Test: Glock G21 Gen5 MOS, a full size polymer pistol in .45 ACP

The .45 ACP (aka .45 Auto) still has its supporters, even though ammo prices can already put a significant dent in the wallet. In the huge U.S. market, this Glock model could well find its buyers. With the 5th generation, it has been technically and ergonomically updated and can now also be equipped with red dot sights mounted on the slide. Reason enough to take a closer look at the new 5th-generation G21.

Glock recap: these are the features of the Gen5 at a glance

The typical features of this latest generation from Glock are:

  • Glock Marksman Barrel (GMB) with increased accuracy
  • Interchangeable backstraps for improved hand position
  • Double-sided bolt catch lever and the funneled magazine well
  • Front slide cocking serrations

Even at first glance of the new Glock G21 Gen5, it quickly becomes apparent that the slide of the G21 Gen5 model is about 2.5 mm wider than a 9mm G17 slide. Incidentally, this also applies to the models in 10mm Auto caliber, such as the G20. A look at the scales also shows a weight difference of about 100 grams compared to the G47 slide. It is understandable that this pistol turns out to be slightly larger than models in 9mm Luger/.40 S&W: this is an aspect you need to consider if you want to opt for a more powerful caliber. This also applies to the reduced magazine capacity, which is two cartridges less in .45 ACP. The Glock 21 Gen5 MOS costs 970 euros (MSRP).

Ready for the shooting range: rhe Glock G21 Gen5 MOS with a Trijicon RMR.

The Glock 21 Gen 5 MOS on the shooting range

During our shooting performance review, intensive use was made of MOS interfaces. The G21 was equipped with the Trijicon RMR in no time and thus also used on the shooting range. This equipment made the extended visit to the range far more comfortable for the eyes and concentration and resulted in tight groupings.

We tested the G21 in a seated position using a Caldwell shooting rest with five rounds of each ammunition type at 25 meters. A motley mix of training and defensive cartridges with ball, truncated cone or the less feed-friendly semi-wadcutter bullet types between 185 and 230 grains were used to test accuracy and reliability.

It was a surprise when we achieved the smallest 5-shot groups several times. The differences between the S&B 230-grain JHP, the H&N handload with 200-grain KSHP, and the WM factory cartridge with 200-grain SWC bullet were minimal. However, with the typical service pistol hard triggers, such groupings require a decent rest and solid grip technique. The numerous small groups resulted in the average diameter of 39 mm.

The G21 showed itself to be slightly slower to fire and also to recoil, if the powerful Hornady 220-grain Critical Duty test load is disregarded. This has rightly earned the .45 ACP a reputation as a good-natured large caliber.

Large vs. small: handling is quite similar, but dimensions differ between the .45 ACP/ 10mm Auto models and those in smaller calibers.

Handling: the .45 version in comparison with a Glock in 9mm Luger

In terms of handling and shooting feel, the G21 differed only slightly from the classic G17. Therefore, we could not determine any significant differences. The G21 impressed with its accuracy and reliability, which makes it an excellent choice for training.

In conclusion, the G21 convinced us not only in terms of its shooting performance, but also in terms of its handling and shooting feel. It is a reliable pistol for training and offers outstanding accuracy, which makes it an ideal choice for any shooter.

Glock 21 Gen5 MOS spec and price

Model:GLOCK 21 Gen5 MOS
Caliber:.45 ACP 
Magazine Capacity:13 rounds
Frame Grip:Polymer with steel inserts
Slide:Steel, black nDLC coated
Barrel Length, Profile: 117 mm, Glock Marksman Barrel
Rear Sight:4,3 mm, with white, non luminescent outline
Front Sight: 
3.7 mm with white, non-photoluminescent dot
Sight Radius: 
179 mm
Trigger safety, automatic drop firing pin safety
Trigger System, Pull Weight: 
Safe Action, 2,680 g average
Weight (incl. Magazine): 
781 g
Dimensions (LxWxH): 
202x35x140 mm
Hard case with one spare magazine, 2x backstraps, loading aid, cleaning kit
Price (RRP in Germany): 
970 euro
The MOS offers many options. Here, the Glock 21 Gen5 MOS with a Sightmark Mini Shot M-Spec M2 Solar. (Ammo in picture: GECO 230-gr FMJ in .45 ACP, aka .45 Auto.)

Test conclusion: how the Glock G21

in .45 ACP performs

The Glock G21, originally available in .45 ACP, has now been successfully upgraded to the latest Gen5 MOS model. This upgrade means that the G21 can now be equipped with mini-red dot sights, thus meeting the Glock standard for 2023. It is good to see the G21 now included in this series, the most up-to-date one, alongside the G20, which is available in the powerful 10mm Auto caliber.

In the development of the Glock series, we are closely following the numerical order. What can it be expected with the Glock 49 model? The G48 Slimline model already exists. As soon as there is further information on this subject, we will of course inform you.

Test: Tino Schmidt (caliber)

For more information on the G21 and all other Glock please visit the Glock website.

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