CBJ MS: A Swedish Modular System for PDW

Swedish Soldier with CJB MS submachine gun Swedish Soldier with CJB MS submachine gun
Swedish Soldier with CJB MS submachine gun (Photo: CBJ Tech AB)

The CBJ MS, also known as the Modular System, is an innovative personal defense weapon (PDW) designed by Bertil Johanson, a renowned Swedish arms designer, and founder of CBJ Tech AB. Unveiled in the early 2000s, the CBJ MS was specifically created for non-frontline troops, commanders, drivers, crews, pilots, medical teams, and other support personnel. This compact firearm boasts exceptional features and is currently in the final stages of development, although it has yet to receive any production orders.

Design and Operation

The CBJ MS operates on a blowback mechanism and offers selective fire capabilities. Notably, it can be equipped with a replacement bolt group, allowing the firearm to fire from a closed action. The design of the CBJ MS draws inspiration from the well-known Israeli UZI submachine gun while introducing several innovative modifications.

All parts of the weapon are made of stainless steel or polymers. This makes the weapon very resistant to corrosion, not only from salt water but also from chemical agents used for decontamination. The weapon is blowback-operated and fires from an open bolt. With a replaceable bolt group, it can also fire from a closed bolt with the help of a floating firing pin. The weapon’s good ergonomics, advanced priming ignition, low rate of fire, and mechanical design of the bolt give very good stability when firing, also at burst firing. The rugged, simple design makes it extremely reliable.

CBJ MS submachine gun receiver and drawing
CBJ MS submachine gun receiver and drawing (Photo: CBJ Tech AB)

The CBJ Modular System is mainly intended as a Personal Defence Weapon for Close Quarter Battle with users like Special Forces, SWAT, units specialized in urban warfare, Security Forces, etc. It is very rugged and designed to fully function under harsh conditions, from arctic to desert to jungle environments.

Ammunition and Performance

The CBJ MS utilizes specially developed 6.5x25mm high-velocity ammunition, which surpasses the performance of standard 5.56mm NATO and, in some cases, even 7.62mm NATO rounds. This advanced round offers exceptional armor penetration capabilities, demonstrated by its ability to completely penetrate a standard CRISAT armored vest at a range of 230 meters during trials. In addition to the armor-piercing round, the CBJ MS supports various cartridges for various targets and training purposes.

Advantages over Competitors

The CBJ MS positions itself as a superior alternative to other personal defense weapons, such as the FN P90 and HK MP7. This system excels in close combat and self-defense scenarios, proving highly effective against lightly armored vehicles. It’s versatility and exceptional performance make it an ideal choice for a wide range of military and law enforcement personnel.

Interchangeable Ammunition and Compatibility

The 6.5x25mm CBJ cartridge shares similar dimensions with the popular 9x19mm Parabellum round, allowing many existing 9x19mm pistols and submachine guns to be re-barreled and utilize the 6.5x25mm CBJ ammunition. This interchangeability enhances the flexibility and adaptability of the CBJ MS. Furthermore, during training exercises, the CBJ MS can utilize the widely available 9x19mm ammunition.

CJB MS submachine gun with all parts explained
CJB MS submachine gun with all parts explained (Photo: CBJ Tech AB)

Ease of Use and Maintenance

The CBJ MS features a two-step trigger system, enabling users to choose between single shots or automatic fire with a short or full-length pull, respectively. Safety features include a manual safety button over the trigger guard and a built-in automatic grip safety. The weapon’s charging handle, positioned at the rear, remains immobile during firing. Field stripping the CBJ MS is a straightforward process, requiring no tools, as it can be disassembled into seven parts. The barrel can be easily replaced or maintained, ensuring optimal performance and longevity.

Magazines and Accessories

The CBJ MS incorporates a magazine well within its pistol grip, accommodating standard Carl Gustaf SMG magazines. Users have the option of using either 20- or 30-round box-type magazines. An additional magazine can be carried and inserted into the front grip for rapid reloads. Furthermore, a high-capacity drum magazine, holding up to 100 rounds, is available for extended engagements.

Stripped parts of CBJ MS SMG
Stripped parts of CBJ MS SMG (Photo: CBJ Tech AB)

The CBJ MS is equipped with adjustable open sights for precise targeting. A Picatinny-type rail mounted on the receiver enables the attachment of various scopes and night vision sights, enhancing accuracy and visibility in low-light conditions. Optional Picatinny-type accessory rails on the sides provide additional customization opportunities, enabling users to attach accessories such as flashlights and laser pointers. The front grip can also be replaced with various accessories to meet individual preferences and mission requirements.

Versatility and Adaptability

The CBJ MS stands out not only for its exceptional performance but also for its versatility and adaptability. It features a retractable steel wire shoulder stock that enhances stability and control during firing. In addition, the firearm can be configured as a light support weapon by attaching a detachable bipod, expanding its functionality on the battlefield. Furthermore, the CBJ MS offers the option of equipping a sound suppressor, although it requires specialized subsonic ammunition to maintain optimal effectiveness.


The CBJ MS can be transformed into a light support weapon by attaching a detachable bipod and utilizing a 100-round drum magazine. In this configuration, it becomes a highly capable assault weapon, ready to meet the demands of intense engagements.

Technical specifications

Country of origin:Sweden
Manufacturer:CBJ Tech AB
Caliber:6.5×25 mm
Weight (unloaded):2.8 kg
Length:565 mm
Length (with folded stock):363 mm
Barrel length:200 mm
Muzzle velocity:830 m/s
Cyclic rate of fire:700 rpm
Practical rate of fire:30 – 100 rpm
Magazine capacity:20,  30, 100 rounds
Range of effective fire:up to 400 m
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