I might have one reference with a little write up. I'll check tonight.
I have some surgical grade stones I used on the last AR I assembled. I did not get aggressive, I just cleaned up the worst of the surfaces. I have no idea what the pull is, but it's a hell of lot smoother than most stock triggers.
I always figured I would really dig into a stock trigger one day and polish the living crap out of it then reharden the sear surfaces in Kasenit. All of these parts don't cost much, so it won't cost much to experiment.
I got my stones from a man at Friendship, Indiana during one of the NMLRA shoots. Brownell's sells similar stones. Go slow, keep everything square, and assemble the parts a few times as you go to see if there's much progress. Magnification and a good light will help, don't scrimp on the light.
Here's a little trick that has been around a while that helps, too:
Go to
http://www.artactical.com/ , to the Gear for Sale forum, then to AR-15 Drop-In Trigger Adjuster $20 Shipped . The web site belongs to a friend of mine,
DOC is one of his customers.