With the Criterion barrels you actually finish ream the chamber AND establish headspace on the back side of the barrel.  If you go the Criterion route be very careful about indexing the timing marks.  I just did a one last Saturday and lined the marks up and reamed the chamber and things went quite nicely.  When I took it out of my barrel vise I noticed the front sight base was canted to the side and the barrel was actually over tightened.  I managed to re-index the barrel purely by visual rules, however doing this resulted in the headspace being a tad longer.  It is still within acceptable limits but a word to the wise...don't ream until you check how the barrel is timed with not only the index marks but the front sight as well.

Rick H.

If the barrel is worth saving Fred, I would have tried a new bolt body first.  What did you end up doing with your rifle?