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Basics

1) Never shoot a new gun before cleaning it to remove oil and preservatives. Always make sure that a barrel is dry before shooting (remove all oil, solvents and preservatives).

2) Use a plastic coated rod, bronze brush flannel patches and a quality solvent. I also recommend a bore guide

The following was provided by Lilja Precision Barrels

We are concerned with two types of fouling: copper fouling, which is caused by bullet jacket material being left in the barrel, and powder fouling. During the first few rounds a lot of copper fouling will be left in the barrel. It is important to remove this fouling completely, after each shot, to help prevent a build-up later on. Powder fouling is ongoing, but easy to remove. Do not use moly-coated bullets during the break-in procedure.

Break-in Procedure

For 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. This is followed 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.

Normal cleaning

For a normal cleaning (after a string of 10-25 shots) after break-in, the above procedure should be used, but stop short of soaking the barrel with the strong copper remover. A good rule of thumb is to stroke the barrel with a brush, one cycle for every shot fired.