I checked which mount I'm using on my AirHawk while home for lunch, and it's an RWS C Mount, not the B-Square. I took the stop pin out of it since the rifle has a pretty good scope stop already, so that wasn't an issue (early ones had rounded stop pins that gouged rifles, later ones have proper stop pins). I googled for you and found one for $30 from
R & R Arms, wihich is about what I paid for mine used. Great price.
Tom Gaylord has compiled a whole list of his blog postings that you may find useful under the title
Adjustable scope mounts. He deals with why the zero might wander in a couple of different postings as well as how to use adjustable mounts. Well worth reading through all of them.
One thing. My mount adjusts for elevation, windage, and the rings tilt, so I must have a later, improved version or something. Dunno, but it holds and hasn't bent my scope, so I'm happy.