for what its worth:
Here's what Shilen barrels says:
"Here is our standard recommendation: Clean after each shot for the first 5 shots. The remainder of the break-in is to clean every 5 shots for the next 50 shots. During this time, don't just shoot bullets down the barrel during this 50 shot procedure. This is a great time to begin load development. Zero the scope over the first 5 shots, and start shooting for accuracy with 5-shot groups for the next 50 shots."
And from Krieger:
"Because the lay of the finish is in the direction of the bullet travel, very little is done to the bore during break-in, but the throat is another story. When your barrel is chambered, by necessity there are reamer marks left in the throat that are across the lands, i.e. across the direction of the bullet travel. In a new barrel they are very distinct; much like the teeth on a very fine file. When the bullet is forced into the throat, copper dust is released into the gas which at this temperature and pressure is actually a plasma. The copper dust is vaporized in this gas and is carried down the barrel. As the gas expands and cools, the copper comes out of suspension and is deposited in the bore. This makes it appear as if the source of the fouling is the bore when it is actually for the most part the new throat. If this copper is allowed to stay in the bore, and subsequent bullets and deposits are fired over it; copper which adheres well to itself, will build up quickly and may be difficult to remove later. So when we break in a barrel, our goal is to get the throat polished without allowing copper to build up in the bore. This is the reasoning for the "fire-one-shot-and-clean" procedure."
And from Pac-Nor:
"Shoot one, clean, for first ten rounds; shoot three, clean, for next thirty rounds; shoot five, clean, while working up load. Allow bbl to cool to the touch before testing a new load to avoid unnecessary throat erosion."
From Dan Lilja:
" We recommend that your new Lilja rifle barrel be properly broken-in to obtain the best accuracy. A proper break-in will help ensure that your barrel will clean easily in the future and that you will achieve maximum accuracy potential. Please follow these important instructions.
For an effective break-in the barrel should be cleaned after every shot for the first 10-12 rounds or until copper fouling stops. Our procedure is to push a cotton patch that is wet with solvent through the barrel. This will remove much of the powder fouling and wet the inside of the barrel with solvent. Next, wet a bronze brush with solvent and stroke the barrel 5-10 times. Follow this by another wet patch and then one dry patch. Now soak the barrel with a strong copper removing solvent until all of the blue mess is removed from the barrel. The copper fouling will be heavy for a few rounds and then taper off quickly in just one or two shots. Once it has stopped or diminished significantly it is time to start shooting 5 shot groups, cleaning after each one. After 25-30 rounds clean at a normal interval of 10-25 rounds. Your barrel is now broken-in."
And this is the kicker from Hart barrels:
"We do not believe that a break in procedure is required with our barrels. If you follow our normal cleaning procedure, outlined in this brochure, you should not have any problems with your new rifle. You always want to clean your rifle as often as your course of fire will allow. If you have time to shoot one and clean, that would be fine, but we personally do not feel it is necessary."
