There is a great deal of misunderstanding about the issue of eye dominance in regard to pistol shooting. When the pistol is at extension, eye dominance is irrelevant. All the tests to check dominance actually prove this... your brain puts the gun where it needs to be.
For detailed explanation of Sight Alignment and Sight Picture issues related to defense pistol shooting, watch these:
Part I:
http://www.youtube.com/watch?v=k_AbAfZtTpk
Part II:
http://www.youtube.com/watch?v=NUy46J9IAOM