Umarex Glock 17 Gen 5 MOS CO2 Full Blowback 4.5mm BB Pistol Table Top Review
First Look & Overview In this table top review, we are taking a look at the Umarex Glock 17 Gen 5 MOS Full Blowback CO2 4.5mm BB Pistol. We will be focusing purely on the table-top aspects for this video, so there is no active shooting featured here; a dedicated field test shooting video will be coming down the road. As a fully licensed replica from Umarex, it offers all the authentic Gen 5 styling and markings you would expect. Today, we are specifically looking at the full blowback version, which prioritizes a true-to-life shooting experience and heavy recoil simulation over pure power and efficiency.
Specifications
Caliber: 4.5mm steel BBs
Action: Single action, full blowback
Magazine: 17-round drop-out magazine
Power Source: 12-gram CO2
FPS: Maximum 300 FPS
Weight: 1.5 lbs (680 grams)
Length: 7.95 inches (20.2 cm)
Barrel: 4-inch (10 cm) smooth bore
Build Quality & Design The Umarex Glock 17 Gen 5 MOS features an incredibly realistic design, boasting a heavy metal slide paired with a durable polymer frame. It completely matches the heft of its real steel counterpart, weighing in at a solid 1.5 pounds, and feels very comfortable in the hand. The slide comes with the signature Gen 5 front serrations and cycle.s completely back during operation, opening the ejection port fully to reveal the wide open magwell
Magazine & Loading System Loading the Umarex Glock 17 Gen 5 MOS BB Pistol is straightforward. It utilizes a heavy, full-size drop-out magazine that holds 17 rounds of 4.5mm steel BBs. The magazine follower can be pulled down and easily locked in place with a quick flick, making loading incredibly fast. Unlike partial blowback models where the magazine pulls forward to seal the breech, this model utilizes a traditional Airsoft-style follower-fed system where the slide simply strips the BB and loads it directly into the breech. While this design is less CO2 efficient and results in slightly less power, it is essential for delivering that complete, highly realistic full blowback action.
Handling & Controls True to the Glock platform, the handling on this replica is extremely authentic. It incorporates an ambidextrous slide catch release that smoothly locks the heavy slide rearward when the magazine runs empty. The single-action trigger pull is relatively light and short. In terms of safeties, it has the classic built-in trigger safety, but Umarex has also integrated an additional cross-bolt safety directly onto the trigger. While it functions well, it can be slightly awkward to push flush and disengage with your finger when you are preparing to shoot.
Sights & Optics This specific MOS (Modular Optic System) version truly shines when it comes to aiming options. Out of the box, it comes equipped with the standard fixed white-dot front and rear sights for easy target acquisition. However, the package also includes an Allen key and four different adapter plates, allowing you to seamlessly mount a variety of micro red dot sights directly to the slide. If you want to add more accessories, the built-in lower rail easily accommodates tactical lights or lasers.
Performance Expectations The Umarex Glock 17 Gen 5 MOS Full Blowback CO2 4.5mm BB Pistol operates with a heavy focus on realism. Because the heavy metal slide travels all the way back with every shot, you get a very satisfying simulated recoil. However, this heavy action demands a significant amount of CO2. As a result, you can expect a slightly lower velocity, coming in at around 300 FPS, and fewer overall shots per CO2 cartridge compared to partial blowback models.
Pros
Realistic Replica in looks, weight, and full blowback function.
Good weight and feel to it, build quality seems excellent as with all the Umarex Licensed Glocks.
Really nice looking and full featured replica of the original Glock 17 Gen 5 MOS.
Fully Glock licensed via Umarex.
Easy to see white dot sights front and back.
Recessed barrel for added realism.
Accessory rail under barrel for adding a laser or tactical light.
Full slide travel blowback action provides a true, hard-recoil shooting experience.
Can be field stripped just like the real steel version.
Cross Bolt Safety built into the trigger.
Full size drop out metal magazine that holds the CO2 and 4.5mm steel BBs.
Slide spring is super snappy and firm, giving an exceptionally crisp and authentic recoil effect.
Warning instructions are nice and discreet under trigger guard.
Lighter, true single-action trigger pull as the full blowback slide cocks the internal striker on every cycle.
Cons
Full blowback action decreases CO2 efficiency, resulting in fewer shots per cartridge.
Slightly lower velocity (300 FPS) due to the heavy slide action.
No adjustable sights out of the box without mounting a red dot.
Final Thoughts The Umarex Glock 17 Gen 5 MOS is a fantastic option for anyone who values maximum realism and training utility over raw FPS. While you do trade some CO2 efficiency for the heavy slide travel, the simulated recoil and authentic handling make it an incredibly enjoyable Airgun to shoot. The inclusion of the MOS plates is a massive bonus for modern shooters wanting to run optics. Stay tuned for the upcoming shooting video to see exactly how this performs down range.

