Barrel Break In Procedure – CBI

It is not unusual for us to receive a number of questions regarding barrel care soon after a customer purchases their first Criterion barrel. Oftentimes we receive questions relating to barrel break-in procedures. In this article we have set out to cover some break-in basics and answer a few other commonly asked questions.

What is the best way to break-in a barrel?

There is no single ideal way to break in a rifle barrel. A shooter could spend hours scouring the web and find dozens of different methods. Some may be more effective than others, but there is no one-size fits all process suited to each unique barrel. We can offer a number of basic steps that can be taken to help get your barrel competition ready. A number of other variables will also serve to influence your break-in process.

Why should I break-in my barrel?

The purpose of a barrel break-in procedure is to limit buildup of copper fouling. An excess of copper fouling can serve to increase chamber pressures, reduce velocity, negatively impact bullet stability, and decrease barrel performance.

What causes copper fouling?

Reamer rings and poor finish may cause significant levels of copper fouling. While all barrels may experience some degree of fouling, the amount left behind will vary by manufacturer and barrel model.

What helpful tips can you provide regarding the break-in process?

Some helpful points to consider are listed below:

• A bore guide, coated rod, and brass jag should be used throughout the break-in process.
• Bore guides are especially important when breaking in rifles that are cleaned from the muzzle.
• A damaged crown can cause a catastrophic decline in performance, and should be avoided at all costs.
• Bore brushes are unnecessary, and tend to provide false coloration by removing copper residue from the brush itself.
• Keep patches centered on the jag when running them down the barrel. Off-centered patches may cause the jag to run down the side of the bore, damaging the finish.
• Be sure to read the instructions listed on the package of your bore cleaner. Some compounds will list different application requirements that need to be followed in order to prevent damage to the barrel.
• Some corrosive solvents should be not be left sitting in the barrel for an extended period of time, and may eventually eat into the finish of the barrel itself.
• Solvents may occasionally lose effectiveness after repeated use, and will require the subsequent use of another compound to regain their ability to remove any remaining copper fouling.

What process can I use to break-in my barrel?

With the goal of gradually reducing copper fouling, we suggest beginning the break-in process with single shot groups. After each group the shooter should clean the barrel with a copper solvent. When fouling begins to diminish after each shot, group sizes can be subsequently increased to five rounds. When fouling is reduced after each five round group, the group size can be increased to ten rounds. If the barrel has no copper fouling after a ten round group, your rifle is ready for your next match.

The removal of copper fouling is important, but the most important factor in barrel maintenance is the removal of all moisture. Trapped water will wreak havoc on barrel performance, so make sure to run a few patches through after each use to ensure no condensation remains on the rifling.

How can lapping influence barrel break-in?

Lapped barrels such as those sold through Criterion Barrels generally do not require a significant break-in process. The throat finish is generally not lapped, so this is the area that may require breaking in. The quality of reamer used may also influence the amount of break-in required.

What benefits does chrome-lining offer for break-in?

One guaranteed way to reduce copper fouling and ensure an easier break-in process is the use of a chrome-lined barrel. Copper fouling serves to attract moisture from condensation, which will serve to corrode exposed surfaces. This is especially prevalent with a barrel that features  an alloy composition that lacks a chrome-lined finish.

Chrome-lined barrels have traditionally held a reputation for featuring slightly reduced accuracy potential. During the typical chrome-lining process material is chemically removed from the bore and then built back up with chrome, destroying the bore uniformity.

At Criterion Barrels our unique chrome-lining process maintains bore uniformity, providing you with the advantages of a chrome-lined barrel without sacrificing accuracy.