My G22 needed the rear drifted way to the right. I removed the slide, never drifting sights with slide on the frame. I have plastic drifts. Someone holding the slide on a padded bench, (assuming you have no vice), holding the punch at an angle so the base of sight is contacted moreso than the top part, start tapping lightly, then increasing force till you see movement. It may "overshoot" and you will have to go the other way, of course. If you have night sights, be careful not to hit anywhere but the base. At least those factory Glock sights are cheap if you mess up. Have someone else try your G-17, as you may be pulling the shots left...its possible, I did it too at first, getting to know the Glock.