Bruce,
The set screw just behind the full cock (sear) notch will reduce the amount the sear engages the sear notch.
Firearms, like most Military arms have no provision to keep the sear from engaging the half cock notch if too much of the full cock notch height is removed.
Firearms set up with either double or single set triggers use a "fly" that helps the sear or sear part of the trigger slide over the half cock notch.
Set trigger firearms will have a small set screw on the outside of the trigger plate. This allows the shooter to make small adjustments to the trigger pull, without having to remove either the trigger and/or lock plate to make the adjustment.
Hope this helps?
My best,
Blair