Glock 31: Complete Guide to the .357 SIG Glock Pistol

The Glock 31 stands as one of Austria's most powerful contributions to law enforcement and personal defense firearms. This full-size pistol chambered in .357 SIG delivers exceptional stopping power with a 15-round magazine capacity, making it ideal for professional and personal protection scenarios. The pistol combines Glock's legendary reliability with the high-velocity performance that .357 SIG ammunition provides.

What sets the Glock 31 apart from other handguns is its ability to deliver rifle-like velocity in a pistol format. The .357 SIG caliber offers superior ballistic performance compared to traditional pistol rounds, with muzzle velocities reaching approximately 1,350 feet per second. This translates to better penetration and stopping power when it matters most.

Law enforcement agencies and civilian shooters who demand maximum performance often choose the Glock 31 for its proven track record. The pistol features Glock's Safe Action trigger system, polymer frame construction, and steel slide with a corrosion-resistant finish. Prices typically range from $500 to $650, making it accessible to serious shooters who need professional-grade performance.

Key Takeaways

• The Glock 31 fires .357 SIG ammunition with exceptional velocity and stopping power for law enforcement and personal defense

• This full-size pistol holds 15 rounds and features Glock's reliable striker-fired action with multiple safety systems

• The pistol offers excellent accuracy and durability while remaining customizable through various accessories and grip modifications

Glock 31 Overview

The Glock 31 is a full-sized pistol chambered in .357 SIG, designed for high-velocity performance and stopping power. This striker-fired handgun serves law enforcement, military, and civilian shooters with its 15-round capacity and proven reliability.

What Is the Glock 31?

The G31 is a semi-automatic, striker-fired pistol that fires the .357 SIG cartridge. The Glock 31 measures 8.03 inches in total length with a 4.49-inch barrel.

The pistol features a polymer frame construction that reduces weight while maintaining durability. Its design incorporates Glock's Safe Action trigger system with three internal safeties.

Key Specifications:

• Caliber: .357 SIG

• Barrel Length: 4.49 inches

• Overall Length: 8.03 inches

• Magazine Capacity: 15 rounds

• Frame Material: Polymer

The .357 sig pistol uses polygonal rifling in its barrel, which reduces fouling and increases muzzle velocity. This rifling pattern contributes to the pistol's accuracy and barrel longevity.

The Glock 31 pistol includes fixed sights with a white dot front sight for low-light visibility. An integrated accessory rail allows mounting of tactical lights and lasers.

Purpose and Applications

Law enforcement agencies adopted the Glock pistol for duty use due to its high-velocity rounds and reliable performance. The .357 SIG cartridge delivers flat trajectory and excellent stopping power for defensive applications.

Military personnel use this Glock pistol in situations requiring precision at extended distances. The high muzzle velocity makes it ideal for long shooting distances.

Civilian shooters choose the G31 for:

• Self-defense: High stopping power and reliability

• Target shooting: Accurate performance at various distances

• Competition: Consistent trigger pull and quick reset

The pistol's ergonomic grip design ensures secure handling during rapid fire. Aggressive texturing on the frame provides control in adverse conditions.

Professional users value the 357 sig pistol for its ability to penetrate barriers while maintaining accuracy. The cartridge's design bridges the gap between traditional handgun rounds and magnum performance.

Gen 3 vs Gen 4 Models

The Gen 4 Glock 31 includes interchangeable backstrap panels for different hand sizes. This system allows shooters to customize the grip circumference for optimal fit.

Generation 3 Features:

• Fixed grip size

• Standard magazine release

• Single recoil spring assembly

Generation 4 Improvements:

• Multiple backstrap options (small, medium, large)

• Enlarged, reversible magazine catch

• Dual recoil spring assembly

• Improved trigger mechanism

The Gen 4 version provides better handling and versatility compared to earlier models. The dual recoil spring system reduces felt recoil and improves control.

Both generations maintain the same external dimensions and holster compatibility. The newer generation offers enhanced ergonomics without changing the proven Glock pistols reliability.

Magazine compatibility remains consistent between generations. Shooters can use Gen 3 magazines in Gen 4 pistols and vice versa.

