Well i just got this SWFA SS 20x42 scope and i installed on kalinka low BP-02 side mount with Burris XTR 30mm rings .50 height. Problem is brass is hitting windage knob badly from underneath. Its eaither case mouth or rim because marks are straignt and narrow.
I was thinking installing set screw mod on gas block but im not sure is this gonna help
Here is short video from range today. No its not slowmo video

http://youtu.be/CvUK4Mh9Tw0

Here is some pics

I would rig up some sort of deflector personally, instead of messing with the scope.

I have a bolt gun that does the same thing.  Being a bolt gun, it doesn't do it with the same enthusiasm that a semi-auto does, but it still dings the turret up pretty well.



I put a rubber cap (got it from work) over the end of the turret where the shell casings were hitting and that was the end of that.