M6 Series Helicopter Armament Subsystems Twin (2pcs) Ammunition Chute Assy On UH-1B/C

Although one of the first armies to experiment with helicopters, the United States Army was slow to fully explore the possibilities of armed helicopters. Experiments between the Korean War and US involvement in South East Asia were small and fairly simple. Learning much from these involvements the US decided to look further into the idea of air mobile tactics, and subsequently armed helicopters, though an armed helicopter had been proposed and rejected in the early 1940s. By the time the UTTHCO (Utility Tactical Transport Helicopter Company) was deployed to Vietnam in 1962, the US had started experimenting more with the idea of arming helicopters both for defensive and offensive purposes.[1] UTTHCO was an expeditionary unit, deployed to Vietnam to assist the South Vietnamese Army and to provide on the ground testing for new air mobile theory. Weapon systems used by UTTHCO were often crude and made from field expedient parts and weapons. 

By 1965, the United States had deployed a truly Air Mobile unit, the 1/7th Cavalry, which began to use more standardized armament systems. Throughout US involvement in Vietnam the US Army, US Marine Corps, and US Air Force would develop and utilize a number of armament systems designed for a variety of helicopters, and would pave the way for more dedicated attack helicopters. 

With the arrival of dedicated gunship helicopters such as the AH-1 Cobra and later the AH-64 Apache, armament subsystems for non-specific types would begin to drop off, with mostly defensive armament packages remaining. Such armament packages, giving decidedly heavy armament to small or primarily transport helicopters, have become popular among second and third world countries who lack the funds for dedicated attack helicopters. Most of the systems bear some resemblance to the plethora of US systems that follow in this entry.