Specifications and Key Features

The Glock 31 pistol delivers high muzzle velocity through its .357 SIG chambering and offers a large magazine capacity of 15 rounds in a full-size polymer frame. This pistol combines precise engineering with Glock's reliable Safe Action System for consistent performance.

Caliber and Chambering

The Glock 31 is chambered in .357 SIG, a high-performance cartridge developed in 1994 for law enforcement use. This cartridge uses a .40 S&W case necked down to accept 9mm bullets.

The .357 SIG typically fires 124-125 grain bullets at velocities reaching 1,390 feet per second. This high muzzle velocity makes it ideal for long shooting distances and provides excellent penetration capabilities.

Despite its name, the .357 SIG uses 0.355-inch diameter bullets, the same as 9mm ammunition. The cartridge delivers more power than standard 9mm while maintaining manageable recoil in the Glock platform.

Barrel and Overall Dimensions

The Glock 31 features a 4.49-inch barrel length that contributes to its accuracy and velocity performance. The overall length measures 8.03 inches with the standard grip configuration.

The Gen4 model offers three backstrap options that adjust the overall length:

• Standard: 7.95 inches

• Medium: 8.03 inches

• Large: 8.11 inches

The trigger reach also changes with each backstrap, ranging from 2.76 to 2.91 inches. This allows users to customize the fit for different hand sizes.

The pistol maintains the full-size Glock frame dimensions while accommodating the powerful .357 SIG cartridge.

Magazine Capacity and Weight

The Glock 31 holds 15 rounds in its standard magazine, providing substantial firepower for duty or defensive use. Additional magazine options include 10-round and 16-round capacities.

The pistol weighs 23.28 ounces empty and approximately 33.5 ounces when fully loaded with 15 rounds. The polymer frame construction keeps weight down while maintaining durability.

This weight distribution provides excellent balance despite the lightweight frame. The substantial loaded capacity makes it suitable for extended engagements while remaining manageable for carry.

Safe Action System

The Glock 31 uses Glock's Safe Action System instead of a traditional manual safety. This system incorporates three independent safety mechanisms that work automatically.

The factory trigger pull measures 5.5 pounds with a short reset for rapid follow-up shots. The trigger includes a safety tab that must be depressed for firing.

The Gen4 model features a dual recoil spring system that helps manage the .357 SIG's substantial recoil. This design reduces muzzle flip and improves control during rapid firing.

The system requires no manual safety engagement or disengagement, allowing for immediate deployment when needed.

Performance and Ballistics

The Glock 31 delivers impressive ballistic performance with its .357 SIG chambering, combining high velocity with manageable recoil characteristics. The pistol demonstrates excellent accuracy capabilities and produces significant muzzle velocities that exceed many conventional handgun cartridges.

Recoil and Handling

The Glock 31's recoil management system effectively controls the .357 SIG's substantial energy output. The Gen4 model employs a dual recoil spring system that helps mitigate muzzle flip and reduces felt recoil.

Despite the .357 SIG's power, the pistol remains surprisingly manageable. The recoil feels similar to a 9mm +P cartridge rather than what shooters might expect from a .357 caliber round.

The Gen4 version includes interchangeable backstrap panels that allow users to customize grip size. This feature helps optimize recoil control for different hand sizes.

Key Recoil Features:

• Dual recoil spring system

• Adjustable grip backstraps

• Polymer frame absorbs energy

• Balanced 33.5-ounce loaded weight

Accuracy and Range

The Glock 31 produces consistent accuracy results across various ammunition types. Test results show five-round groups measuring 1.25 inches at 50 feet using quality hollow point ammunition.

The .357 SIG cartridge's flat trajectory enhances accuracy at longer distances. This characteristic makes the pistol suitable for precision shooting beyond typical handgun ranges.

The Glock 31 demonstrated superior reliability compared to other .357 SIG pistols in testing. It functioned flawlessly with all ammunition types tested.

Fixed tritium sights provide excellent visibility in various lighting conditions. Optional steel sights and adjustable rear sights are available for enhanced precision.

Muzzle Velocity

The Glock 31 generates impressive muzzle velocities that significantly exceed standard handgun cartridges. Testing with 125-grain ammunition produced velocities averaging 1,390 fps through the 4.49-inch barrel.

