sight adjustment on Ruger Blackhawk: I have a 357/9mm convertible ruger blackhawk. at 7 yards the shot group was low until I raised the rear sight as far as it would go. It was so high that the discharge caused the screw to completely come out of its hole and the sight sprang up off its base. I have always wondered why the front sight on rugers is so big. It makes it impossible to align the sight line with the barrel line. What am I doing wrong? I align the top of the front sight with the top of the rear sight when firing, as the instructions say to do. Has anyone else had this problem? and if so how to solve it. Thanks!