>>515643457
There are some bolt action rifles that come apart or are "takedown" models. This doesn't look like one of them. They're generally regarded as pieces of shit with less accuracy, and they don't always hold zero when taken apart and put back together. Again though this doesn't look like a takedown model, and to put a traditional bolt action together you need tools like a press. Not doable on a roof.
You guys aren't thinking deeply enough into things, or maybe I'm just a master assassin. How'd he know the roof would be accessible? He had been up there before. He likely stashed the rifle. He's seen jumping off the roof with the rifle hanging out of his backpack and walks off with the barrel sticking out. He had it stashed prior and removed it after. I would've waited there all night under a blanket that matches the roof. Obviously that roof touches most of the campus, you don't really need to be picky with such a major obvious vantage point.