 which are 40 9 40 45 9 respectively.

    The 31 32 and 33 are actually 357’s but not the 38 357’s. They’re 357’s that are more like 9s but not like the 380 is like 9’s. If you wanted that you need a 42. And nobody likes a 42, you’re better off with a 9. And therefore try a 44 because everyone loves to work on their 9 with a 22.

    Edit: Glock if you read this I want a 44 but not a 22, that is I don’t want a 22 at all but I want a 44 because I’m already into the 22 and I’d prefer a 44 to a 22. Also please make a 50 that is a 17 22 or a 22 22 and make a 49 that is a 50. Thank you.”

Leave a Reply

Your email address will not be published. Required fields are marked *