South Korea is buying 82 U.S. 20mm automatic gun systems for the A-50 (the attack version of its T-50 jet trainer). The three barrel rotating barrel 20mm gun carries 204 rounds and can fire them at the rate of up to 3,000 rounds per minute. That provides the pilot with about four seconds worth of fire. The system experiences one jam every 9,000 rounds fired. The system weighs 300 pounds and the current model has been in service since 2004. The A-50 is a 13 ton aircraft that is basically an armed version of the T-50 supersonic jet trainer. The T-50 was designed to service as both a trainer and a combat aircraft. Deliveries of the 20mm gun systems will begin next year.