Specifications

Caliber:	40 mm
Weight:	4,367 pounds
Crew:	Dependent upon use
Shell:	Complete round: L/60 40×311mmR (1.57 in) L/70 40×364mmR
Maximum Firing Range:	23,490 feet
Caliber:	40 mm L/60-70
Carriage:	1,151 pounds
Elevation	55 degrees/second
Traverse:	Full 360 degreees
Rate of fire:	120 Rounds/minute
Status:	Static display
Owner:	Estrella Warbirds Museum

History

The Bofors 40 mm Automatic Gun L/60 (often referred to simply as the "Bofors 40 mm gun", the "Bofors gun" and the like, is an anti-aircraft autocannon, designed in the 1930s by the Swedish arms manufacturer AB Bofors. The gun was designed as an intermediate anti-aircraft gun, filling the gap between fast firing close-range small calibre anti-aircraft guns and slower firing long-range high calibre anti-aircraft guns, a role which previously was filled by older outdated guns. The Bofors 40 mm L/60 was for its time perfectly suited for this role and outperformed competing designs in the years leading up to World War II in both effectiveness and reliability.

It entered the export market around 1932 and was in service with 18 countries by 1939. Throughout World War II it became one of the most popular and widespread medium-weight anti-aircraft guns. It was used by the majority of the western Allies and some Axis powers such as Nazi Germany and Hungary.

In the post-wwii era, the Bofors 40 mm L/60 design was not suitable for action against jet-powered aircraft, so Bofors developed a new 40 mm replacement design with significantly more power — the Bofors 40 mm Automatic Gun L/70, also known under the generic name 'Bofors 40 mm gun' — which was adopted by many nations during the Cold War and was selected as NATO-standard in November 1953.The Bofors 40 mm L/60 would however continue to see service long after becoming obsolete as an anti-aircraft weapon due to the massive number of surplus guns from WWII, and a small number of Bofors 40 mm L/60 guns remain in service today. Some weapons saw action as late as the Gulf War and Yugoslav Wars.

In order to supply both the Army and Navy with much greater numbers of the guns, Chrysler built 60,000 of the guns and 120,000 barrels through the war, at half the original projected cost, and filling the Army's needs by 1943.

Over the lifetime of the production, their engineers introduced numerous additional changes to improve mass production, eventually reducing the overall time needed to build a gun by half; most of these changes were in production methods rather than the design of the gun itself.

There were many difficulties in producing the guns within the United States, beyond their complexity (illustrated by the use of 2,000 subcontractors in 330 cities and 12 Chrysler factories to make and assemble the parts). The drawings were metric, in Swedish and read from the first angle of projection, with lower precision than needed for mass production. Chrysler had to translate to English, fix absolute dimensions, and switch to the third angle of projection.

"It should be noted that the USN considered the original Bofors Model 1936 design to be completely unsuitable for the mass production techniques required for the vast number of guns needed to equip the ships of the US Navy. Firstly, the Swedish guns were designed using metric measurement units, a system all but unknown in the USA at that time. Worse still, the dimensioning on the Swedish drawings often did not match the actual measurements taken of the weapons.

Secondly, the Swedish guns required a great deal of hand work in order to make the finished weapon. For example, Swedish blueprints had many notes on them such as "file to fit at assembly" and "drill to fit at assembly," all of which took much production time in order to implement.

Thirdly, the Swedish mountings were manually worked, while the USN required power-worked mountings in order to attain the fast elevation and training speeds necessary to engage modern aircraft. Fourthly, the Swedish guns were air-cooled, limiting their ability to fire long bursts, a necessity for most naval AA engagements.

Finally, the USN rejected the Swedish ammunition design, as it was not bore safe, the fuze was found to be too sensitive for normal shipboard use and its overall design was determined to be unsuitable for mass production. US manufacturers made radical changes to the Swedish design in order to minimize these problems and as a result the guns and mountings produced in the USA bore little resemblance their Swedish ancestors."