Just so everyone knows, you can actually use your scope on regular rifles and smg's etc. A lot of people just assume the scopes only give you a stat boost, but if you're a true gamer then you'll know that they don't give you an actual scope on the weapon if you can't really use it. Using keyboard, pull your weapon out that you want to use (that has a scope on it). Go into first person camera mode and hold right click so you are aiming....WHILE YOU ARE AIMING, MOUSE SCROLL WHEEL UP and it will take you to the RDS scoped in.
Every forum I have seen says you can't use scopes blah blah, they don't take the time to actually investigate the situation. Also, they all lock their threads before a real gamer can actually post the TRUTH for them. Anyways, I do not know what the CONTROLLER commands are but that's only bc im not a filthy casual, Keyboard/mouse is the ONLY way to play PC games (unless its a racing game). Anyways, hope this helps at least some of you out there.