The high muzzle velocity makes the Glock 31 ideal for long shooting distances. The .357 SIG cartridge maintains energy better than 9mm or .40 S&W at extended ranges.

The cartridge uses a necked-down .40 S&W case with 9mm bullets. This design creates additional powder capacity for higher velocities than traditional straight-walled cases.

Velocity Comparison:

• .357 SIG: 1,390 fps

• 9mm: ~1,150 fps

• .40 S&W: ~1,050 fps

The high velocity contributes to excellent penetration characteristics for defensive applications.

Comparisons with Other Glock Models

The Glock 31 stands out among Glock pistols for its .357 SIG chambering, offering different performance characteristics than popular models like the Glock 19 and Glock 22. It also provides distinct advantages over traditional .357 Magnum revolvers in capacity and reload speed.

Glock 31 vs Glock 19

The Glock 19 chambered in 9mm represents one of the most popular compact pistols, while the Glock 31 serves as a full-size option in .357 SIG. The size difference creates distinct advantages for each model.

Size and Capacity Differences:

• Glock 19: Compact frame, 15-round capacity

• Glock 31: Full-size frame, 15-round standard capacity

The Glock 19 offers better concealment due to its shorter grip and barrel length. Its 9mm ammunition costs less and produces lighter recoil, making it easier for new shooters to control.

The Glock 31 delivers superior velocity and energy compared to the 9mm cartridge. The .357 SIG round travels faster and hits harder than 9mm, providing better stopping power for defensive situations.

Recoil management differs significantly between these models. The Glock 19's 9mm produces mild recoil that most shooters handle easily. The Glock 31's .357 SIG creates sharper recoil but remains manageable due to the full-size frame's weight.

Glock 31 vs Glock 22

Both pistols share the same full-size frame dimensions, making this comparison focus primarily on cartridge performance. The Glock 22 chambers .40 S&W while the Glock 31 uses .357 SIG.

Ballistic Performance:

The .357 SIG cartridge provides superior velocity and energy compared to .40 S&W ammunition. This translates to flatter trajectory and better terminal performance at longer distances.

Ammunition costs favor the Glock 22, as .40 S&W rounds cost less than .357 SIG cartridges. The .40 S&W also offers wider availability in most gun stores and ranges.

Both pistols use the same magazine capacity and share identical ergonomics. Shooters familiar with one model can easily transition to the other without learning new controls or grip techniques.

Glock 31 vs .357 Magnum Revolvers

Traditional .357 Magnum revolvers offer powerful performance but differ significantly from the Glock 31 in design and operation. The comparison reveals modern semi-automatic advantages versus classic revolver reliability.

Capacity and Reload Speed:

• Glock 31: 15+1 rounds, fast magazine changes

• .357 Magnum Revolver: 6 rounds, slower cylinder reload

The Glock 31 provides more than double the ammunition capacity of most .357 Magnum revolvers. Magazine changes take seconds compared to the longer process of reloading individual cartridges or using speed loaders.

Ballistic performance varies between these platforms. .357 Magnum revolvers can fire both .357 Magnum and .38 Special cartridges, offering versatility in power levels. The .357 SIG cartridge in the Glock 31 delivers similar energy to .357 Magnum loads but in a semi-automatic platform.

Weight differences affect carrying comfort. Most .357 Magnum revolvers weigh more than the lightweight polymer-framed Glock 31. The Glock's synthetic construction reduces carry weight while maintaining durability.

Maintenance requirements favor the Glock 31's simpler design. Revolvers require more detailed cleaning of the cylinder and forcing cone areas, while the Glock's fewer moving parts simplify field stripping and cleaning procedures.

Customization and Accessories

The Glock 31 accepts most standard Glock accessories and modifications designed for full-size models. Popular upgrades include enhanced sights for better target acquisition, extended magazines for increased capacity, and compatible holsters for various carry methods.

Night Sights and Sight Options

The standard Glock 31 comes with basic polymer sights that work but leave room for improvement. Most shooters upgrade to night sights or fiber optic options for better visibility.

Night sights use tritium inserts that glow in low light conditions. They help shooters acquire targets in dark environments without batteries or external light sources.

