I can sense that you're an old 60's apprentice like me Flying10. But as an Armourer, I have to say that I would be MOST reluctant to remove a barrel especially if I could machine a tapered collar that I could nip tightly onto the nocks form. Then have that collar running in a bearing. Or have that tight collar housed in the lathe chuck....... You get my drift.

But certainly, machining everything to the mechanical axis of the bore is the way to go. But be warned that in the worst case, some bodies are so worn at the rear that the bolt can seem as loose as a sausage in the high street as they say in the best circles. To the extent that the sear can interfere with the underside of the small locking lug as the bolt is reciprocated. This means the torch.........

Great thought provoking subject Tom. (From this years SD)