A closer look at bump stocks the new target in U.S. gun control debate

Semi-automaticweapons used by the Las Vegas shooterwere reportedly equipped with bump stocks devices that can increase the rate of fire to something similar to that of fullyautomatic weaponsand have quickly become the focus of the gun control debate.

The devastating carnage that left 58 people dead and more than 500 injured has some pro-gun Republicans and even the powerful National Rifle Association talking about the need to review the legality of bump stocks and create new regulations.

But there is some debate among gun experts about whethera gun equipped with a bump stock actually becomes a more lethal weapon.

Perched nearly 100 metres above ground on the32ndfloor oftheMandalayBay hotel about 350 metres from where an outdoor country music festival was taking place Sunday night, Stephen Paddock rained down gunfire on the crowd of festivalgoers through a broken window.

According to officials, 12of Paddock's semi-automatic rifles were fitted with bump stocks.

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For semi-automatic gunsnot fitted with bump stocks, the user must deliberately pull the trigger each time to fire off a round.Fully automatic weapons allow an individualto pull the trigger back and continually shoot until the magazine has emptied, meaning the rate of fire is substantially faster.

But fully automatic weapons are severely restricted in the U.S. New fully automatic weapons are only manufactured for law enforcement officials and the military. Civilianscan only purchase onemade before 1986and must undergo extensive background checks and be prepared to pay a steep price.

Many older machine-guns sellfor around $15,000 US but can range in price from $30,000 to $40,000.

Substantially faster

It's illegal to drill holes and install parts into semi-automatic weapons in an attempt to make a weapon fully automatic. This is why somegun enthusiasts will opt for a bump stock device, a legal alternative that can simulate rapid firing.

"It simulates something that everybody wants to try but nobody can afford," said Brian Guerra, co-owner of the Texas-based Armas De Guerra LLC, a gun manufacturing company.

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A bump stockcosts around $250 and replaces the gun's shoulder rest, with a "support step" that covers the trigger opening.

When firing a gun with a bump stock, byholding the pistol grip with one hand and pushing forward on the barrel with the other, therecoil of the gun pushes the gun back and forth so that the shooter'sfinger re-engages, or "bumps," the trigger faster, increasingthe number of times one can pull the trigger.

VIDEO: How a bump stock works

7 years ago

Duration 0:40

CBC News explains the mechanics behind the bump stock rifle attachment

In 2010,Slide Fire, a gun manufacturer that makesthe bump stock device,asked the the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF)to evaluate the admissibility of its new mechanism. The agency approved the device.

But critics of the bump stocksee it as a loophole in the law thatallowsgun users to own weapons that have been effectively transformed into fully automatic machine-guns.

'Pretty damn close'

Senator DianneFeinstein, who has called for a ban of the device,said bump stocksincrease a semi-automatic rifle's rate of fire from between 45 and60 rounds per minute to between 400 and 800 rounds per minute.

The only reason to modify a gun is to kill as many people as possible in as short as time as possible.- DianneFeinstein, Democratic senator

"That's the same rate of fire as automatic weapons," the Democrat told reporters on Wednesday. "The only reason to modify a gun is to kill as many people as possible in as short as time as possible."

FrankieMcRae, a former Green Beretwho currently trainsspecial operation forces for the U.S. Department of Defence, said he doesn't deny that you can shoot faster with such a device.

"When we're talking semantics of full auto versus bump fire, and we're getting the same effect, you're getting pretty damn close to that," McRae said.

However, bump fire guns or fully automatic weaponsare just not asaccurate orreliable as semi-automatic rifles, he said.

"The bump fire is actually not a very accurate attachment tothe rifle, because you're kind of all over theplace with itbecause of the way you have tohold it, so the gun has to move a lot more."

'Don't need to be accurate'

In fact, he said Paddock would likely havekilled more peoplehad he used a semi-automatic weaponthat had not been modified withthe bump stock.

"He could have actually been moredeadly witha semi-auto rifleand accurately able to aim and take shotsthan with a bump fire,"McRaesaid.

Retired ATF agent and Iraq war veteran Hector Tarangoagreed that semi-automatic weapons with bump stocksare less accurate, but he said that certainly didn't make Paddock's horrific attack any less deadly.

"You don't need to be accurate when you're shooting into 1,000 people or more."

In the Las Vegas shooting, where 22,000 were crowded together in an enclosure,the shooter's gunfire forced people to flee through a small openingin the fencing that surrounded thefestival grounds, making them much easier targets.

"They're not going anywhere, so he doesn't have to be good. Every shot that he fired, he was hitting someone. He's just spraying."