Do You Need to Break in Your New Barrel? (Yes, Here's How)

Finished building your custom AR-15? Bought a new barreled upper or an all-new rifle? Trying to maximize your accuracy and land some sub-MOA groupings at the range? Then you've got to follow the steps below. 

Why You Should Break in Your Barrel

Sure, you've bought plenty of things that came with some sort of "break-in" instructions. Maybe it was a pair of hiking boots, or some leather goods -- and you probably put that new thing to use, promptly discarding those break-in instructions that came in the box.

Gun barrels are a bit different. Some of the country's top barrel makers, like Lilja, Proof Research, Krieger, and Centurion Arms, all agree: You do, in fact, need to break in your new barrel to ensure maximum accuracy and rifling life.

"What does breaking in my barrel do?"

Even a high-end, precision-machined barrel leave the factory with tool marks, rough spots, and small imperfections in the surface of the steel. These spots -- particularly those found in the throat of the barrel, just in front of the chamber -- can accumulate copper fouling and carbon deposits that will be difficult (if not impossible) to remove later on.

These stubborn deposits can have a negative impact on accuracy, and they can shorten the lifespan of the barrel itself.

Breaking in the barrel smoothens and work-hardens these troublesome spots. This helps to reduce copper and carbon buildup in the future, while also making cleaning easier across the lifespan of the barrel. 

Lastly, this break-in procedure ensures each round achieves a more consistent spin rate and velocity as it travels down the barrel, ensuring more consistent shot placement -- in other words, it translates into better accuracy.

While some shooters claim they've "just started shooting" their new barrels and enjoyed good accuracy with no break-in process, the professionals who've spent years fabricating high-end barrels and bench-rest rifles have attested personally to seeing a meaningful improvement in accuracy downrange after following a break-in process.

(Chrome-Lined Barrels Don't Need a Break-In)

Note that chrome-lined barrels will not benefit from a break-in procedure. The chrome coating inside the bore is already hardened, and it cannot be materially affected in a positive way by completing a break-in procedure.

How to Break in a Barrel

No matter the barrel, nor the caliber, the break-in process is universal -- and pretty simple, at that. Follow the steps below to complete the process.

1. Clean the Barrel

Follow this cleaning procedure to ensure the barrel's clean. It's important to go in order to prevent damage to the bore:

1. Scrub the bore by pushing a wet patch soaked in powder solvent through the barrel.

2. Push a bore brush through the barrel. Go back and forth five times, from bore to muzzle, and vice versa.

3. Scrub the bore by pushing a wet patch soaked in copper solvent through the barrel.

4. Again push a bore brush through the barrel back and forth at least five times.

5. Wipe the bore with a dry patch. Complete at least two back-and-forth passes.

2. Shoot a 3-Shot Group

Load up a magazine with three rounds, and fire a three shot group. Then repeat the Cleaning Procedure.

3. Repeat Step One

After firing a three-shot group, repeat the cleaning process in step one.

4. Repeat Step Two

After cleaning again, fire another 3-shot grouping.

Repeat clean-shoot-clean procedure (5) times.

After initial cleaning, firing a grouping, cleaning again, and repeating this procedure five times, your barrel will be broken in. Simple!

"What solvents should I use?"

We strongly recommend avoiding any powder and copper solvents that contain ammonia. Although it is an effective copper cleaner, ammonia is a harsh corrosive chemical that will etch the steel in your barrel, effectively reversing the break-in process and potentially damaging your barrel by opening up pores that can trap copper and carbon fouling permanently.

"Should I oil my barrel after cleaning?"

There is no harm in coating the inside of the barrel with a light coating of oil. Even a thorough cleaning cannot remove 100% of all deposits, so this will help prevent rust and pitting when stored for extended periods of times. Just note that you should wipe the bore free of oil using a dry cloth. The bore should always be dry before shooting.