I just got my Glock 19 slide back from AETI Guns. The mill work is perfect with the RMR sight custom fit to the slide. There is no gap between the slide and RMR and has bosses machined to take the recoil. Excellent job By ATEI Guns. I would highly recommend them. The RMR co witnesses with the front sight post perfectly, my photo doesn't show this at all. I was using my potato phone and was struggling to get a good photo.