Killer had devices to make firearms fully automatic

The gunman who unleashed hundreds of rounds of gunfire on a crowd of concert-goers in Las Vegas had two “bumpstocks” that could have converted semi-automatic firearms into fully automatic ones, officials said.

The devices have attracted scrutiny in recent years from authorities. California Senator Dianne Feinstein has long railed against them. Several years ago, she said she was concerned about the emergence of new technology that could retrofit firearms to make them fully automatic.

“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,” she said.

A semi-automatic weapon requires one trigger pull for each round fired. With a fully automatic firearm, one trigger pull can unleash continuous rounds until the magazine is empty.

The purchasing of fully automatic weapons has been significantly restricted in the US since the 1930s.

In 1986, the federal National Firearms Act was amended further to prohibit the transfer or possession of machine guns by civilians, with an exception for those previously manufactured and registered.

Numerous attempts to design retrofits failed until recent years when bump stocks came on the market.

The device replaces the shoulder rest, with a “support step” that covers the trigger opening. By holding the pistol grip with one hand and pushing forward with the other, the shooter’s finger comes in contact with the trigger. The recoil causes the gun to buck back and forth.