Switch your rifle to Three-Shot-Burst mode, increasing your effective range and firing three 220-damage shots every 0.4s.
Reduce the Cooldown of Frag Grenade by 1-5s for each enemy hit by it.
Increase your maximum Health by 50-250.
Increase your Movement Speed by 10-50% while using Iron Sights.
Gain 8-40% Lifesteal while using Iron Sights.
Reduce the time it takes to bring up Iron Sights by 15-75%.