The Glock 45 MOS remains one of the most practical crossover handguns on the market for law enforcement and serious shooters alike. It was one of America’s favorite handguns before the advent of the Glock 45 Gen 6 and its cousins, and the trend has continued unabated since. There’s actually a pretty good chance that, if you’re reading this, you’ve already tried or even own one.
The Evolution of the Crossover Pistol
Gaston Glock set a new standard for handguns with his brand back in the 1980s, and that continues to dominate today. It took some time for people to realize the new “plastic” pistol was a serious contender. At the time, all-steel guns were the standard, and plastic seemed cheap. Now, some would argue that Glock pistols are the biggest innovation in firearms since Browning’s 1911 handgun.
Unlike 1911 pistols, however, there are not many choices when it comes to style and color. Glock pistols all look the same. So why all the fuss over the Glock 45 MOS pistol, of any generation?
All photos by Jason Mosher unless otherwise indicated.
What is a Glock 45?
The Glock 45 is a 9mm handgun that was designed with law enforcement in mind. For decades, the Glock 17 has been the most popular choice of handgun for law enforcement, while the Glock 19 is the most popular outside of law enforcement. It only makes sense that Glock would blend these two iconic pistols.
Using the G17 grip and G19 slide for a crossover pistol is not a new design. In fact, Glock did this first with the G19X. In their bid to win the US Army Modular Handgun Competition, Glock developed the 19MHS, which was released to the public as the 19X at the NRA Annual Meeting (NRAAM) in Indianapolis in 2019.
The 19X was a popular handgun and Glock has sold more than 100,000 of them to date. But they also saw an opportunity for a handgun they could market to law enforcement as well. And so, the Glock 45 was born. Now, more and more agencies are switching to the Glock 45 because it provides the best of two worlds. At least for some…
I’ll admit, I’m a big fan of the Glock 49, which is the direct opposite of the Glock 45’s full-size G17 frame and G19 slide in an optic-ready platform. But it’s still hard to ignore the benefits of the G45 MOS handgun.
My agency switched because we wanted to upgrade to an MOS pistol, and we thought the Glock 45 had more to offer. The shorter barrel on the G45 gives it great balance and a faster time clearing the holster. Having a shorter barrel/holster is more comfortable sitting in a car as well.
While the barrel is shorter, however, the magazine well is the same as the G17, so you don’t sacrifice ammo capacity.
Glock Model Number Naming Conventions
The G45 is not a .45 caliber handgun even though this is an easy assumption to make. Just like a Glock 22 is not a .22 caliber, and the G40 is not a .40 caliber handgun. If the models confuse you, thank Glock for the intuitive names they give their pistols. Following a simple numerical sequence, Glock names each pistol in order of its patent filing.
Technical Comparison: G45 MOS vs. G19X vs. G49
To understand how the G45 fits into duty work, it helps to see how it compares directly to its closest crossover relatives:
| Feature | Glock 45 MOS | Glock 19X | Glock 49 MOS |
| Frame Size | Full Size (G17 length) | Full Size (G17 length) | Compact (G19 length) |
| Slide Length | Compact (4.02 in) | Compact (4.02 in) | Full Size (4.49 in) |
| Caliber | 9x19mm | 9x19mm | 9x19mm |
| Standard Capacity | 17+1 | 17+1 / 19+1 | 15+1 |
| Slide Finish | Black nDLC | Coyote nPVD | Black nDLC |
| Magwell | Flared | Standard w/ Lanyard Loop | Flared |
| Optic Ready (MOS) | Yes | No (Standard) | Yes |
| Front Serrations | Yes | No | Yes |
Beyond the technical specifications, key aesthetic and functional differences exist between the G45 and G19X. The G19X is produced with an nPVD Coyote slide finish, whereas the G45 uses a black nDLC finish (with factory factory finish options including FDE, BFG, and Grey).
While not immediately noticeable when holding the gun, the G45 frame is approximately 1mm wider than the G19X due to its flared magwell. The G45 also introduced factory front slide serrations to facilitate easier press checks
Why the Glock 45 MOS Excels for Duty Use
As mentioned above, Glock developed the G45 with law enforcement in mind. A longer barrel has some advantages, but the shorter barrel on the G45 compared to the G17 is appealing. Even though I like the G49, I can’t ignore the balance of the G45 when firing.
A longer frame provides more hand support when shooting, while a longer barrel offers slightly higher muzzle velocity. But a shorter barrel makes the gun lighter overall, and it’s significantly easier to carry around all day on a duty belt. I’ve been carrying a duty gun for nearly two decades, and it’s surprising how much difference the shorter barrel makes.
I’m obviously not the only one who thinks so, either. There are numerous reports from LE, military, and similar training sources indicating that many shooters find the G17-length grip and G19-length slide to have an excellent center-of-mass balance. That’s a trait that lends itself to better gun handling for many shooters, particularly when it comes to speeding up transitions between multiple targets.
Duty Advantages: Speed and Capacity
Regardless of the ergonomics of the gun, cops want lots of ammo, and the G45 uses the G17 mags. Standard mags hold 17 rounds and extended mags are available as well.
