The M242 Bushmaster is a 25mm autocannon, used on a variety of ground, air, and sea vehicles. It can engage personnel, lightly armored vehicles, fast-moving vehicles such as speedboats and helicopters, and buildings. Multiple kinds of ammunition are available, and, when the mounting allows it, as in the M2 Bradley armored fighting vehicle, the gunner can change to the type most appropriate to the target.
No specific fire control system is part of the gun. On helicopters and in land combat vehicle, there is usually some type of electro-optical viewing system, in the visible light or infrared light spectra, for aiming the gun, but that is more a facet of the platform carrying the gun than of the gun itself.
Mechanically, it is an electrically powered chain gun, which allows the gunner, depending on weapons controller program, to fire single shots, short bursts, or long bursts. Bradley gunners engaging enemy armored vehicles, for example, would usually fire a single ranging shot, and then a burst of three rounds to destroy the target. Especially when firing armor-piercing ammunition, the weapon is surprisingly effective against hard targets; it will not defeat the frontal armor of a modern tank, but it demonstrated the ability to kill older tanks such as the former Soviet T-54 or T-62 tank.
The Mark 38 Bushmaster II is a 30mm derivative of the M242, used on United States Navy ships and Norwegian land combat vehicles.