Also, unless you are roleplaying an asshole, there is no reason to do a lethal takedown, ever. Contrary to what the tutorial implies, you don't have to sneak up on someone to do a takedown.However, if you have the director's cut, an actual sniper rifle can be found early on. In my previous hint I recommended choosing the tranq rifle from Sarif, because it's the only scoped long-range weapon you get for a while.
It's the only scoped weapon you'll get for a while.