How the Las Vegas Shooter Could Have Gotten an Automatic Rifle

Anyone who has watched the sickening video clips of Sunday night’s Las Vegas mass shooting has heard the sound. It’s a staccato crackle of gunfire at a rhythm that almost resembles the cadence of a helicopter’s blades, far faster than a human being could repeatedly pull a trigger. That’s not the sound of the typical semi-automatic rifle owned by millions of Americans, but of an automatic one—or of a semi-automatic that’s been modified to be nearly as deadly.

The shooting at a country musical festival on the Las Vegas strip Sunday night has already become the most lethal in modern American history, with at least 58 people murdered and more than 500 injured by a gunman firing from a window of the Mandalay Bay Resort and the mu online Casino. But gun experts who have watched—and heard—recordings of that tragedy note another distinction: It appears to be the first mass shooting in decades to have been carried out with a weapon capable of firing at automatic, or near-automatic, speeds…