I just installed a dawson fiber optic on my trojan (little bit of a hack job i must admit:embarassed. I took it to the range today, and it seemed i was hitting about 1-2" low at 7 yards. I'm not sure if i was having an off day, or if the sights are causing me to shoot different than im used to. The dawson sight seems a bit taller than the stock one. Secondly, how the hell do you know when the sight is centered? I put it over the same mark as the old sight, but it might be a millimeter or two off center. Any advice on how to get it perfectly centered?