Focus Focus Focus
First and always focus your eye on the front sight... all else a blur.
Second focus
yourself on the front sight and your mind won't wander off...
If your mind wanders from the front sight... your barrel will
TEND
to drop down just as you fire...
This is a common cause for hunters shooting too low and missing the target.
While focusing on the front sight smoothly increase the pressure on the trigger until the gun fires... as a
slight surprize to you.
You can do it!!! 
