Yes a two point sling is what you need, but you could possibly run a one point sling with the proper adapter either in front or behind your iron sights.
Two Points (Don't cheap out on two points, get a good one.)
One Points (If you get the one point I highly suggest any bungee sling, love em)
Adapter for One Pointshttp://www.airsoftgi.com/product_info.p ... ts_id=7608