Splashes water on the floor to keep dust down from the muzzle gasses, uses a separate scope to take measurements from a second location, uses a shroud over the scope to break up the silhouette while shooting, and I guarantee that barrett scope has a piece of nylon over the front lens to prevent sunlight glinting off the scope down range. So if they do catch a glimpse while he flashes the standalone scope to get measurements, once he fires they return fire at the wrong window.