|MSBS Radon||MSBS-B bullpup-eng|
|Full text name||Автомат (штурмовая винтовка) MSBS Radon (Польша)||MSBS-B bullpup|
|Caliber cartridge||5.56x45 NATO, .223 Remington||5.56x45 NATO, .223 Remington|
|Overall length, mm||900||670|
|Length, folded, mm||670||—|
|Barrel length, mm||406||406|
|Weight empty, kg||3.65||3.55|
|Magazine capacity, rounds||30||30|
|Cyclic rate of fire, rounds/min||700||700|
MSBS Radon modular weapon system is an indigenous development of Polish Military Technical Academy (Wojskowa Akademia Techniczna) and Fabryka Broni „Lucznik” – Radom weapons factory. MSBS stands for “Modułowy Systema Broni Strzeleckiej” – modular small arms system. It is scheduled to enter initial production for Polish army trials late in 2014. As of now, MSBS system consist only of two weapons – MSBS-5.56B Radon-B bullpup assault rifle, intended for Special Forces, and MSBS-5.56K Radon-K standard configuration rifle intended for infantry and other units. Future versions of the MSBS also may include heavy barreled Designated Marksmen rifle and Squad Support Weapon (light machine gun).
The backbone of MSBS system is an inverted U-shaped receiver, made from aluminum alloy. This receiver, along with bolt group, return spring, barrel and gas system are common for both current versions of MSBS rifles.
MSBS is operated using short stroke gas piston, located above the barrel, and its gas system has manual gas regulator. Breech lock is achieved by a conventional rotary bolt with seven radial lugs that lock into the barrel extension. Ejection windows are made on both sides of the receiver, and weapon can be set up to eject to either side; this requires partial disassembly of the gun and installation of the ejection port cover on the side opposite the “active” ejection window. Non-reciprocating charging handles are located on both sides of the receiver.
Polymer stocks are made integral with magazine and trigger unit housings (pistol grips are separate Ar15/M16-compatible parts), and available in two versions – standard (with side-folding, telescoping shoulder stock) and bullpup (with fixed buttplate). Both versions feature ambidextrous safety / fire mode selectors located at the top of the pistol grip, and ambidextrous magazine release buttons located in front of the trigger guard. Bolt stop release buttons are located on the underside of the stock, behind the magazine housing. Both stock versions are interchangeable and attach to receiver using cross-pins. Polymer forends also interchangeable. MSBS rifles are fed from STANAG-compatible (M16-type) magazines. Sighting equipment is installed using Picatinny rail at the top of the receiver. Both MSBS-5.56B Radon-B bullpup and MSBS-5.56K Radon-K standard rifle can mount proprietary knife-bayonet (above the barrel) and specially designed 40mm grenade launcher (below the barrel).