Breaking in a new rifle is essentially the same as breaking in a new barrel. Barrels with cut rifling tend to be rough unless they have been "lapped", a process used by custom barrel makers, but not, to my knowledge, by rifle manufacturers. The break in process either complements or replaces lapping.

The first few shots through a cut rifled barrel are important because they tend to remove the jagged edges left by the cutter. Button rifled or hammer forged barrels are not as rough, but have their own issues. The "smoothing" process carried out for the first few shots through the barrel unfortunately leaves a residue of copper fouling in the rough spots which, unless removed, will be forced into the uneven spots in the barrel and inhibit the smoothing process.

This is most important for target or benchrest shooters, but the owner of an expensive rifle would do well to use the same process, which is time consuming and somewhat onerous, but will result in a barrel which will deliver stellar accuracy for thousands of shots. My large bore target rifles were usually good for 6000 rounds before their accuracy weas no longer acceptable. This assumes having the barrel shortened and rechambered after 3000 shots. If the barrels ahd been long enough to permit shortening a second time, probably another 2000-3000 rounds of accurate life would have been possible. The only really discernable wear to any of them was to the throat area, directly in front of the chamber.

This method was taught me by a gunsmith who dealt exclusively with benchrest and target rifles involved no use of brass brushes whatever. All the cleaning was done from the breech end and employed a close fitting rod guide and a one piece plastic or nylon coated rod. Rods, rod guides and jags are best obtained from a firm such as Sinclair International http://www.sinclairintl.com/ which specializes in benchrest and target rifles.

First the rifle is placed in a secure support, either a commercially made cleaning stand, or an improvised one, made by cutting notches in opposite sides of a large cardboard box. Then the rod guide is placed in the rifle action, replacing the bolt. This centers the rod in the action, assuring that it will not rub against the throat of the chamber, holds the patch on the jag, and prevents any cleaning solvents from coming into contact with the trigger mechanism or stock.

An appropriate sized jag is fitted to the rod and a patch wrapped around the jag and inserted into the rod guide. (I generally use square flannel patches 2 1/2" on a side.) The rod is slowly pushed through the bore until about half of the patch protrudes from the muzzle. Bore cleaner (Hoppe's, Shooter's Choice, etc.) is applied to the patch and the rod is worked back and forth ten or twelve times. The wet patch is removed and the bore cleaned with a dry patch.

The barrel is cleaned after each shot for the first ten shots, then after every three shots for the next thirty shots, then after every ten shots for the next hundred shots and finally, after each day of shooting, which in my case, amounted to 66 to 88 shots, depending on the course of fire.

An occasional treatment with J-B Bore Compound should remove all traces of fouling and polish the bore bright. Solvents such as Sweet's, which contain a good deal of ammonia, should be used sparingly and should not be allowed to remain in the bore for any length of time. All traces of them should be removed after use.

As noted elsewhere, the manufacturers preservatives, oil and grease, need to be removed from the bore before the first shot is fired.