Some sort of a trigger adj screw there,,set trigger,,or just a take up adjustment.
Maybe the sear was 'adjusted' as well trying to get a better trigger pull at some time in the past and has ended up a bit shorter than it should be.
Maybe with that trigger adj screw in place, the sear nose needed to be shortened for it to drop into place at FullCock.
Now you have the hammer sitting too far forward as a result.