I have a left-handed Stag upper and I just bought a LaRue Tactical Cantilever CompM Aimpoint Mount for my CompML2. I realized that having the mount on the rail keeps my ejection port cover from opening all the way. It's at least at a 90 degree angle from the opening, but I'm wondering if this will cause a problem for extracted brass. I know I could always remove the cover, but I was curious if anyone knows the angle that extracted brass leaves the port? I don't have a camera on me, but if anyone has the mount just throw it on the reverse direction and you should see what I'm talking about. Thanks in advance!

You should be fine. Most of the time the brass will come straight back and hit the deflector.