Updated 28 December 2013

Prototype Bofors gun made for the Swedish Navy ca. 1932
Wheeled carriage was for transporting the weapon between the range and the factory
Photograph copyrighted by Bofors

USN Air-cooled 40 mm single mounting
Sketch courtesy of Robert Stoner of Warboats.org

Side view of 40 mm Mark 1 gun in Mark 3 mounting
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USN Twin 40 mm Bofors Mount
Note the case discharge chutes at the right and the ejector chutes at the rear of the guns.  These provided a safe path for expended cartridges off the mount at any angle of elevation.
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USN Quad 40 mm Bofors Mount
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USN 40 mm Mark 1 gun assembly
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Crewmen feeding four-round HE-T/SD ammunition clips on USS Alaska CB-1 in 1945
U.S. Historical Center Photograph K-3740

Crewmen passing 40 mm HE-I-T/SD rounds on USS Alaska CB-1 in 1945
The clip that holds the rounds together can just be seen at the base of the cartridges
The rounds with green tips directly behind the crewman are HE-T/SD ammunition
U.S. Historical Center Photograph 80-G-K-3733

40 mm Single Mount on USS Sausalito PF-4
Note the safety rails, a common sight on ships with these manually operated mountings
U.S. Historical Center Photograph # NH 103339

40 mm Mark 1 air-cooled gun in Mark 3 mounting on unidentified PTF in May 1973
U.S. Navy Photograph No. DN-ST-88-07400

Twin 40 mm from the destroyer ORP Blyskawica
This weapon is now at the Polish Army Museum, Warsaw
Photograph copyrighted by Michal Kopacz

Bofors air-cooled twin mounting used on Polish submarine
This weapon is now at the Polish Army Museum, Warsaw
Photograph copyrighted by Michal Kopacz

Quad 40 mmm Bofors mount on USS Alabama BB-60
Photograph copyrighted by NavWeaps and Michael Fahlman

Wet-mount 40 mm Bofors on USS Mero SS-378
USN Photograph

British Hazemeyer 40 mm Mark IV
Note the Type 282 radar with its drive gearing, the analog computer and the rangefinder on the far right.  The boxes on the rear are for ready ammunition.  The Mark IV* was similar but eliminated the rangefinder in favor of an additional counterweight and used a larger, stronger platform to mount the radar antenna.

British Mark V Mounting

British Mark V Mounting with front shield removed

British Mark VII Single Mounting
This mounting was in use well into the 1970s

British 40 mm Mark VII Mounting on HMS Sheffield in 1958
IWM photograph A 34015

British twin 40 mm STAAG Mounting (minus shield)

40 mm STAAG mounting being shown to Australian Naval Officers and munitions workmen
State Library of Victoria Image H98.105/3203

 German 4 cm/56 Flak 28
This picture was taken on the Prinz Eugen in Philadelphia, PA, USA
Note the 10.5 cm/65 SK C/33 in the background
USN Photograph

Twin 40 mm Bofors on Brazilian Barroso (ex-USS Philadelphia CL-41) in March 1951
USS Tuscaloosa CA-37 in background
U.S. Historical Center Photograph # 80-G-708174

USN 40 mm projectiles of World War II
Note that the AP M81 does not have a boattail and that the windshield apparently forms the bourrelet

 Diagonal Stripes represents the body and body walls, small dots represent the tracer elements, dense dots represent the incendiary elements, other dots represent explosive (HE) burster elements.  Explosive, incendiary and tracer elements were loaded in increments, as shown in the above sketches.

Cutaway view of USN M81A1 AP Round

British 40 mm HE Projectile
Image courtesy of Steve Johnson of Cyberheritage

Cutaway sketches of 40 mm ammunition

See Bofors

12 November 2008 - Benchmark
11 June 2010 - Added cutaway picture of complete M81A1 AP round
14 January 2011 - Added cutaway sketch
06 April 2011 - Added pictures of British Mark V twin mounting
28 January 2012 - Added picture of Polish twin mounting
16 June 2012 - Added picture of STAAG in Australia
28 December 2013 - Added picture of HMS Sheffield