mavt wrote on May 4^th, 2020 at 12:57am:

The bare bolt closes easily on a dummy round with no pressure at all felt against the case or bolt lug. I also tried the full assembled bolt on a new 30-30 case and it chambered and extracted with no issue if any meaning can be derived from that.

When you close the bolt on a case with no extractor on the bolt besides closing easily can you generate a few thousands of front to back motion on the bolt with light pressure. You should be able to feel this but lubricant on the bolt may make the movement hard to discern.
If so a head space issue is completely off the table.
That leaves you with 3 possibilities. Least likely is a serious ding in the extractor that prevents it from entering the extractor slot. The 2 more likely problems are the extractor slot is not deep enough or slightly out of alignment when the barrel was tightened. The one you could do something about is if bluing salts leaked into the slot after bluing and hardened in the slot. Before you send it off, flush this out with spray penetrating oil and pick in there to loosen the granules up, flush again. Then blow it out with compressed air.  I had a bunch of salt come out of the threads on my dad's 1917 Enfield when it was blued.