GLOCK is one of the most renowned pistol brands in the world, used by military units, police forces, and countless firearm enthusiasts. Its design is simple and austere (very "Austrian") but boasts proven effectiveness.

The airsoft replica license for GLOCK is exclusively held by Umarex, which now brings us the highly anticipated MOS range within their pistol lineup—a dream come true for fans of this iconic brand.

MOS System

(Modular Optic System)

The "MOS" in the name of this model refers to the Modular Optic System, designed to allow the installation of integrated optical sights on the pistol's slide. This system features a cut-out on the slide, accessible by removing the two top screws. Over this space, one of four included mounting plates can be installed. These plates serve as bases to ensure the red dot sight is properly seated on the slide’s structure.

Mounting Plates

The plates are numbered 01, 02, 03, and 04 and are designed to accommodate red dot systems from brands like:

• Docter

• Trijicon RMR

• Leupold DeltaPoint

• C-More STS

For airsoft use, you’ll need replicas of these optics. To illustrate the cost difference, an original Trijicon RMR retails for around €800 in Europe, whereas the RMR for airsoft is around 30 euros.

Fit and Compatibility

During our tests with the RMR plate and five different red dot sights (all Trijicon replicas), we couldn't achieve a perfect fit. The issue lies in the plate’s lugs, which are slightly thicker and do not align correctly with the base of the RMR.

This could be due to the quality of the RMR replicas we tested. Nevertheless, the RMR-style red dot sight remains securely mounted and performs its function adequately.

Performance and Power

This model is compatible with both gas magazines (usable with previous G17 models and variants) and CO2 magazines using 12-gram cartridges.

CO2 provides more stable pressure compared to gas and is less affected by ambient temperature, which is a significant advantage during winter. This is particularly important because each CO2-powered shot must move multiple components: the metal slide, the red dot mounting plate, the red dot sight itself, and often heavier BBs.

The CO2 magazine autonomy is approximately 40 shots (equivalent to two full magazines), though this may vary depending on the shooting cadence and temperature.

Who is Behind the MOS Model?

The new GLOCK 17 GEN5 MOS may be manufactured by Star Rainbow (SRC), a Taiwanese company seemingly replacing VFC for this model’s production. While Umarex hasn’t officially confirmed this, it seems plausible.

Does This Change Anything?

The external quality remains on par with previous models, using the same polymers and metal slide. The main difference lies in the hop-up system, which reverts to a more traditional design.

Additionally, gas magazines from older models, such as the GLOCK 17 and GLOCK 17X, are fully compatible with this MOS version.