It was commonly assumed by users in the service that the term referred to a supposed 'buzzing' sound its darts made when flying through the air. The first example was the 105mm howitzer M546 anti-personnel tracer (APERS-T), first fired in combat in 1966 and thereafter used extensively in the Vietnam War.
The term's meaning was commonly understood by users within the service to be a buzzing sound made by darts as they flew through the air. The M546 anti-personnel tracer (APERS-T) howitzer, first deployed in combat in 1966 and subsequently used extensively during the Vietnam War, is the first example of this term being used.