Take it with a grain of salt, but I always break in a new rifle per the method listed above. If I get a used one I usually lap the bore with JB compound. I think that the break-in is more for ease of cleaning by removing the minute burrs on the rifling that catch and hold fouling than for accuracy. These burrs will eventually be removed through constant firing and cleaning after shooting but will take longer. I find that a good number of my rifles will shoot better after a couple of fouling shots. With these rifles, I shoot them just prior to a hunt and do not clean them until the hunt is over.

I know alot of people use JB bore compound but it is a big mistake unless your rifle is badly copper fouled.Lapping compound used in a new barrel can be a mistake the lapping compound can round the lands in your new barrel which you want to keep nice and sharp.I have had people bring me rifles that used JB so much that they ruined the rifling in the barrel.If you use it be careful!! I will not ever put JB compound in any of my rifles.

Heres what I do to all my rifle regardless if they are factory or custom barreled:

Clean thoroughly before shooting.

Clean thoroughly after the first shot.

Clean thoroughly after a two shot group.

Clean thoroughly after each three shot group. for ten groups.

Clean thoroughly after each five shot group, for the next ten groups.

Then I clean thoroughly after each range session so long as the session doesn't exceed 20 rounds.

The important thing is to not allow the barrel to overheat. You will notice that the bore becomes easier to clean after each session. In the beginning the barrel will foul extensively. After about ten groups you will notice that the fouling is greatly reduced.

My cleaning method:

1.Push a patch with Hoppe's
2. Scrub with bore brush soaked in hoppe's 10 times and repeat
3. Push multiple patches through bore to remove powder.
4. Apply "Gunslick foaming bore cleaner" and let sit for 10 minutes
5.Patch out "foamer" (may take 2 or 3 Patches)
6. Apply sweets 7.62 copper remover. let sit2 minutes, remove
7. Repeat step 6 until there are no signs of copper (blue patches). Many times there are no signs of copper, the foamer removed it all.
8. Push dry patches until sweets is removed
9. push patch with Montana extreme bore oil.

Its very tedious. And I do not enjoy it at all. But, I can't argue with the results. In the end you will have a smooth bore that is a dream to clean. I've noticed accuracy improvements only in factory barrels that foul exorbantly. Custom hand lapped barrels shoot well from the first shot.