Re: Reticle not parallel with knobs, normal?
I have done parallel spacing with the feeler guages (and still do it on all rifles that I don't have a USO anti-cant level on), but after taking a close look at my USO anti-cant, I'm not so sure it snugs the level down perfectly parallel with the rail.
If you'll notice what you quoted of mine, I do not trust the cap and O-ring, I remove caps and the turret on USO's and level the actual erector mech to my rail level-as that's what I check when I fire.
Not having experience with Falcon's personally I didn't recommend the feeler guages as I don't know what the bottom of their erector housings are like and if their erectors are even plumb to the housings.
In the absence of a anti-cant level I heartily agree with the feeler guage method.
After all that typing, I really have come to the conclusion that the best advice to give the original poster is the old school method:
-Fix rifle in a rest so that the rail is level.
-Without disturbing the level of the rifle, affix scope so that the vertical component of the reticle is plumb against a plumb bob (weight on string) at a distance you can see in scope.
-while watching said plumb bob through scope crank the elevation knob. If the crosshairs veer waya from the plumbline your reticle is canted in relation to your scope's erector and you will have problems at distance.