Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The M242 Bushmaster is a 25 mm chain-fed autocannon. It is used extensively by the US armed forces, as well as by NATO''s and some other nations'' forces in ground vehicles and watercraft. It is an externally powered, chain driven, single-barrel weapon which may be fired in semi-automatic or automatic modes. It is fed by a metallic link belt and has dual-feed capability. The term "chain gun" derives from the use of a roller chain that drives the bolt back and forth. The gun can destroy lightly armored vehicles and aerial targets. It can also suppress enemy positions such as exposed troops, dug-in positions, and occupied built-up areas. The standard rate of fire is 200 rounds per minute. The weapon has an effective range of 3,000 meters, depending on the type of ammunition used. The weapon was designed and originally manufactured by McDonnell Douglas; however it is now produced by Alliant Techsystems of Mesa, Arizona.