TFB Review: Glock 45 MOS Reporting For Duty?

Doug E
by Doug E
Police using Glock 45 MOS

Since the original Glock 17 was produced in 1982, there has been about nine different configurations of barrel lengths and grip sizes, but today, we’ll take a look at the curious “crossover” Glock 45 MOS. For those new to Glock pistols, the G45 is chambered in 9mm and features a full-size grip that accommodates the standard 17-round magazine, yet has a compact (4.02 inches) barrel. The “MOS” stands for Modular Optic System and MOS pistols come ready from the factory for a red dot sight of your choosing. Last year, I heard of police departments near me that had decided to issue the Glock 45 MOS as their standard-issue pistol, which made me pause to think “Why?”.

Glock @ TFB:

Glock 45 MOS with TLR-1

GLOCK 45 MOS for law enforcement?

By the time I started my career in law enforcement, Glock was just starting to phase out most of the double action/single action (DA/SA) police pistols in my state. Most of the time that meant that agencies were going with the full-sized models 17 or 22, with an occasional agency issuing the compact size models 19 or 23. The Glock 19X was the first model to combine the full-sized grip, with a compact-sized barrel, when they entered it into the Modular Handgun System (MHS) military trials. At that time, I questioned this configuration, however, in my opinion, it was the optics-ready MOS feature that makes the Glock 45 shine.

When a pistol red dot sight is paired with any pistol, it allows the shooter to focus on the target, rather than on the iron sights. Merely superimposing the red dot onto the object or bad guy you’re focusing on means you’re only using one focal plane, rather than three when aligning a rear sight, front sight, and the target, with the front sight being the primary focal point. Mounting a red dot sight (RDS) to the pistol reduces the need for any iron sights (although I still like having them in case of an RDS failure). Because the RDS is the primary sighting system, which is entirely housed at the rear of the pistol, there’s no need for a longer sight radius. The tradeoff is a slight loss of bullet velocity, between roughly 20-50 fps less compared to a full-size 4.5-inch barrel.

shooting pistols with red dots

In part, another potential plus is that the shorter barrel could slightly reduce the amount of time needed to clear the muzzle from a holster. However, most training I’ve seen regarding pistol red dot optics has the shooter bring the pistol up closer to the eye first, rather than swinging up and out directly from the holster.

Glock 45 MOS Review


Out of the box, the fit and finish of the Glock 45 MOS was perfect as expected, and it fit nicely in my hand. Between all of the Glock models available, I’ve always preferred the small frame full-size grip without any extra grip panels, however, two backstraps came supplied in the case. Glock also includes three 17-round magazines. At the time of this writing, Glock has been machining the Glock 45 MOS slides for several popular optics footprints that allow for direct mounting to the slide, for law enforcement agencies only. For the general market, they are shipping with Glock’s four factory plates, screws, and hex key.

The compact-size Glock 19 pistol seems to receive the most love among all of Glock’s offerings over the years, however, I’ve always preferred the grip of the Glock 17. Thankfully, since the Glock 45 features that 17-sized grip, my hands felt right at home.

full size grip with compact size barrel

Viridian Optics was kind enough to send me their new RFX-35 to pair with the G45 MOS, which features a large, round window and a bright green dot, as opposed to the standard red dot. As previously mentioned the advantage a red (or green) dot presents over iron sights is substantial, so I was thankful for the opportunity to test this combination out. This test and evaluation pistol came equipped with Glock’s suppressor height sights, which are all-metal, finished in black, and the front sight is serrated. Naturally, most of my range time was spent using the green dot sight, but the irons were visible in the bottom of the sight’s window, and the iron sights were dead-on from the factory.

The Glock 45 MOS is configured within the Gen 5 series’ specs that feature an improved trigger pull, and improved rifling in the barrel. I consider myself a capable gunslinger, however, I can’t boast of being able to quantify how much the accuracy is improved with the marksman-style rifling. Although, I was able to hit my MK Machining Covid target at 80 yards consistently. The Glock 45 MOS and Viridian RFX-35 performed flawlessly during my time with them. I’ll save the finer details of the Viridian for its own review soon, but I’ll say that its zeroing and brightness controls are simple to use and the green dot is easily picked up, even on a bright sunny day. I didn’t have any issues with the battery life during the six months in my possession, and I never turned it off during that time.

Results of 80-yard hits on target with the G45 and Viridian RFX35.
Hornady Critical Duty

During my time with the Glock 45, I used Federal American Eagle ammo in 115, 124, and 147 grain, all of which the pistol digested and asked for more. I also switched it up with a bit of defensive ammo, Hornady’s Critical Duty 124 grain +P Flexlock, and Hornady American Gunner 124 grain +P XTP’s, which, unsurprisingly didn’t cause any hiccups either.

Glock 45 MOS Review


Despite the unconventional layout of the crossover Glock 45, upgrading it with a red or green dot sight exploits the advantages of having a shorter barrel, shorter sight radius, and slightly less steel, for a minimal loss of bullet velocity, and no loss of ammunition capacity. Whether you’re looking for a new duty pistol for law enforcement, security, home defense, or just for fun, I recommend considering the Glock 45 MOS. You can find the full specifications and more information on the dedicated G45 MOS page, or visit to view their whole pistol lineup. The Glock 45 MOS has a baseline MSRP of $620 and will vary based on iron sights.

Check Prices on Glock 45 MOS Pistols

If you’re interested in the Viridian RFX 35 green dot, stay tuned for my full review of that coming up soon, but in the meantime, you can visit for more information.

What do you think about the Glock 45 MOS? Are there any other advantages or disadvantages I missed? If you already own one or have shot one, how was your experience? What optic did you mount?

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Doug E
Doug E

Doug has been a firearms enthusiast since age 16 after getting to shoot with a friend. Since then he's taken many others out to the range for their first time. He is a husband, father, grandfather, police officer, outdoorsman, artist and a student of history. Doug has been a TFB reader from the start and is happy to be a contributor of content. Doug can be reached at battleshipgrey61 AT, or battleshipgrey61 on Instagram.

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2 of 17 comments
  • Xerxes036 Xerxes036 on Aug 13, 2023

    "Glock has been machining the Glock 45 MOS slides for several popular optics footprints that allow for direct mounting to the slide, for law enforcement agencies only."

    Glock the MOS is one of the worst handgun optic mounting systems out in the market today offer direct mounting options for the commercial market instead of just LE.

  • Xerxes036 Xerxes036 on Aug 13, 2023

    Im amazed the writer glossed over a plus with using a full sized capacity gun with a shorter slide/barrel hanging on a duty belt while sitting in a police cruiser it helps me keep my hips aligned when in sitting in the driver seat. I personally carry a SIG M18 on duty the difference between sitting in a patrol vehicle with an M9 and an M18 is night and day.