It is called "M242 Bushmaster Automatic Cannon" it is 25mm and can fire at three rates. Single, 100rds per min and 200 rds per min. It can use three types of ammo. TPT-training practice tracer, HE-high explosive, APDS-armor piercing discarding sabot. max range is out to 3000 meters. (if i remember right). It is also called a "chain gun" as the bolt rides along a chain path that allows the high rate of fire. At the time i used this weapon, it was made by Hughes Helicopter. I loved shooting it. The barral weighes in at 90lbs the upper reciver is 90lbs and the lower was over a 100 lbs. This gun is alos used on the USMC LAV-25. Great stuff, great weapon system.
Bradley Gunners do it with Chains~
CB