Among all the weapons used by the warring parties of WW2, one family of anti aircraft guns really stood out, the Bofors 40mm. Credited with shooting down more aircraft than any other AA gun of their time. The allies used these medium caliber guns to provide their ships with very effiective defense from aircraft.
The Bofors 40mm was first created when the Swedish navy approach the company Bofors to create a replacement anti aircraft gun for the British made guns they bought in 1922. The company signed a contract in 1928 and in the 19th century, produced their first prototype, it was a smaller version of a 57mm semi-automatic gun produced to developed to fight against torpedo boats. Although the Bofor’s variant had a smaller caliber, it had a semi-automatic loading system. That prototype was abandoned in 1929 due to rpoblems with improving the gun’s rate of fire. A new mechanism was developed in 1930 which after successful testing, the company went in that direction with a new prototype. When Krupp bought one third of the company’s shares and updating the equipment and metallurgy, the project was kept secret. The prototype was completed by November of 1931 with changes to the feeding mechanism.
When British and American engineers studied the Bofors L60, they were impressed with the high efficency of the gun outperforming anything they had at the time. In comparison to the british QF 2-pounder and the american chicago piano, the bofors L60 fired heavier 894 gram shells and additionally a faster rate of fire than the QF-2 pounder. The barrage of shells produced by this gun was astounding, creating a wall of fire that almost no aircraft at that time could get through.
Great Britian and the USA purchased a licenses to produce the gun themselves but they had difficulties with the gun intended to be assemled by hand, the drawings were in metrics, and most of the parts were labeled “file to fit at assembly”, as a result, the guns look many man-hours to complete. The USA engineers also had to translate the drawings from swedish to english as well as convert metrics to imperial meaurements.
The Bofors L70 is the post WW2 successor to the L60, Having been modernized to fire heavier but also lighter shells at a faster fire rate.
Today, many examples of bofors are preserved on board museum ships and they are still in service in some navy as well as the AC-130 gunship.