Southpawshooter is right, if you have some 100gr laying around try them, and see if they make a difference. At that length the difference may be slight but noticeable.
Just from past experiences, don't get hung up on how the knock end of the shaft looks unless its severe. If its shooting where your aiming at 20 yards, and shooting consitently, the appearance of the knock kicking left or right will go away with the stabilizing effects of the fletchings. If the arrows were striking up or down or to the left or right of my point of aim, then I'd concern myself more with spine.