Just received my first issue of "Shotgun Sports" an outstanding magazine. Anyway, in it is an article on "SHOTGUN FIT". I pick up my Beretta 686 and WHAT? My beads don't line up! They are strait on the rib but what I see is the rear off center to the left of the front and slightly down. I am now to led to believe I need an adjustable comb for 4 directions ( up, down, left, right). I'm O.K. with that but what kind? Has anyone had after market units put on their guns - what kind and are you happy with them.