Glock Gen Differences. The Complete Guide to Glock Generations 
What You Need To Know About The Glock Generations
Glock Gen Differences.
You might have heard something about different Glock generations as the company has periodically renewed, updated, and changed their pistols. Like anything else, incremental changes are made to the Glock platform to make it ostensibly better; and they usually are.
So, if you're wondering what the differences are between, say, a Gen 3 vs Gen 5 Glock, we're going to explain the difference.
By the end of this article, you should have a good idea of what it means when you see "Glock Gen Whatever" and understand what it means, especially if you were thinking of buying a Glock pistol…which is always a good call. So without further ado…
What Are The Different Generations Of Glocks? Why Does It Matter?
The Glock generations are the ongoing changes made to the design of the Glock pistol. Glock uses the term "generation" or "gen" to describe each successive one, i.e. Gen 3, Gen 5 and so on.
It's sort of like cars. Every decade or so, a new version of whatever car it is gets released on a new chassis design with other improvements. While the car is the same in many respects, a lot changes. For instance, the Ford Mustang is broadly the same size today as it was in 1963 and it's still a front-engine/rear-wheel-drive car…but today's Mustang is a lot different!
Why is it important?
In a lot of respects, it's not; it doesn't make for fun trivia and remembering where you put your car keys is much more important. However, there are some practical purposes for knowing what generation your Glock is.
For one, you have parts compatibility. Gen 3 parts are ridiculously common; Gen 4 and Gen 5 OEM parts are a little less common and a little more expensive. This also applies to aftermarket parts like triggers, sights, magazine wells, magazines themselves, and so on. Some OEM and aftermarket parts fit all Glock generations, others do not.
For two, that can also make getting holsters a bit of a pain depending on the model you get and whom you're buying the holster from.
Many Glock 19 holsters, for instance, will fit all generations; some will only fit up to Gen 3. Since the .40 S&W Glocks have some dimensional differences, a Glock 22 holster let's say will fit all the way up to the Gen 4 guns but not the Gen 5 guns which has been an issue for police departments who have to source duty holsters. Lucky for you, Alien Gear makes holsters right here in the USA that fit all Glock generations. You can find all of our Glock holsters here. Shameless plug aside, let’s continue…
Glock Gen 1
The "Glock Gen 1" is literally just the first generation Glock 17, the original pistol that Gaston Glock invented for the Austrian military. These are the rarest of all Glock pistols and oddly enough command something of a premium on the used market. The pistol was first released in 1984.
For those who don't know, the nomenclature for Glock pistols is the patent number. The Glock 17 was the seventeenth patent awarded to the Glock corporation. The fact that the gun held 17+1 rounds of 9mm is mere happenstance.
The original Glock 17 was a ruthlessly simple gun, with a pebbled finish on the frame, a smooth dust cover (nothing was getting railed at the time) and the standard Glock features like the trigger system, Glock sights, and polygonal rifling.
The original Glock 17 sold pretty well to police departments, militaries and to early-adopting civilians. The number in circulation are dwindling, so they have become something of a collector's item.
Part of the first generation was also the Glock 18, a full-auto 17 that was made in limited numbers for use as an SMG by some military and police units and as a stress test vehicle for Glock components. A compensated version - the 18C - was also devised.
Glock's Second Generation
The second generation of Glock pistols started with a number of minor design changes as well as the addition of the Glock 19 to the model lineup in 1988.
To make the gun more compliant with ATF regulations, a steel insert was added to the frame bearing the serial number.
The magazine design was revised to give the magazine additional spring tension, and the recoil system was changed in 1991 to a captive recoil spring (recoil spring and guide rod assembly) and the frame texture was changed to checkering rather than pebbling.
The Gen 2 guns also added the large frame models in .45 ACP and 10mm, as well as the Glock 22 and Glock 23 in .40 S&W. The Glock 24 - a longslide model in .40 S&W - was also released for competition shooters looking to make Major Power Factor, which cycled in and out of the product lineup.
Towards the end of the Gen 2 product cycle, the Glock 26 and Glock 27 pistols were released as backup guns for law enforcement and/or concealed carry pistols. The "Baby Glocks" as they were called were popular for both.
