No disagreement here that you need to sight with the dominant eye.
But it's better to develop the habit of
not closing your non-dominant eye.
It eliminates peripheral vision. Might not be a big handicap when the target is steel or paper, but if you're in a gunfight, you'd better be aware of what's happening around you.
Bad habit to get into. Learn to shoot with both eyes open.
http://www.americanrifleman.org/Gall...&gid=66&id=410