I've got an older 243. Barrel seems to be good, but I've got a pit or gouge in the chamber about 1/4" from the bolt face. When I got the rifle home at first, the burrs wouldn't let me chamber a round. I polished the burrs out by hand with emery cloth being careful not to overdo it. The brass is swelling just enough to make extraction difficult.

How tough is it to cut and add threads to the barrel? I've got access to a well equipped machine shop and pretty good Tool and Die guy. If he can pick up the existing threads in the lathe, we should be good to go correct?

From there I just need to finish ream and set headspace when re-installing the barrel, correct?

Just get a new barrel? I kind of like the old barrel with "J-Series" stamped in it.