The shoulder fired Soviet RPG-7 antitank grenade launcher was supplied in large qualities to NVA and VC troops during the Vietnam War and was particularly effective at shooting down U.S. helicopters. It featured a 40mm diameter barrel; weighed 19 pounds when loaded and had an effective range of 500m. The 85mm grenade (PG-7) was ejected from the launcher at 117 meters per second by a small powder charge. After travelling approximately 11 meters a sustainer rocket ignited that boosted the grenade to a maximum speed of 294 meters per second.1 To improve accuracy it also featured 4 spring-loaded stabilizer fins that only opened up after the grenade had been propelled out of the barrel.
1. TRADOC Bulletin 3. Soviet RPG-7 Antitank Grenade Launcher. (United States Army Training And Doctrine Command November 1976)