I had my model 70 rebarreled in 264 by Pac-Nor. It came back with a pamphlet detailing a specific break-in procedure, and included a bottle of "Witch's Brew" solvent/cleaner for the job.
This is not to say that any components or battel life was wasted in the break in procedure. A certain amount of bullets and powder were consumed in load development. Shooting was interupted as recomended by the manufacturer and the barrel scrubbed.
This barrel is as accurate as any I have ever shot.
Would it have been as accurate without the extensive cleaning procedure?
We will never know.
