Glock 31 GEN4 Review

Originally founded in 1998, the Glock 31 was the first of the Austrian arms maker’s polymer- framed semi-autos designed for the new .357 SIG cartridge, which was produced in the U.S. by munitions designers Michael Bussard & Alan Newcomb in 1994 as an alternative high-powder cartridge for law enforcement use. Bussard explains, “When American law enforcement agencies found the 9mm lacking in ballistic show, this cartridge was conceived by the artists as a quick, easy solution to the problem. While several big law enforcement agencies use this cartridge, it remains something of a police specialty.”

The .357 SIG is a .40 cartridge case necked down to 9mm. This presents the additional internal volume for more large powder charges & higher muzzle velocities than the classic 9mm. The .357 SIG is usually loaded with a 124- to 125-grain bullet, & despite its nomenclature, the .357 SIG uses 9mm (0.355-inch diameter) rounds.

Glock 31 Specs

Caliber / System

.357 – Safe Action


Height: 138 mm / 5.43 in.
Length: 204 mm / 8.03 in.
Barrel Height: 32 mm / 1.26 in.
Width: 30.00 mm / 1.19 in.
Barrel Length: 114 mm / 4.48 in.
Length Betn Sights: 165 mm / 6.49 in.


Loaded: 940 g / 33.18 oz.
Unloaded: 740 g / 16.12 oz.
Trigger Pull: ~2.5 kg / ~5.5 lbs.
Trigger Pull / Travel
Trigger Travel: ~12.5 mm/ ~0.49

Barrel Rifling / Length of Twist
Length of Twist: 250 mm / 9.84 in.
Barrel Rifling: right hand, hexagonal
Magazine Capacity –
Optional: 10 Standard: 15

Gun Details

The latest Gen4 variant of the Glock 31 brings better handling & versatility to this already well- established sidearm. The gun now has an adjustable fit for hands of-of various sizes through Glock’s innovative, interchangeable full-length backstrap panels, & a larger, more comfortable to use magazine catch. The G31 is a st&ard-sized Glock design. The .357 SIG model is also available in the market compact G32 & subcompact G33 versions, the latter ideal for concealed carry & as a backup gun.

The full-sized G31 measures 7.95 inches with the st&ard backstrap, 8.03 inches with the medium backstrap, & 8.11 inches with the large panel in place. Changing the backstraps adjusts the distance to the trigger from 2.76 inches to 2.83 inches, & 2.91 inches, respectively.

This is an all-important characteristic for the Gen4 version of the .357 SIG, as recoil management is necessary with this hard-hitting defensive cartridge. The G31 Gen4 also applies Glock’s new double recoil spring/ model rod design to help relieve muzzle flip. There is also a ported-barrel version for enhanced stability & accuracy, the Glock 31C Gen4.

  • ]Like the other Glock Generation 4 models, the Glock 31 offers some enhancements to the Glock 31 Generation 3:
  • As noted in the Glock 17 Gen 4 review, the new magazine release button is significantly enlarged. While a apparently minor change, it makes a huge difference in usability. Ease of dropping a Glock magazine is much improved. The magazine release button is also reversible.
  • The Glock 31 Gen 4 too interchangeable grip backstraps with three size options, allowing the buyer to customize fit to their specific hand size.
  • The recoil spring assembly is a two-part spring. While we did not discern any difference in functionality from the single spring Glock Gen 3 models, Glock claims that the latest spring assemblies will offer long life cycle & reduced felt the recoil. The Glock 31 is indeed a soft shooting gun, but we were only able to compare felt recoil to a G32 Gen 3, which is not an apple to apple comparison gave the smaller size & lighter weight of the Glock 32.
  • Also like other Gen 4 models, the Glock 31 Gen 4 features a new & improved grip texture. We like the modern feel. While personal preference rules & your opinion may vary, ours is that no grip tape, stippling, or another type of grip enhancement is necessary on the Gen 4 models. It’s solid in hand & offers a definite feel even when the palms get sweaty.

Glock 31 Build

For the record, it should be noted that this review is dealing with the Glock 31 Generation 4 – the latest iteration in the G31’s lifespan, & the most updated of the line. Part of the benefit of owning a Gen 4 Glock gun is in the interchangeable backstraps provided by Glock – a feature that makes for a further broadly appealing, easy handgun as far as build & handle. The company grip of the G31 is a bit on the compact size as opposed to prior Glock standards, but whether or not this is optimal would depend on the hand size & preferences of the individual handling the gun. Overall, the build of the Glock 31 supports the equal universal template established by the other members of the Glock family – a polymer & metallic blend in the body, a slide with convenient ribbing at the end for improved grip, ergonomic thumb grooves for the grip,convenient & easy directions especially in the Gen 4 model which utilized a larger magazine release button.

