Naval Systems

Bofors 375 mm rocket launcher

Also known as
  • Bofors M/50
  • Bofors 375mm M/50
  • M/50 375mm anti-submarine rocket launcher
  • 37,5 cm aurakpjäs M/50
  • 37.5 cm aurakpjäs M/50
  • Bofors B2
  • Bofors B4
  • Bofors SR-375A
  • Mle 54
  • Creusot-Loire Modèle 54
  • Mitsubishi Type 71
  • Type 71 Bofors rocket launcher
  • 375 mm anti-submarine rocket launcher
  • 375 mm ASW rocket launcher

The Bofors 375 mm rocket launcher is a Swedish shipboard anti-submarine rocket-depth-charge system developed after World War II and fielded in two-, four-, and six-tube forms. The M/50 family tied sonar-directed fire control to an unmanned powered mount, below-deck ammunition handling, and 375 mm rockets, while license and derivative production by Creusot-Loire and Mitsubishi spread the system across French, Japanese, German, Dutch, Swedish, and export warship fits.

Bofors 375 mm rocket launcher, Shipboard anti-submarine rocket launcher, Naval Systems
Image source: File:Anti-submarine rocket launcher 375 mm model 1972-IMG 4174.JPG
Profile / Specs

Specifications

Caliber
375 mm
Launch tubes
2, 4, or 6
Tube length
3.6 m on B4 and B2 launchers
Rate of fire
1 rocket per second
Mount
Unmanned powered mount with below-deck ammunition handling room
Ammunition
375 mm rocket-powered anti-submarine depth charges
Fire control
Sonar input with electro-mechanical or digital predictors
Range
About 0.4-3.6 km depending on rocket type; Nelli reaches about 3.62 km
Depth setting
Hydrostatic fuse setting to about 250 m
Warhead
High explosive; Erika listed with 107 kg Hexotonal and Nelli with 80 kg Hexotonal
Reloads
24 to 48 rounds depending on launcher; 30 to 72 rounds on Modèle 54 ship fits
B4 reload cycle
Four tubes reloaded in about 3 minutes
B4 ammunition stowage
48 rounds per launcher
B2 reload cycle
Two rounds reloaded in about 30 seconds
B2 ammunition stowage
24 rounds per launcher
Traverse
B4: 260 degrees; B2: 360 degrees
Elevation
B4: -15 to +90 degrees; B2: 0 to +90 degrees
B4 weight
About 7.5 t
B2 weight
About 3.98 t without ammunition
Launcher And Rocket Family

The launcher family was built around ahead-thrown 375 mm rocket depth charges rather than guided torpedoes. Ship sonar fed the fire-control system, the powered mount laid the tubes in train and elevation, and the reload machinery below deck fed the unmanned launcher after firing.

Fire-control chain

Sonar input drove electro-mechanical predictors in early systems and digital fire-control equipment in later installations, with range set by launcher elevation and the selected rocket type.

Ammunition development

Mimmi, Erika, Flora, and Nelli rockets shared the 375 mm launcher family while differing in range, weight, warhead, and fuse arrangements; Nelli added a longer-range profile and proximity fuse.

Ship integration

The visible mount was only part of the system; the ammunition room and loading gear below deck shaped whether a ship carried the B4, B2, or French sextuple installation.

Rocket Types

The launcher family fired several 375 mm rocket-depth-charge types. Range depended on rocket type and launcher elevation, while later ammunition improved fuzing and reach.

RocketRangeWarhead and fuse notes
Mimmi / M/50About 0.38-0.83 kmOriginal 250 kg rocket-depth charge; public reference data lists a high-explosive warhead over 100 kg and probable impact fuzing.
ErikaAbout 0.65-1.63 km250 kg rocket with a 107 kg Hexotonal warhead and Stidar time/impact fuse.
FloraAbout 1.4-2.2 kmIntermediate-range rocket listed in launcher-family range tables; the checked sources do not publish a consistent warhead and fuse description.
NelliAbout 1.58-3.62 km230 kg rocket with an 80 kg Hexotonal warhead and Zambo proximity/impact fuse.
Variants

The Bofors M/50 family used the same 375 mm rocket-depth-charge concept across launcher mounts tailored for different ship sizes and navies.

