You may find it helpful to add an arrow rest, to lift the arrow above the shelf about the same amount that you will need to raise the nocking point on the string. My three under buddy had a time tuning his new bow, an arrow rest made all of the difference, eliminated the porpoising. On his I offered a Pararest, his arrow is about 1/8" above parallel from the top of the brush with the rest about 5/16" above the shelf. He shoots a recurve with a straight sided sight window, a long bow with a diminishing sight window would cause a less center shot situation with an elevated arrow rest.