Glock 31 Shooting

What’s the most critical factor when deciding on a gun to purchase? Why performance of course! Thankfully for Glock, the G31 has a well-founded reputation for return under any & all circumstances – only put, this handgun gets the job done. Personally, I find the Glock 31 to handle better regarding grip & recoil than any other .357 caliber handgun – there is a bit of an improvement in difficulty regarding styling, but as is to be expected when dealing with a gun & cartridge that provide more stopping power. The G31 still handles well & fires accurately even with the increase in force when firing, & it holds up remarkably well after hundreds & hundreds of rounds shot. Quite just, this is a gun that shoots accurately, forcefully, & reliably.

Glock 31 with Extended Magazine

The Glock 31 comes furnished with a factory standard, 15-round magazine – impressive, given the performance & power of this .357 caliber gun. As previously stated, the G31 Gen 4 incorporates a new & improved magazine release button, as well as a more reliable, smooth well – loading, clearing, & re-loading the Glock 31 is as comfortable as can be. The Gen 4 version of the Glock 31 also utilizes a reversible magazine well for enhanced ease of use. If 15 rounds aren’t enough, there are in fact a number of extended magazine options available which are manufactured & sold by Glock in addition to various third parties – although this will compromise on the form factor & compact size of the weapon, as many as 17 rounds can realistically be loaded into the G31.

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Glock 31 Sights

The Glock 31 utilizes st&ard polymer sites on the front & back of the slide of the gun, with a single dot on the front & a notched rear section marked & enclosed by a white “U” outline. Frankly, in my personal opinion, these sights are very underwhelming – as a gun buyer who prioritizes home defense, I strongly prefer night sights on my handguns, but the beauty of Glock’s is partly in the number of different sights & accessories available for purchase to suit people’s personal preferences. If the standard G31 sights don’t get the job done for you, make sure you discover sights that do – there are enough options available that this should not be an issue.

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Glock Trigger Safety

It’s always refreshingly obvious that Glock prioritizes safety above all else, & that is of great benefit to all Glock buyers, including Glock 31 owners. As is the case with most of their newer models & in the generation 4 Glock’s, the Glock 31 utilizes Glock’s breakthrough registered Glock ‘Safe Action System’, a three-part safety system designed to eliminate the safety concerns of handguns & ensure the safest, most reliable experience possible.

The first part of the three-part Glock ‘Safe Action System’, the trigger safety, incorporates a level into the trigger which, when in the forward position, blocks the trigger from moving backward. To fire the gun, both the trigger safety & the trigger need to be engaged at the same time – if the security is not depressed, the weapon will not fire. Secondly, there is the firing pin safety, a spring-loaded safety which projects into the firing pin channel & blocks the firing pin from moving forward.

The security is cleared when the trigger is engaged, & the safety automatically re-engages during the slide cycling, meaning the gun is simply going to fire when the user wants it to burn. Lastly, there is the drop safety – reasonably self-explanatory, the drop safety prevents inadvertent firing as a result of dropping the gun, a puzzle that has unfortunately been associated to plague certain handgun manufacturers & models.


Glock 31 with Accessories

The Glock 31 is a Glock gun – what else wants to be said regarding accessorizing, modifying, & customizing it? Being the powerhouse gun business that they are, it should come as no wonder that there are a plenty of options when it comes to tailoring your Glock action to you with accessories. The Glock 31, like almost all Glock guns, can be customized in some ways – try different sights, grips, lights, magazine extensions, holsters, lasers, & more to make the Glock 31 the perfect gun experience for you.

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Final Notes

A Glock is a talented handgun in any caliber, but when you step up to hot loads like .357s, the stamina of the gun appears shining through with impressively manageable recoil, consistent accuracy, feeding, ejection & a maximum capa- the city of 15+1. This is a lot of weapons to pack on your hip, but when the situation calls for a high-power resistive cartridge that will get the job done, the .357 is a proven choice both for authority enforcement & in the private sector. The Glock 31 Gen4 presents an ideal platform for this cartridge due to its lighter overall weight, rugged construction & history of reliability in the field. For more information call 770-432-1202 or visit

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