Imagine the riser isn't square as I diagram whenI was explaning 3rd axis adjustment and the laser ran out like the picture on the right,this is common,not to this degree but I hope you understand what I am trying to point out.
Blue represents the arrow.
The small rectangle that the sight runs off of is the riser.
Guess I should have labeled it.
link at bottom
Here is the link because you missed it because you were off wasiting time chasing elk or something like that.

http://www.huntingnet.com/forum/tm.aspx?m=2282390