It’s a classic movie moment: Clint Eastwood as Dirty Harry points his handgun at a criminal. The gun may or may not be out of bullets.

“Being this is a .44 magnum, the most powerful handgun in the world, and would blow your head clean off, you’ve got to ask yourself one question: ‘Do I feel lucky?’ Well, do ya, punk?” he asks.

The scene might not be as effective if he were holding a slingshot, which seems more like a child’s toy a la Dennis the Menace. But research published Wednesday in National Geographic showed a slingshot used by the Romans some 1,900 years ago had nearly the same stopping power as a .44 magnum.

They used it in the opening attack of a war with the restive tribes living among the hills of Burnswark, Scotland. That war dragged on for nearly two decades. Eventually, the Romans retreated to a fortified barrier they had built known as Hadrian’s Wall.

Archaeologists John Reid and Andrew Nicholson began excavating the site five years ago, hoping to discover exactly what occurred at the battle. What they found was an astoundingly powerful, ancient killing device that rivals today’s weaponry.

Americans had previously learned about the Battle of Little Big Horn by using metal detectors to search for bullets, so the duo decided to do the same in Burnswark. They began finding small lead bullets, eventually discovering more than around 2,700 of them. They dug up 400 for examination.

The lead bullets were about 50 grams each. Strangely, about 10 percent of them contained small holes.

The confused researchers made copies of several bullets, both holed and solid, and gave it to a trained slinger.

The solid ones flew at up to 100 miles per hour and could hit objects smaller than a human 130 yards away. Furthermore, they contained the stopping power of a .44 magnum, that gun Dirty Harry carried around specifically because it was so powerful.

“The biggest sling stones are very powerful — they could literally take off the top of your head,” Reid told Scientific American.

They also solved the mystery of why some had holes. Those weren’t as effective as a weapon, but they produced “a weird banshee-like wail” as the wind whipped through and over the holes, Nicholson told National Geographic. The idea, he hypothesized, was to terrify the enemy with the noise during an attack, as a means of distracting them.

“So you are getting these unworldly, unnatural sounds that you have never heard before, and people are falling over on either side of you,” Nicholson said.

The location and number of the bullets found suggested a long, pounding siege on a hillside. It’s a tremendous thing to imagine, bullets raining down for hours while alien screams fill the air.

Comparative isotopic studies pit the battle around A.D. 140, around when Roman emperor Antoninus Pius took control of Rome and wanted to make a name for himself.

“He was a new emperor with a need for a military victory somewhere,” Reid said. Perhaps, he thought, Pius decided to lash out with an act of extraordinary violence to quickly conquer the tribes and display his prowess.

The Romans, of course, were known for innovation, particularly in their military. Theirs was the first civilization to include a military medical corps that performed surgery on wounded soldiers during battle. When waging a naval battle against the Carthaginians, the Romans invented the corvus, a sort of boarding ladder allowing their soldiers to clamber upon the enemy’s ships.

Perhaps the Romans most well-known military invention is Greek fire, otherwise known as “liquid fire.” What it was made from remains unknown, but it would burn on water. Greek and Arab soldiers reported that sand was required to extinguish it. A fictionalized version of it appeared on “Game of Thrones,” as the neon green “wildfire.”

Despite the Romans’ superior weaponry, however, the tribes better understood the uneven and often rough terrain. The battle dragged on, even as the Romans slaughtered whomever they met.  “We’re fairly sure that the natives on top of the hill weren’t allowed to survive,” Reid said.

Still, he added, eventually it began “to look like Rome’s Afghanistan.”

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