Saab Bofors Dynamics CBJ - MS The CBJ - MS PDW is a Swedish submachine gun of the private arms - making company CBJ Tech AB and designed by Bertil Johannson . Description . The CBJ - MS personal defense weapon ( provisionally known during early 2000s as SAAB - Bofors CBJ - MS PDW ) is a brainchild of a Swedish arms designer Bertil Johannson , who established a private arms - making company CBJ Tech AB , which is located in Sweden . The CBJ - MS stands for ' CBJ Modular System ' . The SAAB - Bofors association was temporary , as this Swedish military industry corporation briefly sponsored this project during early 2000s , when British military expressed their interest in CBJ - MS system as a possible Personal Defense Weapon . For various reasons British interest in CBJ - MS quickly declined , ad SAAB - Bofors withdrew from the project , but the CBJ Tech company still continues development of this interesting weapon ( gun + ammunition ) system . The core of the CBJ - MS system is its special ammunition , nominally marked as 6 , 5x25 , which fires a variety of high - velocity projectiles . The primary loading is a saboted sub - caliber tungsten projectile , with caliber of 4mm ( 0 . 16 " ) and weight of 2 gram ( 31 grain ) . This armor - piercing projectile is enclosed into lightweight polymer sabot , and when fired from 200mm ( 8 " ) submachine gun barrel , muzzle velocity is as high as 830 m / s ( 2723 fps ) . This provides significant armor penetration , defeating standard CRISAT target at 230 meters or 7mm rolled steel armor at 50 meters . For use against unprotected targets , CBJ offers a spoon - tipped sub - caliber 4mm bullets , which will readily tumble upon impact with the body , to cause significant wound cavity . Same cartridge case also can be loaded with full - caliber 6 . 5mm bullets of various design . It must be noted that 6 . 5x25 CBJ ammunition can be used in a variety of weapons , originally chambered for 9x19 ammunition , with just replacement of the barrel and return springs , as the CBJ case is based on 9x19 cartridge case stretched forward and necked down to 6 . 5mm . The CBJ - MS Personal Defense Weapon / PDW is a blowback - operated , selective fire submachine gun which is broadly based on the Israeli UZI submachine gun . Barrel of CBJ - MS PDW is rifled , and can be easily removed from the gun for maintenance or replacement ( with barrel of same or alternate caliber ) . CBJ - MS PDW fires from open bolt in standard configuration , but an alternative bolt system with separate firing pin can be installed for firing from closed bolt ( for higher first - shot accuracy ) . Firing mode ( single shots or full automatic ) is selected by the pull on the trigger - short pull results in single shots , and full - length pull results in automatic fire . Charging handle is located on the back of the weapon , is fully ambidextrous and does not move when gun is fired . Magazine is inserted into pistol grip , and a spare box magazine can be carried inserted into the front grip . Standard magazine is of box type , holding 20 or 30 rounds , but a high - capacity 100 - round drum magazine is also developed for special applications . CBJ - MS PDW is equipped with adjustable open sights , and a Picatinny rail is provided on the top of receiver for installation of various optical sights . CBJ - MS PDW is equipped with retractable shoulder stock made from steel wire , and can be fitted with detachable bipod .