I picked up a pristine (unissued) LE trade-in G22 a while ago and decided to replace the dim night sights on it with standard sights. Rear sight was easy as usual, but the front sight is connected with what looks like an oval rivet from below the sight (looking inside the slide). I gave it a couple of whacks with a brass punch to see if it would pop out. Bent the punch the and sight did not budge. Any tips on removing this without damaging the slide? Can u give me more info?