The first of the famous Bofors automatic guns placed into service, the 40 mm L/43 ubåtsautomatkanon Model 1932 (submarine automatic cannon) was developed from an early version of the Bofors 40 mm L/60 but with a shorter barrel and modified for submarine use. The gun and mounting was designed to be lowered into a water-proof tubular compartment under the decking for stowage. This was accomplished by elevating the gun to 90 degrees and then folding the fire-control handles and spent-cartridge chute up against the gun as can be seen in the photographs at right.
This weapon used the same ammunition as did the 40 mm L/60 gun but with a reduced propellant load.
Non-folding single and twin mounts were produced and exported to Poland, but the Royal Swedish Navy used only the single folding mount.
The last Swedish submarine armed with this gun was decommissioned in 1966.
|Designation||40 mm ubätsautomatkanon L/43 M/32|
|Ship Class Used On||Sweden:
Sjölejonet and Neptun classes
|Date Of Design||1930|
|Date In Service||1932|
|Gun Weight||243 lbs. (110 kg)|
|Gun Length||about 67.7 in (1.72 m)|
|Twist||Increasing RH twist|
|Rate Of Fire||120 to 140 rounds per minute cyclic
80 to 90 rounds per minute practical
- ^Six twin 40 mm mountings were delivered to Poland in 1937, at least two of which were 40 mm L/43 and the remainder 40mm L/60. The two 40 mm L/43 mountings were given to Blyskawica which carried them until rearmed in Britain with 40 mm L/60 guns in either 1940 or 1941. Other Polish ships were armed with Bofors guns including the minelayer Gryf and the submarines Orzel and Sep but it is not known if these were 40 mm L/43 or L/60 guns.
|Projectile Types and Weights||AB 40 mm L/43 HE-T: 2.05 lbs. (0.93 kg) 1a 2a|
|Weight of Complete Round||about 4.41 lbs. (2.0 kg)|
|Bursting Charge||HE-T: about 0.150 lbs. (0.068 kg) TNT|
|Projectile Length||7.25 in (18.4 cm)|
|Complete Round Length||17.60 in (44.7 cm)|
|Cartridge Case Type, Size and Empty Weight||Brass, 40 x 311R, 1.93 lbs. (0.88 kg)|
|Propellant Charge||0.485 lbs. (0.220 kg)|
|Muzzle Velocity||2,297 fps (700 mps)|
|Approximate Barrel Life||N/A|
|Ammunition stowage per gun||N/A|
|Max Horizontal Range
|about 4,800 yards (4,370 m)|
|Max Possible Horizontal Range
|about 10,900 yards (9,980 m)|
|Max Vertical Range
|about 14,650 feet (4,460 m)|
|Designation||Sweden Single Folding Mounts: Sjölejonet (2) and Neptun (1): N/A
Poland Twin non-Folding Mounts: Blyskawica (2): 40 mm L/43 Model 1937
|Weight||Single Mount: about 1,984 lbs. (900 kg)
Twin Mount: 6,173 lbs. (2,800 kg)
|Elevation||-10 to +90 degrees|
"The Bofors Gun" by Terry J. Gander
30 December 2017 - New datapage
05 March 2018 - Converted to HTML 5 format and added photograph of Polish guns