The 40mm guns were produced at the begging of WWII. It was made to be an anti aircraft round. There were two versions made; for the navy on the sides of ships to stop dive bombing planes coming in, and also for the army as anti aircraft on bases and homeland safety. The guns could fire 160 rounds-per-minute, with an approximate effective range of 4000 yards. After the jet age came to be the guns were scraped due to they weren't able to keep up with the speed of jets. The 40mm Bofors is now placed on ac130 spectra gun ships, to be used against land based vehicles, and hardened bunkers.