Also remember that a scope's reticle subtends twice as much area at 200 yards as at 100, making precise aiming more difficult. Scope parallax may also figure into the equation as well. Personally, compared to the group at 125 yards, that 200 yard group doesn't look all that awry. Maybe you could do a little impromptu test of the parallax by fixing the rifle in the rest and moving your eye side to side in the eyebox to get an idea of how parallax might be affecting you at both ranges.
