I can think of any number of ways.So he could have made 60 kill shots and several hundred wounded in 30 seconds without a bump stock?
He had $30-40k of firearms in the room - more than enough to buy a water-cooled M1919 and 10,000rds of .30-06.
Oh - and a hose to run water to and from the bathroom.
Casualties would have been an order of magnitude higher.