If at a convenient distance to you, you couldn't do better than J. D. Jones (of SSK Industries) in Wintersville, OH.
I used the gunsmith at Gander Mountain in Reynoldsburg, OH for glass bedding a 458 Lott and was satisfied with his work though he took awhile to complete it.
You can also ship your entire firearm to one of the various companies that does porting. If it's a complete rifle, you can mail it via the U. S. Postal Service; if a handgun, you'll have to go with UPS. If you're just shipping the barrel the U. S. Postal Service is most convenient.
