Military terminology
Gun – Most soldiers and marines carry rifles and in military terminology a rifle is not a gun. A pistol is a gun and a machine gun is a gun. Confusingly, in civilian terminology a rifle is a gun. The movies and television are usually responsible for getting this wrong. An exception is the 21-gun salute. Historically, when a ship entered port it fired all its cannons (called guns in navy-speak) emptying them to show it was friendly.