Tribal warriors who faced an opposing Roman army in battle almost 2,000 years ago were stricken down by a hail of bullets as powerful as those in a modern handgun.

That is the finding of research which analysed slingshot ammunition found at an archaeological site last summer.

The stones, which h urtled along at up to 100mph (160km/h), could take the top of your head off with nearly as much force as a .44 Magnum.

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German researcher and slingshot enthusiast Jörg Sprave has analysed the kinetic energy of ancient slingshot bullets found in Scotland (pictured) to make the startling discovery about their stopping power

ANCIENT BULLETS In the second century AD, the Romans used slings to launch the bullets, which were drilled to produce a buzzing sound compared to an agitated wasp. Archaeologists believe they were an early form of psychological warfare employed by the Romans. And they would have proved a deadly weapon against the Scottish clansmen who faced them with swords and other simple armaments. A collection of over 400 of the bullets were discovered by the Trimontium Trust, a Scottish archaeological society, at Burnswark Hill located just west of Dumfries, last June. And German researcher and slingshot enthusiast Jörg Sprave has since analysed their kinetic energy to make the startling discovery that they would have had the same stopping power as a modern .44 Magnum handgun. Advertisement

In the second century AD, the Romans used slings to launch the bullets, which were drilled to produce a buzzing sound compared to an agitated wasp.

Archaeologists originally thought the holes were to hold poison, but discovered they were an early form of psychological warfare employed by the Romans, creating a sound designed to intimidate their enemies.

And they would have proved a deadly weapon against the Scottish clansmen who faced them with swords and other simple armaments.

A collection of over 400 of the bullets was discovered by the Trimontium Trust, a Scottish archaeological society, at Burnswark Hill located just west of Dumfries, last June.

And German researcher and slingshot enthusiast Jörg Sprave has since analysed their kinetic energy to make the startling discovery.

He believes they would have had the same stopping power as a modern .44 Magnum handgun, which fires bullets at speeds of around 1,475 feet per second (450 metres per second) and imparts 1,160 foot-pound force (1,570 joules) of energy.

Speaking to National Geographic John Reid, chairman of the Trust, said: 'We’re fairly sure that the natives on top of the hill weren’t allowed to survive.

'This is beginning to look like Rome’s Afghanistan.'

The hill where the whistling bullets were discovered was the site of an assault by Roman legions against native tribes people.

Weighing about one ounce (30 grams), each of the bullets had been drilled with a 0.2-inch (five millimetre) hole.

A collection of over 400 of the bullets (pictured) were discovered by the Trimontium Trust, a Scottish archaeological society, at Burnswark Hill located just west of Dumfries, last June

A German researcher believes the bullets would have had the same stopping power as a Magnum 44 handgun (pictured), which fires bullets at speeds of 1,475 feet per second (450 metres per second) and imparts 1,160 foot-pound force (1,570 joules) of energy (stock image)

Dr Reid believes the holes converted the bullets into a 'terror weapon.'

Speaking at the time of the discovery, he told LiveScience: 'You don't just have these silent but deadly bullets flying over; you've got a sound effect coming off them that would keep the defenders' heads down.

'Every army likes an edge over its opponents, so this was an ingenious edge on the permutation of sling bullets.'

The noise was a kind of buzzing which sounds like an 'agitated wasp' according to Dr Reid.

The idea of terrorising enemies using weapons that make a horrific noise was more recently adopted by the Nazis in World War II.

Weighing about 1 ounce (30 grams), each of the bullets had been drilled with a 0.2-inch (5 millimeters) hole, which created a noise as the bullets travelled through the air

This left image shows a replica Roman Scorpio crossbow, one type of small artillery weapon used by Roman forces. Among the finds was ammunition from Roman artillery weapons, such as this stone ball (right) which may have been fired from a ballista

The bullets were found on Burnswark Hill is located west of Dumfries in Scotland, shown on map. It was possibly the site of a siege during the early conquest of Scotland

