a pellet movement of .05 inches, barely perceptible. Your scope has 1/8 MOA per click adjustment or 8 clicks = 1 inch at 100 yds or .10 inches at 10 yds. I would set it to be dead on the 55 yd target and forget everything else.
Scott's point about cant is also very applicable. Also have you trued your scope rings?
Jim in Sacramento