DUMFRIESSHIRE, SCOTLAND—Cast-lead sling bullets recently unearthed in southwestern Scotland are thought to have been used by Roman auxiliary troops during an attack of a fort on Burnswark Hill some 1,800 years ago. Such sling bullets range in size from an acorn to a lemon. About 20 percent of the sling bullets recovered from the site had been drilled with a small hole. Similar sling bullets have been found at ancient battle sites in Greece, and at first, researchers thought the small holes might have contained poison. Now archaeologist John Reid of the Trimontium Trust thinks the projectiles with holes might have produced a whistling sound intended to terrify opponents, since his brother pointed out that lead weights used for casting fishing lines can produce a whistle in flight. “We think it was an all-out assault on the hilltop, to demonstrate to the natives what would happen to them if they resisted,” Reid said in a Live Science report. His team thinks the small bullets, shot in groups of three or four from a pouch attached to two long cords, were used for close-range fighting. For more on archaeology in Scotland, go to "Neolithic Europe's Remote Heart."