Just a comment or two: The portion of the mainspring that functions as
the trigger return spring is in front of the screw in the lockplate supporting
the mainspring at the bottom. You will very likely find that it is better to
reduce the width of the spring in front of this screw, that bears on the trigger.
It works well to remove most of the material from the side away from
the lockplate. Take just a small amount from the side next to the lockplate.
Do not leave to abrupt a corner- transition the width in a gradual curve.
Polish all tool marks out of the spring, and take care to leave no tool marks
that go across the spring at right angles to the length of the spring.
If you leave marks, you are asking for metal fatigue to cause the spring to
fail where the mark is. Go slow and keep the spring from getting too hot.
Quench it frequently.