http://time.com/4965932/las-vegas-shooting-gun/
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Popular Mechanics: Vegas Shooter Had 'Bump Stocks' To Convert Rifles to Full-Auto
The gunman who opened fire on an outdoor concert in Las Vegas had two "bump-stocks" that would have allowed a semi-automatic gun to shoot more like an automatic weapon, the Associated Press reports.
The devices replace the gun's shoulder rest with a "support step" that covers the trigger opening, using the recoil from the gun's firing to bump the user's finger to "bump" the trigger, allowing it to fire at a faster rate. If bump stocks were used, they would allow Stephen Paddock to fire hundreds of times into the crowd at the at the Route 91 Harvest Festival at the Mandalay Bay in Las Vegas on Sunday night.
California Democratic Sen. Dianne Feinstein has long criticized bump stocks, arguing that they essentially retrofit semiautomatic weapons, which are legal, to make them fully automatic weapons, which are not.
Automatic weapons manufactured and registered with the government before 1986 can still be legally bought, owned and sold. To buy one, you need to submit fingerprints and photographs to the Bureau of Alcohol, Tobacco, Firearms and Explosives, submit to an FBI criminal background check and pay a $200 tax, among other restrictions.
Can you convert a semiautomatic to be more like an automatic weapon?
Yes, easily, cheaply and legally. There are a couple types of devices anyone can buy that modify a semiautomatic weapon to function more like an automatic weapon with burst fire, USA Today reports. A ”trigger crank" or ”gat crank" attaches onto the trigger guard, and the shooter then rotates the crank, which will the pull the trigger about 3x per rotation. A ”bump stock," also legal in the U.S., adjusts the stock of the gun so that the recoil itself fires rounds in rapid succession. Both devices are sold online in the neighborhood of about $50 to more than $100. You can't modify the internal components of the gun to make it fully automatic, but these workaround accessories are perfectly legal.
Found this browsing through the Time site.
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Popular Mechanics: Vegas Shooter Had 'Bump Stocks' To Convert Rifles to Full-Auto
Bump stocks are simple pieces of equipment that replace the stock of a rifle and add a small "support step" in front of the trigger. The shooter rests his finger on this step and pulls forward on the barrel or forward grip to press the trigger against his finger. The recoil of the shot then propels the rifle backwards into a gap in stationary stock where the loose fit gives the rifle freedom to bounce forward. This, along with sustained forward pressure on the rifle, has the effect of 'bumping' the trigger back into the shooter's unmoving finger. So long as a shooter maintains forward pressure, the rifle will continue to fire at a rate much faster than could be accomplished with even the quickest possible series of manual trigger pulls.
Two of the main manufacturers of bump stocks —Bump Fire Systems and Slide Fire—have posted letters from the Federal Bureau of Alcohol, Tobacco, Firearms, and Explosives, which declare these devices as legal in large part because they "[have] no automatically functioning mechanical parts or springs and [perform] no automatic function when installed."
They do, however, have the practical effect of drastically increasing rate of fire. As California Sen. Dianne Feinstein told the AP, "This replacement shoulder stock turns a semi-automatic rifle into a weapon that can fire at a rate of 400 to 800 rounds per minute."
Officials are still investigating whether the two bump stocks found in the room were actually used along with the rifles during the massacre.