FB MSBS Grot

The MSBS program was in development since 2007 by the Military University of Technology (WAT) in Warsaw with cooperation from the firearms manufacturer Fabryka Broni Radom,^[5][6] and was designed to replace the FB Beryl as the standard-issue service rifle of the Polish Armed Forces.

During initial tests conducted by the Military University of Technology, the MSBS-5.56 and its counterpart Heckler & Koch HK416 were subjected to comparative testing of the barrel and hand-guard for overheating during an intensive firing schedule. According to the tests, MSBS yielded the better results of the two rifles despite having a relatively light and longer barrel profile.^[7] Additional tests have also shown that MSBS is less susceptible to jamming when using lower quality ammunition or when it is insufficiently maintained,^[8] and had a more manageable recoil when fired in fully automatic compared to other assault rifles chambered in the 5.56 cartridge, such as FB Beryl, HK416, FN SCAR-L or CZ BREN 2.^[9]

One of the main design characteristics of the MSBS-5.56 is the modular weapon system. If necessary, a soldier can sacrifice, for example, one standard assault rifle to quickly repair a light machine gun during a firefight. Another feature of the MSBS Grot is barrel changeability, as found on the Steyr AUG. This means a soldier may be able to adapt their rifle based on the environment they are in, such as converting a carbine to a designated marksman rifle, in order to engage targets at a greater range. The benefits of this feature allow an infantry squad to have fewer specialised weapons. MSBS may also be used with components other than the ones manufactured domestically, and it is the first Polish rifle fully compliant with the NATO standards. The MSBS-5.56 features fully ambidextrous controls and Picatinny rail, and it may also be fed from standard STANAG magazines.^[10]

Currently, the MSBS Grot is in service with the Polish Territorial Defence Forces and is scheduled to replace the FB Beryl as the primary infantry weapon and service rifle of the Polish Armed Forces.^[11] Following the adoption of the MSBS-5.56 by the Polish military, the Grot moniker has been added to the MSBS name in honour of the Home Army commander, General Stefan "Grot" Rowecki.^[11][12] The literal translation of the Polish word Grot is “arrowhead” or “spearhead”.

During the 2022 Russian invasion of Ukraine 10,000 Grot C16A2s were sent to the Ukrainian military.^[1][13][14]

On May 9, 2022, the public was informed about the conclusion of an agreement between the Polish Armaments Group and an undefined East African country for the supply of an unspecified number of MSBS Grot assault rifles chambered for 7.62×39mm rounds as specified by the customer, along with 40 mm grenade launchers and optical sights DCM-1 Szafir^[15] manufactured by PCO S.A.^[16]

In January 2025, a photo appeared on the X website (formerly Twitter) showing small arms captured by soldiers of the Democratic Republic of the Congo from M23 rebels, amongst them is an MSBS Grot C chambered in 7.62×39mm cartridge.^[17]

The MSBS Grot is a selective fire modular assault rifle which is capable of semi-automatic, 3-round burst and fully automatic fire. It has a cyclic rate of fire of around 700–900 rounds per minute.

The MSBS-5.56 features fully ambidextrous controls and Picatinny rail, and it may also be fed from standard STANAG magazines.^[18]

The following variants were designed based on the requests from the Polish Armed Forces to replace currently used firearms such as the AKM, FB Beryl, FB Mini-Beryl, and Pallad grenade launcher.

MSBS Grot C

The MSBS Grot C (Polish: klasyczny) is the classic configuration of the MSBS-5.56, chambered in either 5.56×45mm NATO or 7.62×39mm cartridge with a folding and retractable stock.^[28]

MSBS Grot A0

1,000 units were produced in the initial production of the MSBS-5,56 A0.

MSBS Grot A1

First production batch, also known as the “MSBS-5,56 A1“: modified charging handle and additional strap mount point on the picatinny rail.^[29]

MSBS Grot A2

Second production batch, also known as the MSBS-5,56 A2: longer handguard to cover the gas block, reinforced firing pin for dry fire practice, improved pistol grip and buttstock.^[30]

MSBS Grot A3

The MSBS Grot A3 was publicly presented at the Grotowisko 2024 small-arms conference, held in Zegrze from June 22 to 23, 2024.^[31] Its development was based on lessons learned from the conflict in Ukraine.^[32]

MSBS Grot R

The MSBS Grot R (Representative) is a manual repeating rifle variant of the MSBS Grot designed to be used as a ceremonial rifle by the Representative Honor Guard Regiment of the Polish Armed Forces, which has been adapted to fire blanks and withstand drills. With the modularity of the MSBS Grot, the barrel can be swapped to fire live ammunition.

MSBS Grot S

The MSBS Grot S is a civilian semi-automatic only variant of the MSBS Grot that lacks the bayonet-mount, and is available in 4 different barrel lengths for the .223 Remington: 10.5-, 14.5-, and 16-inch and only in 16-inch for the 7.62×39mm.^[33]

• Poland:
  • Polish Armed Forces, 184,000 planned by 2026.^[36][37]
  • Territorial Defence Force, 53,000 in 2017.^[36]
• Rwanda: On September 1, 2023, PGZ concluded a contract for the supply of MSBS Grot rifles with an unspecified East-Central African country.^[38] On January 31, 2024, the Defense24 portal listed Rwanda as the recipient of Polish rifles, but it is not certain whether the deliveries concern Grot or other rifles.^[39] In 2024, photos circulated on the web showing a Rwandan soldier with a 7.62x39 Grot fitted with a GP grenade launcher.^[40]
• Ukraine: 10,000 Grot C16 FB-M1 and -M2 variants were donated to the Ukrainian Armed Forces during the 2022 Russian invasion of Ukraine.^[1] In 2023, it was announced that an unspecified number of Grot C16 M2 variants had been ordered by Ukraine, but later on such claims have been denied.^[41][42]
• United States: Unknown quantity sold to Special Operations Command (USSOCOM).^[43]

• Adaptive Combat Rifle
• Beretta ARX160
• SIG MCX