Cross-firing or double vision - eye dominance

It is estimated that 40% of right handed shooters are left eyed dominant while 80% of left handed shooters are right eyed dominant.

A problem for many shooters is wrong eye dominance and crossover sighting. This often occurs when right handed shooters have a dominant left eye and a left handed shooter has a dominant right eye. Many prefer to shoot giving their preferred eye an advantage and find the Magic Eye Dot system to be the answer. You can find more details on the above URL.