Can you tell us more about the firearm you are shooting, the sight, and the ammunition? What you are describing sounds odd, so details please. Rule of thumb: move the rear sight in the direction you want the bullet to impact on the target.
it is a 45 cal green mnt barrel 1in 28 twist ,shooting the platinum power belts weight is 233 gr. started with 70 gr.of 3 f and when I didnt get results out of frustration went up to 90 gr...I am shooting about a foot low good center just low .I have the sight all the way up .I am shooting off of a bench with bags.at 40 yards it is good but at 70 yards no good
You need to lower your front sight. I had the same problem with my Lyman GPR and after several sessions with a file --ended up putting a turtle sight on the front end. Problem over. Lowering the front sight will bring the muzzle up.