Problem is, the game can't portray the bouncing and shaking in the model of you actually running. Instead, this is portrayed by the crosshairs. Just as well, You normally can't fire a rifle when running, because its incredibly uncomfortable to hold a rifle the way it is in non-iron sights ingame for very long. Normally, when running, the rifle is held with one hand in the middle near the leg, across your chest, or over a shoulder.