With a 200-yard zero, the 100-yard POI was to the left and the 300-yard POI was to the right.
Over here with a pencil and paper desperately trying to figure out how this would be possible...
Could it be that the holes in the rail were off so the rail was not in alignment with the barrel? Think side-by-side double rifle - it's only regulated (common point of impact for the two barrels) for one distance if the barrels aren't perfectly parallel. Substitute a laser beam coming from the scope - at 200 yards, the bullet and laser beam would cross but before 200 yds the bullet would always be left of the beam, and then after 200 yds the bullet would continue past the beam so it was to the right of the beam for the rest of its flight.
