There are huge differences between mass produced factory rifles and custom made barrels by barrel makers...
You will find varying opinions about barrel break in...
...some say do it
...some say don't do it
...some even go so far as to say it is recommended by barrel makes so you will wear your barrel out faster... (That’s a myth)
...some even get pissed off talking about it
I particularly like what Lilja has to say about it.
"It is important to break-in a barrel though. The jacket material must be removed after every shot during the initial few rounds. If this isn't done the areas of the barrel that fouled will tend to pick up more fouling and it will build on itself. It is important to get a layer of powder fouling on top of the lands & grooves. This hard deposit will prevent the copper from stripping off the bullets. However, if the internal finish of the barrel is too rough the barrel will never be completely broken-in and fouling will always be a problem. Some barrels can't be broken-in. "
...there are breaking in procedures if you wish to do it. Factory barrels are considerably different than custom match grade hand lapped barrels.
I am going to post one method.
Breaking In A Barrel - Read fully before starting the procedure
When cleaning, always use a good bore guide and a good rod.
Start with a clean, lightly lubed barrel, fire one shot, then run a loose patch through with Sweets 7.62 or any other solvent that will “eat” jacket fouling. Saturate the bore and let it sit a few minutes. Sweets indicate jacket fouling with a blue colour.
Run patches through to dry the bore and then wet patch it again and saturate the bore. After a few minutes dry patch it again. Repeat until the jacket fouling is removed (no blue patches). That means the barrel is clean.
After cleaning with Sweets, brush with Hoppes #9 and dry patch the bore and then leave it slightly lubed with a wet patch of Hoppes #9 before firing.
Then fire one more shot, and repeat the above procedure. Do this for a total of 10 shots, and then proceed to fire 2 shots and then clean as above, for 10 more shots. (For a total of 20.) The barrel is now broken in. It should be cleaned after every 20 or 30 shots there after if possible, or less often if fouling is not a problem.
You will find when the bore is broken in properly; the cleaning procedure is very quick, because there is very little jacket fouling in the bore.
I prefer Sweets 7.62, because it shows “blue” if there is any jacket fouling. I never use a copper or bronze brush with Sweets, because it will eat them, and give a false blue indication of fouling. I never let any other chemicals mix with Sweets. That is why there is a lot of dry patching and swabbing with rubbing alcohol and dry patching between switching chemicals.
For storage after cleaning with Sweets, dry patch and then swab the bore with several patches using rubbing alcohol; this will dissolve any remaining ammonia. Then lightly oil the bore.
Here are some links to various barrel maker's break in procedures:
http://www.kriegerbarrels.com/Break_...246-wp2558.htm
http://www.shilen.com/faq.html#question10
http://www.riflebarrels.com/articles...el_fouling.htm
http://www.pac-nor.com/care/