Actually he was using a 100 round SureFire stick mag. Not a drum. The picture of the rifle laying on the floor shows it.
Yup. Saw a bunch in a pic neatly stacked by one of the support posts in the room. Looked like around 10 or 12 which would be another 1,000 or 1,200 rounds he never fired. Surely he had them all loaded in advance. Wonder what sort of LULA he used to load those puppies up. Probably need to prohibit LULAs now too.