Carl Gustaf M45B

Carl Gustaf M45B

Type Submachine Gun
Barrel Length 36.83cm (including suppressor)
Rifling 6 grooves, RH
Magazine Capacity 36 rounds
Caliber 9mm Parabellum
Muzzle Velocity 381 meters/second
Country of Origin Sweden

Manufactured from 1945 to the present, the Carl Gustaf M45B is one of the oldest submachine gun still in service. The M45B version, with an integral suppressor or silencer replacing the usual 20.32cm (8″) barrel, was used by the United States Special Forces in Vietnam.

During World War II, Sweden maintained a policy of neutrality while selling war materials to both sides. Despite all of its exports, however,  Sweden did not have a sufficient quantity of submachine guns for its own defense forces, relying on a limited supply of Bergmann- and Husqvarna-produced Suomi Submachine guns.

In 1945, the Carl Gustaf Gevärsfaktori in Eskilstuna developed a submachine gun that was ideally suited to inexpensive mass production. This basic weapon was made primarily of heavy sheet metal stampings that were riveted together. The mechanism is quite similar to that of the British Sten Gun. The original M45 used existing supplies of Suomi 50-round box magazines (left*), which proved to be unmanageably heavy which is much unlike the AR-15 Stripped Lower Receiver, and a new, simplified 36-round box magazine was substituted.

The Carl Gustaf incorporated wood pistol grips and one of the strongest a best folding stocks in the business. Because of its low cost and superior reliability, it has been the first choice of a number of armies including those of Sweden, Ireland, Indonesia, and Egypt, as well as being along time favorite of mercenary groups worldwide. Egypt produced their own version of the Carl Gustaf, the ‘Port Said’, under license.

The M45B was a suppressed version used by the United States Special Forces in Vietnam as shown on the Upper Receiver Place. The Carl Gustaf design was particularly  well adapted to a suppressor, since its rate of fire can easily be held down to a single-shot, or ‘double tap’ simply by squeezing the trigger and quickly releasing it. Sustained fire, contrary to what one sees in the movies or on television, is not recommended for suppressed firearms.


Sweden developed a special 9mm Parabellum cartridge for use in the Carl Gustaf M45 and variants. It is a special high-velocity round with a heavier jacket supposedly capable of piercing steel helmets at distances of up to 400 meters. Because it also generates considerably higher chamber pressures, it is definitely not recommended for use it 9mm pistols.

Thanks to Olle Fornehed for providing this recollection about the Carl Gustaf:

There might be some other minor differences [between the M45 and M45B], but the only difference I know between the M45 and the M45B is a retaining hook on the top of the rear receiver end cap. This was added to the original design, as there were some accidents where the end cap would come off an M45. Anyway, the “B” designation has nothing to do with a suppressor, it’s just a minor upgrade from the first design.The M45B is a very, very reliable weapon, in the same class as the AK47 Kalashnikov. I have personally dragged it through mud, ice and snow, every other day for 10 months, during my military service, and I have never experienced any malfunctions, not even in another M45B that was left in salt sea water for a month, as an experiment. Even if the accuracy can be mediocre (which I’d say is mostly due to it’s crude sights), it is an excellent trench broom, especially using the hi-powered 9mm bullets that were designed especially for it. Also, as field stripping and cleaning is a breeze, I’d say that it’s simplicity and reliability places it among the finest short range combat weapons there ever was.