AGS-17
In 1960, the United States Army made the Mk.19, an Automatic Grenade Launcher that was used in the Vietnam War. It fired the powerful 40mm HE Grenade. It was proven effective in the war. The Soviet Union needed something to one-up this new design, so they made the AGS-17 with the help of Alexander Fedorovich Kornyakov and OKB-16 in 1968, but production would actually started in 1971. The Red Army tested the weapon in 1969, then started using it in 1971.