FB MSBS Grot

Lore & Background

The MSBS program began in 2007 by the Military University of Technology (WAT) in Warsaw with cooperation from Fabryka Broni Radom, designed to replace the FB Beryl as the standard-issue service rifle of the Polish Armed Forces. During initial tests, the MSBS-5.56 was compared with the Heckler & Koch HK416 for barrel and hand-guard overheating during intensive firing, yielding better results despite a relatively light and longer barrel profile. Additional tests showed the MSBS was less susceptible to jamming with lower quality ammunition or insufficient maintenance, and had more manageable recoil in fully automatic compared to the FB Beryl, HK416, FN SCAR-L, and CZ BREN 2.

The MSBS Grot was developed in two configurations: the conventional MSBS Grot C and the bullpup MSBS Grot B, both using the same locking mechanism with modular interchangeability of parts and accessories. The rifle features fully ambidextrous controls, Picatinny rails, and barrel changeability similar to the Steyr AUG, allowing a soldier to adapt the rifle for different roles. Following adoption by the Polish military, the Grot moniker was added in honor of Home Army commander General Stefan "Grot" Rowecki; the Polish word "Grot" translates to "arrowhead" or "spearhead."

During the 2022 Russian invasion of Ukraine, 10,000 Grot C16A2s were sent to the Ukrainian military. In May 2022, an agreement was concluded between the Polish Armaments Group and an undefined East African country for supply of MSBS Grot rifles chambered in 7.62×39mm. In January 2025, a photo appeared showing an MSBS Grot C chambered in 7.62×39mm captured by soldiers of the Democratic Republic of the Congo from M23 rebels.

Reader's Guide

The MSBS Grot represents a significant step in Polish small arms development, being the first Polish rifle fully compliant with NATO standards and designed with modularity as a core principle. Its modular system allows a soldier to sacrifice one standard assault rifle to quickly repair a light machine gun during a firefight, and barrel changeability enables conversion between carbine and designated marksman roles, reducing the need for specialized weapons within an infantry squad. The MSBS-7.62N project, later designated Grot 762N, began in late 2015 as a designated marksman variant.

The M2 upgrade addressed issues found on early production models, introducing a longer upper receiver with M-LOK compatible handguard, reinforced components, and a FB-made polymer translucent magazine. The A3 variant, publicly presented at the Grotowisko 2024 conference, incorporated changes based on feedback from users and combat experience in Ukraine, including a shorter 14.5-inch barrel, redesigned stock mounting, and modifications to the gas system. In June 2026, the Armament Agency approved the A3's technical documentation and signed a production contract for approximately 46,000 MSBS GROT C14 FB-M1 A3 rifles. The MSBS Grot R is a manual repeating ceremonial variant for the Representative Honor Guard Regiment. On December 11, 2025, FB Radom announced ATF certification for import and sale of the MSBS GROT Pistol on the U.S. civilian market.

Did You Know?

• The MSBS Grot was developed in both conventional (C) and bullpup (B) configurations using the same locking mechanism.
• During comparative tests, the MSBS-5.56 outperformed the HK416 in barrel overheating resistance despite a lighter, longer barrel.
• 10,000 Grot C16A2s were sent to Ukraine during the 2022 Russian invasion.
• The Grot moniker honors General Stefan 'Grot' Rowecki, and the Polish word 'grot' means 'arrowhead' or 'spearhead.'