brass count?

The brass was grabbed as souvenirs. People walking around Mandalay Bay looking up at that 32nd window from which Stephen Paddock had gunned down concert goers were prone to pick up the brass shell casings which came from Paddock's machine guns. Such souvenir-taking might explain "why" there is so little brass found not only in Paddock's hotel room...but also...on the ground outside his 32nd window.