I wouldn't recommend AR Bunker they are a bunch of snobs. I would go see Ray up at moss pawn and gun in jonesboro. Atl Range and Ordinance may be able to do it in Newnan, but I am not sure.
I have used all of the above, I am pretty sure you will be the happiest with Bob Simms Custom Firearms in Palmetto. Trigger Job Bob has been in the business his entire adult life—he is over sixty. Barrel threading, scope mounting, shotgun choke tube installs, light repairs, and trigger jobs are his specialty. Although he can do any size job, and has in the past, he does not seem to like the bigger jobs anymore.
He has always called me to pickup the gun sooner than expected. He is good, and fast. Prices are fair.