The Hispano Sound from the WW2 Weapon SFX sound library is the sound of an 20mm autocannon. It was originally designed and produced by French company Hispano-Suiza in the mid-1930s. During World War II French, British, American, and numerous other military services used it as an aircraft, naval, and land-based weapon. For example, in this library you can find the sounds of two Hispano Mk II cannons for Spitfire.
It consists of the looped audio file 9 seconds long and the ending file, which should be played at the end of the shooting. The WW2 Weapons SFX Library library includes 28 audio files.