Definitions for "120 mm M1 gun"
The 120 mm Gun M1 was the US Army's standard super-heavy anti-aircraft gun, complementing the smaller and more mobile 90 mm M3 in service. Its maximum altitude was about 60,000 ft, which garnered it the nickname the stratosphere gun. 120's served primarily in US defensive roles, although it had been designed to be mobile and saw some action during the Korean War. The 120 was phased out quite quickly in the 1950s with the introduction of the first truly effective missile systems, notably the Nike Ajax.