HOW DID THE SLING BULLETS WHISTLE? Together with arrows and catapults, sling-shots formed a key part of the long-range fire of the Roman army. Lead bullets were cast in the shape of lemons or 'acorns', which would weigh around 1.7 ounces (50g). Weighing around 0.7 ounces (20g), the holes were around a fifth of an inch (5mm) wide and the same deep. While the size of these bullets would have made them not terribly dangerous, experiments using replicas of these small bullets showed that they produced a whistling noise while in flight. It is thought the sound is produced by the air moving over the small opening, much like when blowing over the top of a milk bottle. This has led some theories that these smaller bullets were used to invoke terror in the enemy. It is a tactic that has been used by military forces around the world. Mongolian archers were said to have used whistling arrows before they were later adopted by the Chinese and later the Japanese Samurai. The Nazis used whistling weapons to great effect during the Second World War, fitting Stuka bombers with sirens to strike fear into the enemy as they dive bombed. The V1 Flying bomb also produced a distinct buzzing noise that could be heard from miles away. When the noise stopped, it signalled the weapon was dropping to the ground. Advertisement

The Junkers Ju 87 or Stuka was a German dive bomber and ground-attack aircraft which first flew in 1935 and had unmistakable wailing sirens.

According to Dr Reid, the bullets could be fired in groups of three or four, creating a slingshot effect.

About 20 per cent of the lead sling bullets found at Burnswark Hill had been drilled with holes.

This was a significant amount of effort to prepare enough ammunition for an assault, Dr Reid said. 'It's a tremendous amount of work to do, to just chuck them away.'

'Even more intriguingly, the mysterious holes proved to confer an aerophonic quality,' Dr Reid said in Current Archaeology.

'In flight, these lead shot whistled, or more accurately gave off a mechanical buzzing sound eerily reminiscent of an agitated wasp.'

Rising nearly 1,000 feet from the rolling countryside around it, Burnswark Hill in Dumfriesshire were an imposing defensive position. The fort and the camps date from around the time when the Roman emperor Antonius Pius ordered the reconquest of Scotland during the 140s AD

Burnswark Hill (pictured) in the Dumfreisshire region of south-western Scotland is thought to have been the site of an assault by Roman legions in the second Century AD against native tribespeople defending the hilltop fort

The Trimontium Trust is directing a year-long archaeological investigation of Burnswark Hill. At the time of the Roman attack on Burnswark Hill, slings were used mainly by specialized units of auxiliary troops who had been recruited to fight alongside the Roman legions

At the time of the Roman attack on Burnswark Hill, slings were used mainly by specialised units of auxiliary troops who had been recruited to fight alongside the Roman legions, according to Dr Reid.

The most feared slingers came from the Balearic Islands.

They had fought for the Roman general Julius Caesar in his invasions of Britain in 55 BC and 54 BC.

'These guys were expert slingers; they'd been doing this the whole of their lives,' Dr Reid said.

A heavy sling bullet or stone could reach speeds of up to 100 mph (160 km/h) in the right hands.

WAS BURNSWARK THE SITE OF A BATTLE OR A TRAINING CAMP? Rising nearly 1,000 feet from the rolling countryside around it, Burnswark Hill in Dumfriesshire were an imposing defensive position. Archaeologists have found evidence for an Iron Age hill fort and settlement that crowned the top of the lumpy formation, which lies just ten miles north of Hadrian's Wall. Either side of the fort are the remains of what appear to be two Roman camps – one to the north and one to the south. Historians have argued over this unusual configuration of Roman military camps on either side of the hill fort since it was first discovered in 1785. The earliest interpretations claimed that it was the site of a siege as the Roman army attempted to capture the imposing fort. The fort and the camps are thought to date from around a time when the Roman emperor Antonius Pius ordered the reconquest of Scotland during the 140sAD. However, in 1964, further excavations led to the suggestion that the fort had been abandoned by the second century AD when the Roman army is thought to have set up the camps. This has led to the theory that the hill fort was actually being used as a training site for the Romans, partly due to the unusual shape of the camps. They were unlike any other Roman military camp – rather than having a centrally placed entrance on each side of the square camp, the North camp had a smaller rectangular square tacked onto the side. The presence of 'obsolete' acorn shaped lead sling bullets has also led to claims that the site was used for training rather than a real battle. However, others have pointed to the scatter of sling bullets around the site and say they match what would be expected from a besieging attack rather than target practice. Advertisement

'We undertook a ballistic assessment of the lead sling-bullets previously found on the site in order to assess the performance of this ammunition,' Dr Reid said.

The group made replica bullets cast in lead and high-density clay and used a volunteer to weave slings from various materials.

'We found that the larger 1.7 ounce (50g) bullets could be cast at least 656ft (200 metres) depending on whether the low-trajectory direct (more accurate) or lob style (greater distance) of slinging was used.'

The Trimontium Trust is directing a year-long archaeological investigation of Burnswark Hill.