VariantConfigurationDesignation notes
Bofors B4Quadruple launcher

The original Bofors launcher entered service in 1956 as the M/50 and later B4, with four tubes, a below-deck semi-automatic loader, nominal storage of 48 rockets per launcher, and a three-minute reload cycle for all four tubes.

Sources: Weaponsystems: Bofors M/50

Creusot-Loire Modèle 54French sextuple launcher

Creusot-Loire developed the six-tube Modèle 54 for French ships, using one mount to approach the firepower of two B4 launchers and carrying ammunition loads that varied by class.

Sources: Weaponsystems: Bofors M/50

Bofors B2 / SR-375ATwin launcher

The compact B2 twin launcher, also identified by Weaponsystems.net as SR-375A, appeared in the early 1970s with 360-degree traverse, 24-round ammunition storage, and a two-round reload cycle of about 30 seconds for smaller combatants.

Sources: Weaponsystems: Bofors M/50

Mitsubishi Type 71Japanese licensed B4 launcher

Japan licensed the B4 launcher through Mitsubishi Heavy Industries; Weaponsystems.net lists Type 71 as the Japanese-service designation for the B4 mount.

Sources: Weaponsystems: Bofors M/50

Carrier Platforms

The launcher is documented aboard D'Estienne d'Orves-class avisos in a remote-controlled sextuple fit with below-deck reloads.

CarrierCarrier typeCarriage evidence
D'Estienne d'Orves-class aviso, Aviso / light corvette, Naval SystemsD'Estienne d'Orves-class avisoAviso / light corvette

Seaforces says the class mounts one remote-controlled sextuple 375 mm rocket launcher with 30 reloads carried in a magazine beneath the aft deckhouse.

Sources: Seaforces: D'Estienne d'Orves class Corvette Aviso French Navy Marine

Documented Ship Fits

Public naval references tie the launcher family to several Cold War surface-combatant branches. Sweden and the Netherlands used B4 quadruple launchers on destroyers; France used the sextuple Modèle 54 on D'Estienne d'Orves-class and other ships; Japan used Mitsubishi-built Type 71 launchers; and the lighter B2/SR-375A appeared on smaller corvette and frigate classes.

B4 / Type 71 branch

Weaponsystems.net lists Swedish Halland, Dutch Friesland and Holland, German Hamburg, and multiple Japanese destroyer or training-ship classes among B4 or Type 71 users.

French sextuple branch

The Modèle 54 fit is documented on D'Estienne d'Orves-class avisos and other French or Belgian classes, with the A69 fit later removed from French ships during patrol conversion.

B2 export branch

The twin launcher is listed for smaller designs including Fatahillah, Kasturi, Niterói, Descubierta, Erinomi, and later Nilgiri-class fits.

Timeline

Bofors 375 mm rocket launcher Key Events

  1. M/50 development begins

    Weaponsystems.net places the launcher-family development period from 1948 to 1954, with the related 375 mm rocket-depth-charge work beginning in the same postwar period.

    Sources: Weaponsystems: Bofors M/50, Weaponsystems: Bofors 375mm M/50

  2. B4 enters service

    The B4/M/50 quadruple launcher entered service in 1956 and became the baseline Bofors mount used by early Swedish and Dutch destroyer fits.

    Sources: Weaponsystems: Bofors M/50

  3. French Modèle 54 appears

    Creusot-Loire introduced the Modèle 54 sextuple launcher for French service, creating the six-tube branch later associated with A69 avisos and other French ships.

    Sources: Weaponsystems: Bofors M/50

  4. Japanese license production arranged

    Missilery.info states that Mitsubishi contracted with Bofors in 1968 to manufacture the complex under license for Japanese naval service.

    Sources: Missilery.info: 375mm Bofors anti-submarine reactive complex

  5. Bofors B2 twin launcher introduced

    Bofors introduced the B2 twin launcher for smaller ships, reducing mount weight while improving the reload cycle compared with the older four-tube installation.

