Save the heartache and ship it out, especially if it needs to be done right (i.e. for a sound suppressor).
I tried the local route, letting someone a dealer recommended do it. Big mistake. It took him a long time to get around to it, longer than if I'd have shipped it, and I still ended up needing to send it out to have it properly redone.
I'm not saying there's no one around able to do it. It's not like it's alchemy. I would love nothing more than for someone to chime in on a local that does excellent threading.
That being said, I'd have to hear the same recommendation from several people before trusting someone now.
I'd bite the bullet and ship it to
Adco,
Aquila, or
Tornado. I've used all 3 at one time or another and all 3 did very good work.