Originally Posted by Shiftie
You need to go back to the sniper mission once you unlock sniper rifles a mission or two later. Best spot to get it is to go a bit left of the starting point for the airplane hangar area and snipe down at the guys in and around the hangars. There's one dude off in the trees to the right, a 2 man patrol in front of you, guys in front of the hangars, guys in the hangars and one on the catwalk between them as well as guys in the towers in the back and a couple on the ground behind the hangars so make sure you can see as many guys as possible before you start firing, and I'd recommend going silent so they don't hide and force you to move.
le sigh, as i posted on another topic you DO NOT need to complete the mission and cmoe back with a sniper rifle. There is a weapon box in the left hangar that contains a sniper (i believe vss). And the best place to do this is at the end of the mission. Go to the rally point to start the ambush, then haul ass towards the tail of the plane. You'll see a large rock with trees scattered about. Stand behind there and you can take out enemies on the other side of the plane, as well as a shiz ton that will appear right in front of you