Robert Dilger's life revolves around the machinery of war. A former fighter pilot who flew combat missions in Viet Nam, he had persuaded the Air Force to adapt a 30-mm Gatling antitank cannon to its A-10 Thunderbolt close air- support aircraft.
After retiring from the military in 1980, Dilger, now 54, became a part-time consultant to Oregon Republican Congressman Denny Smith, during which time he tried to interest the Pentagon in a similar, single-barrel antitank gun -- this one homemade. Last week his project misfired.
Dilger's 8-ft. cannon was in the back of his Dodge pickup truck when he pulled into...