Mounting them forward makes no difference, they still work perfectly. For me mounting a red dot on the receiver of my CZ550 in 505 or 416 positions the sight way to high as both stocks are setup for open sights, therefore mounting a red dot where the rear sight base sits positions the dot at the correct height using a Burris FF4. I have designed a rear sight base that allows a FF4 to be mounted with a QD mount but still has a single standing leaf. A quick flick of a lever removes the red dot and the open sights can be used. I have 3D printed one in plastic and tried it and the position of the dot is perfect for the stock and very easy to use. Now I just have to make one in steel if I can ever get onto my own machines rather than customers jobs lol.

Matt.