One of the last Gen 2 models to be released was the Glock 17C, which had barrel and slide porting.
Glock Gen 3
Glock Gen 3 pistols are - at the time of this writing - still in production and serve as the base models of all Glock guns regardless of caliber or frame size. The first of them were released in 1998.
Gen 3 improvements included raised texturing, finger grooves (some love 'em, some hate 'em) and the Universal Glock Rail on the frame for mounting a weapon light. An additional cross pin was added to the locking block for additional rigidity, and the design of the extractor was changed to serve as a loaded chamber indicator.
Tiffany Blue, FDE and olive drab were offered on select models as additional colors. Additional calibers, including .357 Sig and .45 GAP or Glock Auto Pistol, a .45-caliber cartridge with roughly the same case length as 9mm to fit the larger projectile in a 9mm frame.
Glock briefly offered the "Rough Textured Finish" or RTF trim on select models, which had revised stipling and texture on the gun and fish-scale slide serrations, but they didn't find many fans and were soon discontinued.
Glock's third generation also saw the introduction of the single-stack Glock 36 in .45 ACP, though the 10mm compact/subcompact model lineup did not get a single-stack option.
Part of the third generation of Glock pistol lineup was the addition of single-stack subcompact models for the US concealed carry market, specifically the Glock 42 in .380 ACP and Glock 43 in 9mm.
More longslide Glocks emerged as part of the Gen 3 models, including the Glock 34 and 17L in 9mm, as well as corresponding models in .40 S&W and other calibers. Longslide models of the large-frame Glock pistols, including the 41 in .45 ACP and Glock 40 in 10mm.
Glock Gen 4
Generation 4 pistols have few changes from the Generation 3 model guns, but have the addition of the Glock Modular Backstrap system. The GMBS, as it were, is swappable backstrap panels to customize the fit of the pistol to the shooter.
The first Gen 4 guns were introduced in 2010.
While the Gen 4 guns were initially marketed as the replacement for the Gen 3 guns, but that has changed. Currently, Glock only offers Gen 4 models on select guns to the public such as the large-frame Glocks and the .357 Sig models, but the 9mm and .40 S&W models are LEO only.
Besides the swappable backstrap panels, there are few differences between the Gen 3 vs Gen 4 Glock pistols that really add up to much worth talking about. However, some serious differences did emerge between the Gen 3 and Gen 5 pistols.
Slimline Glock Models
The Slimline models have features of multiple Glock generations.
Originally, the Slimline models were offered with a silver NVD finish on the slide (seen above!) but it was changed to Glock's standard black finish in the fullness of time.
The Glock 43X and Glock 48 pistols use essentially the same frame as a Glock 43, albeit with a longer grip housing for the Slimline magazine. Glock's magazine design - a polymer housing with a steel sleeve insert - makes these guns compact single-stacks, as the cartridges have to be stacked vertically rather than staggered.
The 43X slide and barrel are the same as the 43, just on a longer frame. The base 48 uses the same frame, but adds a longer (4.2 inches) barrel and slide. Like the Gen 5 models, the 48 and 43X are both offered in MOS (Modular Optic System) configuration, with a milled slide for mounting an optic.
The 43X and 48 MOS models both have a railed frame for mounting a microlight, and are milled for the Shield micro footprint. Glock also sells adapter plates for different optic footprints as well.
The Slimline Glocks exist in their own category, and as such bear separate mention.
Transitional Models: Glock 19X, 17M and 19M
There are a few "transitional models" that combine features from Gen 3, Gen 4 and Gen 5 pistols. In all cases, the design stemmed from a government contract - or gun made in a bid for one - that either did or didn't result in release on the civilian market.
The Glock 19X has Gen 5 features with a Gen 3 slide and frame. The 19X was Glock's failed bid for the US military's XM17 handgun trials, but was put on sale with some success. The gun includes the Glock Marksman Barrel and omits finger grooves (Gen 5 features) but otherwise has a Gen 3 slide, frame and small parts, and is wrapped up with an FDE finish.
