A “bump stock” modified AR-15.

Now appears that reports of automatic fire by Las Vegas mass murderer Stephen Paddock confused the rapid fire of a bump-stock modification on an legally modified AR-15 allowed rapid fire, along with 60-100 count magazines, to pump more lead into the crowd and accounted for at least 59 dead and more than 500 wounded.

Federal gun authorities say Paddock legally acquired the collection of more than 20 pistols and rifles assembled by Paddock in his hotel suite in the Mandalay Resort and Casino.  Even the bump stock, which allow recoil to simulate rapid fire of a weapon, is legal.

Adds Washington Post writers Devlin Barrett and Alex Horton:

Modifications such as the bump stock and crank do not technically qualify adapted rifles as automatic weapons or machine guns, which are legal but difficult to obtain and highly regulated in the United States. Those weapons are commonly found at gun shows and firing ranges, including one near Las Vegas that allows customers to shoot military-grade weapons.

The high number of firearms found at the hotel suggest a concern for overheating rifle barrels. The barrels can reach several hundred degrees, turning orange and even blue as rounds travel thousands of feet per second through them. In one crime-scene photo published by the Daily Mail, the gunman appears to be wearing a glove on his left hand, probably for holding a smoking-hot barrel.

What no one seems to know yet is what caused a retired millionaire accountant like Paddock go on a murderous assault.

His girlfriend returned from the Philippines and Wednesday and authorities hoped she might be able to provide a clue as to what drove him to commit the atrocious act.

Marilous Danley, the girlfriend, offered little help saying, through her attorney:

I knew Stephen Paddock as a kind, caring, quiet man. He never said anything to me or took any action that I was aware of that I understood in any way to be a warning that something horrible like this was going to happen.

A horrid story that is still developing…