Re: Gunsmith to cut down, re-crown, and thread barrel
That top pic looks like a profile for an OpsInc 3rd. Your adaptor should have some installation instructions...probably a sheet with measurements. Be sure to include that sheet with your adaptor when you send the package off.
When I had 737Shark thread my barrel, I brought him the whole rifle. He pulled the barreled action out of the stock, then removed the rings from the base (scope stayed in the rings) and left the base installed on the action.
If I were going to send it off to have the barrel threaded, I'd pull the bolt, base, rings, scope, and stock. This'll save on shipping and keeping your parts where you know they are. Even the best of people make mistakes, and if you strip it all down prior to shipment, then it can't get misplaced at the 'smith.
When you go to reassemble the rifle, you should just need some small torques...probably between 15 and 80 inch pounds as a range for the entire assembly. Hit up Sears for an inexpensive, repeatable tool.