The WAT-FB Grot (a Polish word referring to the tip of various pointed weapons such as arrows, darts and javelins), formerly known as the MSBS Radon or the MSBS-5.56 (Modułowy System Broni Strzeleckiej, English: modular rifle system), is a Polish assault rifle.

History[edit | edit source]

Research about a modern assault rifle for use by Polish forces was carried out from 2003 to 2006, with the research eventually culminating in the development of the MSBS. The rifle has been in development since December 2007 by WAT and FB Radom as part of a R&D program started by both parties; the target of the program was to culminate in the development of a modular small arms platform for use by the Polish Army, with a number of demonstrations held to showcase the weapons platform. Details of the project were only revealed in 2009.[1]

During development, the rifle was simply known as the MSBS; a competition was later held by Polish shooting magazine Strzał in collaboration with FB Radom to submit a name for the new weapon. The name that was chosen was Radon, with the winner of the competition given a tour around the FB Radon factory. After it was decided that the MSBS would be accepted into the Polish army, a new name for the weapon had to be created; this time, Grot was chosen as the new name of the weapon, named after General Stefan Rowecki, leader of the Polish Home Army.

Production of the weapon appears to have started in June 2014. The weapon intends to replace the AKM, AKMS and RPK and is supposed to complement the Beryl assault rifle. The weapon appears to have entered military trials in 2017. FB representatives stated at the 2015 SHOT Show that they were planning to open an additional factory in Texas and make the Grot available in the United States; this appears to have not come to fruition.

Programs similar to what was done for the MSBS program have also been conducted as part of Projekt TYTAN, another Polish military program aimed at developing the 21st century soldier, known as the "Land Warrior".

Design Details[edit | edit source]

The Grot is a modular system which has part interchangeability between its many variants, such as barrel changeability. This allows its user to adapt the weapon based on the situation they are in. The weapon has simplified logistics when compared to other rifles. The weapon has a common receiver design for both conventional and bullpup variants. Picatinny rails are standard on both configurations.

The weapon's receiver is made out of duralumin, and it is equipped with a two-position gas regulator. The weapon's bolt has seven locking lugs and is select fire. The weapon is also completely ambidextrous, with a variety of controls being placed on both sides of the weapon, in addition to there being two ejection ports, with the unused ejection port being covered by a dust cover to prevent dirt and debris from entering. The bolt of the weapon can also be altered so that it extracts cartridges to the left or right depending on user choice.

Not only does the gas regulator help to regulate the amount of gas used to fire the weapon, it also helps as a gas cut off system, which cuts off all flow to the piston, disallowing it to cycle automatically; this makes the Grot akin to that of a bolt-action rifle. This system is claimed to aid the user in not giving away their position when a suppressor has been fitted, as the sound of the weapon cycling could very well give away their position. The bolt locks open on an empty magazine.

Ammunition[edit | edit source]

The Grot takes a variety of cartridges, from 5.56×45mm NATO all the way to 7.62×51mm NATO.

Variants[edit | edit source]

Old nomenclature[edit | edit source]


Conventional variant chambered for 5.56×45mm NATO.


Bullpup variant chambered for 5.56×45mm NATO.


Conventional variant for ceremonial purposes, adapted to fire blanks.


Conventional variant chambered for 7.62×39mm.


Prototype battle rifle chambered for 7.62×51mm NATO.

New nomenclature[edit | edit source]

The Grot series of weapons use a new form of nomenclature. The new nomenclature is as follows: Grot (layout)(barrel length)(variant)FB-(series)

A legend for the new nomenclature is as follows:

  • C/B/R - layout (C = classic/conventional, B = bullpup, R = "representative model")
  • 10/16/20 - barrel length in inches
  • G, M, PS, S - "variant symbol" (G = grenade launcher, M = machine gun, PS = marksman rifle, the designation is omitted for a normal assault rifle, S = Semi-automatic)
  • FB - Fabryka Broni
  • Mx - series designation (x is a number, i.e. M1 = first series)

Under the new nomenclature, a weapon classified as Grot C16GFB-M1 shows that it is a Grot with a conventional layout, 16-inch barrel, has an underbarrel grenade launcher and is of the first production run or series.

Gallery[edit | edit source]

References[edit | edit source]

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