Popular sight upgrades include:

• Trijicon night sights with tritium inserts

• TruGlo TFX fiber optic sights

• Ameriglo tritium options

• Dawson Precision fiber optic sights

Fiber optic sights gather ambient light and focus it into bright dots. They work well in daylight shooting but offer no advantage in darkness.

Many Glock pistol owners also add red dot optics. The slide requires milling to accept most red dot mounts. This modification allows faster target acquisition but changes the gun's profile.

Magazine and Grip Upgrades

Standard Glock 31 magazines hold 15 rounds of .357 SIG ammunition. Extended magazines can increase capacity to 22 rounds or more for those who want additional firepower.

Magazine extensions add 2-6 rounds depending on the model. Popular brands include Pearce Grips, Taran Tactical, and Shield Arms. These extensions also provide extra grip surface for better control.

Grip improvement options:

• Talon Grips adhesive texturing

• Stippling (permanent texture modification)

• Grip sleeves for added thickness

• Finger groove removal

The large magazine capacity makes grip control important during rapid fire. Talon Grips offer rubber or sandpaper textures that improve handling without permanent modification.

Extended magazine releases help shooters with larger hands reach the control without shifting grip. The part costs around $15 and installs easily.

Frequently Asked Questions

The Glock 31 raises specific questions about generational improvements, ammunition compatibility, and model differences. Users often ask about its suitability for different applications and how the .357 SIG caliber impacts performance.

What are the improvements in the Glock 31 Gen 5 compared to the Gen 4?

The Glock 31 Gen4 features a double recoil spring system to reduce muzzle flip and improve stability. Gen 4 models include interchangeable backstraps for better grip customization.

The Gen 4 version also offers reversible magazine releases for ambidextrous operation. Some Gen 4 models include the ported barrel option (31C) for enhanced accuracy.

Gen 5 models typically include improved triggers and barrel rifling. However, specific Gen 5 improvements for the Glock 31 vary by production year and regional availability.

What types of ammunition can be used with the Glock 31?

The Glock 31 is chambered specifically for .357 SIG cartridges. This high-velocity round delivers excellent stopping power and flat trajectory performance.

Standard .357 SIG ammunition from major manufacturers works reliably in the Glock 31. The cartridge produces higher velocity than traditional 9mm or .40 S&W rounds.

Users should avoid using any ammunition other than .357 SIG in this pistol. Proper ammunition selection ensures safe operation and optimal performance.

What is the difference in specifications between the Glock 31 and Glock 32 models?

The main difference between Glock 31 and Glock 32 lies in size and capacity. The Glock 31 is a full-size pistol with a longer barrel for greater accuracy.

The Glock 31 holds 15 rounds in its standard magazine. The Glock 32 is compact with 13-round capacity, making it better for concealed carry.

Both models use the same .357 SIG cartridge. The Glock 31 offers better accuracy at longer distances due to its 4.49-inch barrel length.

Is the Glock 31 suitable for both personal defense and law enforcement use?

The Glock 31 is utilized by law enforcement, military personnel, and civilian shooters. Its reliability and stopping power make it effective for duty use.

The .357 SIG cartridge provides excellent performance for self-defense applications. The full-size frame offers good control and accuracy for both professional and personal use.

Law enforcement agencies appreciate the consistent trigger pull and easy maintenance. Civilian users benefit from the same reliability and performance characteristics.

How does the caliber of the Glock 31 affect its performance and handling?

The .357 SIG cartridge produces higher velocity and energy than 9mm or .40 S&W rounds. This results in flatter trajectory and better penetration for defensive situations.

The powerful cartridge creates more felt recoil than smaller calibers. However, the Glock 31's design helps manage recoil through its polymer frame and ergonomic grip.

Shooters experience slightly more muzzle flip with .357 SIG ammunition. The pistol's low bore axis and balanced design help maintain quick follow-up shot capability.

Can the Glock 31 be easily modified or upgraded with aftermarket parts?

The Glock 31 can typically be converted to fire .40 S&W with a simple barrel swap and magazine change. This allows users to switch between calibers easily.

Standard Glock aftermarket parts fit the Glock 31 frame. Triggers, sights, and internal components have wide availability from multiple manufacturers.

The integrated accessory rail allows attachment of lights and lasers. Users can customize grips, magazine extensions, and other external components without difficulty.