I think there is more behind the thread and chamber to what you are asking than cut vs button accuracy. Barrel life depends on treatment and cleaning from what I have been told by guys that shoot rifles like I do pistols. Get it hot and keep beating on it and they won't last as long. I have had a few Shilen barrels and just got a quarter bore in the mail a few weeks ago. I will try to keep it long enough to break it in this time. You will be fine as long as the guy running the lathe knows how to make shavings.