    Sources: Weaponsystems: Bofors M/50

  6. Nelli rocket enters the family

    The Nelli 375 mm rocket-depth-charge variant brought a longer range band and proximity-fuse option while using a lighter high-explosive warhead.

    Sources: Weaponsystems: Bofors 375mm M/50

  7. Type 71 refits reach Japanese destroyers

    Japanese-service Type 71 launchers, locally produced by Mitsubishi Heavy Industries, replaced Weapon Alpha on some JMSDF destroyer classes during 1970s refits.

    Sources: Weaponsystems: Bofors M/50, Gyrodyne Helicopters: JMSDF Destroyers

Media

Bofors 375 mm rocket launcher Videos

Bofors 375 mm rocket launcher Images

Bofors 375 mm rocket launcher, Shipboard anti-submarine rocket launcher, Naval Systems - view 1
Source: File:Anti-submarine rocket launcher 375 mm model 1972-IMG 4184.JPG
Bofors 375 mm rocket launcher, Shipboard anti-submarine rocket launcher, Naval Systems - view 2
Source: File:HMS Smaland, anti-submarine weapons.JPG
Bofors 375 mm rocket launcher, Shipboard anti-submarine rocket launcher, Naval Systems - view 3
Source: File:375 mm Anti-Submarine-Rocket-Launcher-Bofors-Destroyer FGS Hessen (1).jpg
Bofors 375 mm rocket launcher, Shipboard anti-submarine rocket launcher, Naval Systems - view 4
Source: File:375 mm Anti-Submarine-Rocket-Launcher-Bofors-Destroyer FGS Hessen (1).jpg
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Sources

Weaponsystems: Bofors M/50Publisher: Weaponsystems.net | Note: Supports the launcher family designation, Swedish origin, production countries, operational history, launcher layout, variants, platform families, and general specifications. | Accessed: 2026-07-05Weaponsystems: Bofors 375mm M/50Publisher: Weaponsystems.net | Note: Supports the 375 mm rocket family, tube-count variants, and range and fuse development for the launcher family. | Accessed: 2026-07-05Missilery.info: 375mm Bofors anti-submarine reactive complexPublisher: Missilery.info | Note: Supports system composition, the shallow-water anti-submarine role, Bofors development and production chronology, launcher reload mechanics, and rocket range bands. | Accessed: 2026-07-05Seaforces: D'Estienne d'Orves class Corvette Aviso French Navy MarinePublisher: seaforces.org | Note: Supports the launcher's documented fit aboard D'Estienne d'Orves-class avisos, including the remote-controlled sextuple mount and below-deck reload magazine. | Accessed: 2026-07-05File:Anti-submarine rocket launcher 375 mm model 1972-IMG 4174.JPGPublisher: Wikimedia Commons | Note: Supports the primary image and its provenance. | Accessed: 2026-07-05File:Anti-submarine rocket launcher 375 mm model 1972-IMG 4184.JPGPublisher: Wikimedia Commons | Note: Supports the gallery image and its provenance. | Accessed: 2026-07-05File:HMS Smaland, anti-submarine weapons.JPGPublisher: Wikimedia Commons | Note: Supports gallery image provenance for the Bofors launcher installation on the Swedish destroyer HMS Småland. | Accessed: 2026-07-05File:375 mm Anti-Submarine-Rocket-Launcher-Bofors-Destroyer FGS Hessen (1).jpgPublisher: Wikimedia Commons | Note: Supports gallery image provenance for a 375 mm Bofors launcher reload scene aboard the German destroyer Hessen. | Accessed: 2026-07-05File:375 mm Anti-Submarine-Rocket-Launcher Bofors.jpgPublisher: Wikimedia Commons | Note: Supports gallery image provenance for a Bofors 375 mm launcher photographed at the Wehrtechnische Studiensammlung Koblenz. | Accessed: 2026-07-05Gyrodyne Helicopters: JMSDF DestroyersPublisher: Gyrodyne Helicopter Historical Foundation | Note: Supports the Japanese Type 71 Bofors launcher fit on JMSDF destroyer classes. | Accessed: 2026-07-05