That was my concern also. They make a high weaver backup also. I almost got it. I'm glad I went with the low weaver backup, as it shoots about right with the aperture screwed all the way down. So I have quite a bit of adjustment . I think .05 changes POI 6 inches. Each 1/2 turn (180 degrees) is suppose to move poi 1 inch at 100 yards. there is 15 inches of adjustment on both windage and elevation.