Re: Rem 700 \"Embellished\" receiver
It depends on how the receiver is mounted in the jig and the design of the jig itself in some cases. Not all actions are trued up in the type of jig Kirby and I use and I suggest you might ask him what he does to protect the outside surface. Copper, aluminum, or brass should be between the fixture's alignment bolts and your action.
As, or more important "to me", is an understanding of how your action is trued... so you know it really is true, and not your smith just thinking/saying it is, or that it's close enough, or he makes it worse God forbid.
I'm "not" saying that you will "not" end up with a perfectly trued action and his method of achieving this is not sound but, I am saying most (probably 98+%) smiths (there's a bunch out there is why) out there do this
incorrectly (for a number of reasons), and/or they skip certain things they deem unnecessary. You pay the price, and with this type of service you very rarely get what you pay for, or expect.
Back to your point though, most smiths will ensure your finish is not altered, as is expected of them.