The Glock 17M and 19M are government contract pistols made for federal law enforcement, and especially the Federal Bureau of Investigation. The 17M has Gen 5 features with a Gen 4 slide, frame and internals, including the omitted finger grooves, a flared magwell and the Glock Marksman Barrel. The 19M is the same, just in a compact.
However, the 17M and 19M were never (and aren't going to be) offered for civilian sale.
Another interesting model that occupies its own space is the Glock 46, a pistol made to satisfy contract requirements of various German police agencies. It has been adopted by state police of Saxony-Anholt (in eastern Germany) but otherwise is little more than a curiosity. Curious, however, it is; the 46 has a rotating barrel (a la the Beretta Cougar/PX4) and a manual safety as part of the requirements. It is not likely to be offered for civilian sale.
Gen 5 Glock Pistols: Continuing Evolution
The Gen 5 Glock pistols had the most significant updates. Some argue they are the best guns the company has made to date.
The first significant update was the Glock Marksman Barrel. Glock had made much ado about their polygonal rifling, a rifling pattern that few other gun companies employ. A certain amount of the gun-buying public insisted it made the guns more accurate, but competent shooters who actually shot their Glocks at distances beyond 5 yards often found otherwise.
A B8 at 25 yards is a harsh mistress and has revealed many factory pistols to be lacking for accuracy. One of the most common aftermarket upgrades for Gen 3 Glock pistols (it should be said) is a match barrel. We call that a clue. Glocks haven't really been a mainstay for champion NRA Bullseye shooters. That is also a clue.
The GMB is button rifled - like most barrels are - and as a result, the Gen 5 guns have been noted to be far more accurate at longer distances.
The frame and slide were also beefed up, typically increasing slide and frame width by 0.1 inches. The Glock 19, for instance, swelled from 1.26 inches at the frame to 1.34 inches, so the guns have gotten a little chunkier.
The trigger system components were also changed, giving the gun a harder wall and - many feel as a result - a better trigger pull.
The Gen 5 guns also add front cocking serrations (muh press checks) to the slide. The frame texturing is revised, and the Gen 5 guns also come with swappable backstraps and a slightly flared magwell. The finger grooves - to the delight of many - are removed.
Many Gen 5 guns can be had with the Glock MOS slide cuts for mounting an optic. The MOS models on the non-Slimline models are only for use with adapter plates; the slide is milled for MOS plates rather than a particular optic footprint.
The fifth Glock generation also saw the introduction of the Glock 45, which is essentially a 19X just with all Gen 5 features.
Another curiosity is the Glock 47, which is not offered for sale but is manufactured by Glock for the US Border Patrol. The 47 is a Glock 17 MOS slide on a Glock 45 frame, so it's not supremely unique by any stretch.
Gen 5 models are not being offered in all calibers. So far, they are restricted to 9mm and .40 S&W.
Glock Gen 3 vs Gen 5, Glock Gen 3 vs Gen 4: Which Glock Is Best?
Which Glock generation is "best" is subjective, although there are a few features and design details that do make some better than others.
In the broad strokes, the Gen 5 guns are going to be "better" in many regards if you were weighing a Glock Gen 3 vs Gen 5 pistol. The barrels are better on the Gen 5 guns, the trigger is better, you can get a MOS model, swappable backstraps are cool, and some people find the finger grooves annoying.
A lot of people consider a Gen 3 as a starting point. If you want the best out of them, you have to invest some time and money into improving it. The Gen 5 guns are widely considered to need a lot less work.
The idea is the Gen 5 guns are probably the best they make. However, if your needs or wants in a handgun are very basic - ie you just want a workhorse pistol and don't care about the niceties - the Gen 3 Glocks are hardly going to let you down in any way and are a bit cheaper.
Granted, then Gen 5 guns are only offered (for now) in 9mm and .40 S&W. The big-bore Glocks are Gen 3 or Gen 4.
As far as Gen 3 vs Gen 4 guns, the Gen 4 models add the swappable backstrap panels (and little else) but that can make a difference to some shooters. It's also the case that some guns - such as the Glock 40 in 10mm or Glock 41 in .45 ACP - are only optic-ready in Gen 4 trim.
So ultimately it's whether the features of each generation are worth it to you, and that's something only you can answer.
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Gen 5 model 45 fails frequently