i can undertstand hand lapping a rough barrel or smoothing it out using bore paste or jewelers rouge. i refuse to grasp the concept of ritual barrel break in. Fouling will accumulate in any centerfire rifle barrel, broke in or not. A few of my rifles like the barrel almost totally free of copper fouling. Three of them require some fouling for peak accuracy. The biggest culprit in barrel fouling is monolithic copper bullets.
For years i fired between 15,000 and 30,000 centerfire rifle rounds every year: This year it was about 10,000 rounds. Among the barrels bought new this year is a Shilen barrel in .22 Cheetah MK 1. The bore of that barrel was hand lapped at the factory. It will have a service life of about 700 rounds; any ritual break in would reduce that barrels life. Nothing is gained by "breaking in" a hand lapped or hammer forged barrel; it's smooth as man can make it. Its not going to accumulate fouling at a fast rate unless monolithic copper bullets are used.
i'm a fan of Gale McMillan, a prize winning benchrest shooter and barrel maker. McMillan calls barrel break in a myth. He goes further:
Another tidbit to consider--take a 300 Win Mag that has a life expectancy of 1000 rounds. Use 10% of it up with your break-in procedure. For every 10 barrels the barrel-maker makes he has to make one more just to take care of the break-in. No wonder barrel-makers like to see this. Now when you flame me on this please [explain] what you think is happening to the inside of your barrel during the break in that is helping you.
http://www.6mmbr.com/GailMcMbreakin.html