My gun shoots low, and the owners book says that by changing the shims will alter point of aim, but don't say which one does what.

Question is, I have the "B" shim in now as it came from the factory. Do I need the "A" or "C" to raise the point of aim?

TIA

wow I had to alter the washer in the buttstock so I could use TWO shims, because I was seeing too much rib!....you need less shim angle...you need the thinnest shim...if I remember right the SBE book I have gave the info you need.....remember to use the correct washer as well!...I just made some parts out of ss for my benelli because of problems with salt water while waterfowling...the plunger parts in the action spring follower got rusted stuck..and I sheared the nut trying to unscrew it......if I can get a picture up