Last week I got set of competition kit sights for HK P30L, made by Dawson Precisions. Sights are with fiber optic front and plain rear sight. I followed great intruction on installing sight from Dave Dawson on his You Tube channel and had (almost) zero problem installing sights. Those instructions can be found here: rear sights and front sights.
Then I went to the range to confirm zero on new sights. I was shooting off hand 10 shot groups on distances (left to right target) 10m, 15m and 25m. Those are not best groups I ever made. It was my "trigger jerking" day apparently. I promise to try harder next time.