Just acquired new Cordoba, In patterning with various chokes I note that with several chokes the majority of pellets are in the NW &/or NE quadrants of a 30" circle. I shot from a good rest with bead aimed at center of target. Is this "normal" for a shotgun, I assume that I could adjust for it by holding the bead just below a target with a proper lead versus covering the target. Or is a better approach to shim the stock? Obviously I am new to shotgunning & would appreciate some sage advice from those of you who know what they are doing.