Review of the MSBS Grot, the Polish Assault Rifle (Ukrainian Experience)

The MSBS GROT is the newly adopted service rifle of the Polish Armed Forces. It is manufactured by Fabryka Broni “Łucznik” in Radom, a company that is part of the state-owned Polish Armaments Group.

MSBS Grot in the hands of a soldier from the 24th Mechanized Brigade on January 20, 2023.

Ukraine has received approximately 10,000 MSBS Grot assault rifles, specifically the C16A1 and C16A2 variants, from Poland. These rifles were provided as part of military aid rather than through a direct purchase agreement. The Polish government donated these weapons to support Ukraine’s defense efforts following the onset of the Russian invasion in 2022 .

In Ukraine, these carbines immediately went into battle and received highly mixed reviews: some were impressed, while others reported numerous quality issues.

Advantages:

Ergonomics
Easy installation of red dots / optical sights
Comprehensive set of accessories
Reliable performance
Easy cleaning thanks to piston-driven gas system

Disadvantages:

Unreliable operation
Broken bolts
Fractured firing pins
Other malfunctions

In other words, the reviews were completely contradictory, making it necessary to understand the real cause of these issues.

After hearing complaints from our military personnel, I began investigating the issue and discovered that the initial versions (C16-FB-A0), which were delivered to the troops in 2017, had design flaws. Later, the carbines were improved to version C16-FB-A1 and then to C16 FB-M2.

Problems with C16-FB-A0 generation

Photos from Media Drama Over Poland’s MSBS Grot Rifle Causes National Security Concerns in Poland:

The lower receiver of MSBS obliterated by the gun malfunction

A visible crack on the gun lock of the MSBS civilian version. According to the user, he put only 500 rounds through the gun

The Grot rifle imported for the civilian market, which I tested, was manufactured in the fall of 2022 specifically for the Ukrainian market. My experience with this rifle during testing exceeded 300 rounds and 1000 rounds during making of torture test video later. During this period, I did not encounter a single malfunction, even when firing on a hot day with a suppressor. Although this is not enough to fully assess its durability, I can share my impressions of its use and ergonomics.

Modular Design:

The Grot was designed as a modular rifle, which is why it comes with two barrels:

A 16-inch barrel (1:9 twist rate)
A 10.5-inch barrel (1:7 twist rate)

The shorter barrel is equipped with an ASE UTRA SL7 sound moderator. The Grot uses a piston-driven gas system, which simplifies cleaning and reduces part heating.

Compact and Maneuverable:

With the short barrel, the weapon is highly compact and maneuverable. To comply with Ukrainian regulations, the stock is fixed and does not fold to the side, but it does have adjustable length and a cheek rest.

Ergonomic Features:

The rifle comes with a vertical foregrip, which proved to be quite comfortable, especially when the handguard heats up during intensive shooting. The handguard itself features an M-Lok interface for attaching additional accessories.

User-Friendly Controls:

The ambidextrous charging handle, bolt release lever, and safety selector are very convenient, significantly improving the user experience.
Left-handed shooters will find it easy and comfortable to operate.
The direction of ejection can also be changed, although I must admit I did not test this feature.
The bolt release lever is an interesting design and can be easily pressed with the index finger.

When shooting from the left shoulder with the standard ejection direction, there is some gas blowback to the face, though not as severe as with the AR-15.

Sights and Optics:

The rifle comes with factory-installed folding metal sights (front sight and rear sight).
The rear sight features two diopters of different diameters, designed for close and long-range targets.

Balance and Recoil Control:

The balance is slightly front-heavy due to the suppressor, but this helps reduce muzzle rise, positively affecting accuracy.
In my opinion, a silencer is almost essential for barrels of this length because, without one, the sound resembles that of a howitzer, and it produces a massive “fireball.”
The performance of this sound moderator is simply outstanding. If you have ever heard the loudness of a short-barreled shot without a moderator and then compare it to the sound of the Grot with the ASE Utra SL7, you will immediately understand how effectively it reduces the shot’s noise.

Magazine Compatibility and Functionality:

One thing that stood out was how smoothly and securely the magazine attaches to the Grot.
However, it is worth noting that the latest generation of Magpul magazines is not compatible with this rifle.

Heat Management:

With the suppressor attached, the weapon heats up much faster during intensive shooting.
Therefore, I recommend using a high-quality heat-resistant cover for the suppressor.

Overall Impressions:

My overall experience has been very positive, but we will continue testing to personally evaluate the improvements in the new generation.

Feedback from Ukrainian soldier:

Hello everyone,

We have the Grot as standard-issue weaponry in our unit. I remember back in 2022, when we were issued brand-new (well, almost) Grots to replace the old Kalashnikovs. The unit was immediately divided, which was not surprising.

On one hand, we had a smooth trigger pull—especially compared to the AK—ambidextrous controls, a telescopic stock, and fairly comfortable iron sights. On the other hand, it was exactly like in the video Vitaliy watched during disassembly: “Don’t lose anything.” Disassembly and reassembly seemed like a nightmare, especially in field conditions. But as experience has shown, it wasn’t necessary. It can indeed handle a high round count without any problems. Just make sure not to melt the barrel.

Personally, I’m a mortar operator, so I only used the Grot on the shooting range (thank the gods). But the guys in the rifle companies were surprised by its durability. Many feared it would quickly get clogged with dirt, but that didn’t happen.

Of course, there were malfunctions and some incidents, but overall, I would say that the Grot passed the test in Donbas—surviving -20°C temperatures, rain, and mud. You’ve seen how it handles sand yourselves.

One last thing—take care of the “needle” (firing pin)!

Personally, I really liked the carbine, especially with an ACOG.

Around the fourth day at the position, I noticed that the compensator was clogged with dirt. I even had an idea to fire a shot and see what would happen. 😅

And I just remembered another problem (maybe it has been fixed by now): if it starts rusting, that’s it. No matter how much you clean it, the only option is to preserve it with oil.