When it comes to drawing the gun, a shorter barrel also makes a difference. The average time to draw and fire reduces by a fraction of a second on almost every shooter we have timed. A fraction of a second doesn’t sound important, but in a life-or-death incident, it is.
Glock 45 MOS Holster & Optics Compatibility
Because the G45 utilizes a G19-length slide on a G17 frame, holster selection is straightforward—most duty holsters built for the G19 or open-ended G17 platforms fit seamlessly. But if you want a holster made specifically for the Glock 45, Safariland has you covered. The Safariland holster finder makes selecting the right fit simple.
Recommended Duty Holsters
My favorite holster for the G45 is the Safariland 7360 RDS Duty Holster, which has both the SLS (Self Locking System) and ALS (Automatic Locking System) retention systems. It also has a rotating hood that covers your optic when holstered. When selecting a holster, you can configure it for your specific optic and weapon-mounted light.
Safariland offers a wide range of color finishes on their holsters along with different styles. I’ve used Safariland holsters for years for duty and personal use and I haven’t seen anything better.
Navigating the Modular Optic System (MOS)
When it comes to red dots, Glock’s factory-cut MOS system allows you to mount a wide range of optics directly to your slide using interchangeable adapter plates. Instead of paying a gunsmith to custom-mill your slide, you select the plate matching your optic footprint.
Included with the G45 MOS is a set of factory plates matching common mounting footprints. Some of my favorite duty optics for this platform include:
- Aimpoint ACRO P-2 (Enclosed emitter durability)
- Trijicon RMR / HD (Industry standard ruggedness)
- Steiner MPS (Crisp glass and rugged housing)
- Vortex Defender-ST (Versatile window size)
- Holosun 407c / 507c (Reliable performance and solar backup)
If you prefer iron sights, Glock also offers the standard G45 without the MOS cut.
Glock 45 Gen 5 MOS vs. Gen 6: Is the Gen 5 Still Relevant?
The release of the Glock 45 Gen 6 brought several factory updates based on popular aftermarket modifications.
Key additions include an integrated frame palm swell paired with RTF6 texture for enhanced grip control without stippling, alongside a deep trigger undercut and textured thumb rests that improve the control structure for faster follow-up shots. Additionally, it features a factory flat-faced trigger for a cleaner break out of the box and an updated optic mounting system (A-CUT) for more streamlined optic plate integration.
Even with the Gen 6 on the market, the Gen 5 G45 MOS remains a premier choice for agencies and individuals:
- Holster Cross-Compatibility: The external slide and frame dimensions of the Gen 6 match the Gen 5, meaning your existing Safariland duty holsters fit both generations perfectly.
- Proven Track Record: Thousands of law enforcement agencies across the country have deployed and standardized on the Gen 5 G45 MOS.
- Established Armorer Support: Parts, magazines, and aftermarket support for the Gen 5 platform are abundant and universally available.
Glock 45 MOS Specifications Quick Reference
| Specification | Measurement |
| Caliber | 9x19mm |
| Action | Safe Action® |
| Capacity | 17+1 standard (accepts up to 33-round factory mags) |
| Barrel Length | 4.02 inches (Glock Marksman Barrel) |
| Slide Length | 6.85 inches |
| Overall Width | 1.34 inches (34 mm) |
| Weight (Unloaded) | 21.73 oz |
| Trigger Pull | ~26 N (5.8 lbs) |
Frequently Asked Questions
What is the main benefit of the Glock 45 MOS crossover design?
The Glock 45 MOS combines a full-sized Glock 17 frame with a compact Glock 19 slide. This pairing gives shooters a full 17+1 round grip for recoil control while providing a shorter slide length that clears retention duty holsters faster and sits comfortably while seated in patrol vehicles.
Will a Glock 45 MOS fit in standard Glock 17 or Glock 19 holsters?
The Glock 45 MOS fits standard Glock 19 duty holsters and open-ended Glock 17 duty holsters. For weapon light and optic configurations, purpose-built duty holsters like the Safariland 7360RDS ensure precise Level III retention fit.
What is the difference between the Glock 19X and the Glock 45 MOS?
While both are 9mm crossover handguns, the G19X features a Coyote nPVD finish, lanyard loop, and standard slide without optic cuts. The G45 MOS features a black nDLC finish, factory front slide serrations, a flared magwell, no lanyard loop, and Glock’s Modular Optic System (MOS) slide cut.
Are Gen 5 Glock 45 MOS holsters compatible with the Glock 45 Gen 6?
Yes. The external slide dimensions and frame attachment points of the Glock 45 Gen 6 mirror the Gen 5 model. Safariland RDS retention holsters engineered for the G45 MOS Gen 5 accommodate the G45 Gen 6 seamlessly.
Final Thoughts
My personal preference leans toward the G49 for certain setups due to the short-grip/long-barrel configuration. But when it comes to a dedicated duty or self-defense handgun, the G45 MOS is tough to beat.
You get reliability, high capacity, exceptional balance, and maneuverability in one proven package. It is widely used by law enforcement agencies across the country and remains a top-tier choice for home defense and tactical shooting. Whether you choose the battle-tested Gen 5 MOS or the newer Gen 6, the Glock 45 crossover concept has firmly earned its place in modern duty carry.
