I have seen pictures here and on other sites that show some glocks with Dr. Optics Red Dot Sight Mounted to the top of the slide. But its not mounted to the slide via the dovetail its sunk into the gun. They Cut away material in the top back section of the slide and monted the sight down low ( I think it was on a Glock model 21). I have not been able to fnd these pictures again or the post on the website so I could ask the people who did the cutting? How is the sight mounted into that cut-away area? How hard was it to mount it. What holds the sight into the cut-away? Generally why and how does it work?? I guess it lowers the sight plane closer to the barrel for more accurracy. Any info would be helpful.