What cleaning copper fouling look like

How to Remove Copper Fouling from a Rifle Barrel


Mathew R Reed
March 17, 2022

Keeping your firearm clean is vital to keeping it functioning properly and extending its expected lifetime. One major problem that many firearms will face is copper fouling in the barrel. In this article, we will cover all of the issues associated with copper fouling, as well as how to prevent it and clean it should you ever face this problem with your own firearms! 

What is Copper Fouling and What Causes It? 

Copper fouling is when your bullets leave residue and streaks inside of your barrel as they get shot. If you shoot any bullets with copper, you can try to look down the bore and will most likely see some throughout the rifling. If left untreated, this copper fouling can cause many issues.

Not only can copper fouling eventually pit the steel in humid environments, but it will significantly affect your rifle’s accuracy. This is why it is so important to keep your rifle’s barrel clean and as free from copper fouling as much as possible. 

How to Prevent Copper Fouling

If you shoot any bullets with copper, copper fouling is very hard to prevent entirely. There are, however, a few simple things that you can do in order to slow the build-up and help to prevent it from becoming a major problem. The first thing that you can do is be more selective in the ammunition that you are shooting. By sticking with high-quality competition chamberings, you will have much cleaner barrels and less copper sticking to them. Ammunition such as Hornady’s Match Grade Competition will shoot much cleaner than a box of cheap Winchester rounds in the white case found at any gun store.

Some newer ammunition types even have new powder that supposedly helps to reduce and “clean” the barrel from copper residue. These are polymer-coated bullets that not only prevent copper fouling but actually help to clean bad cases of it when fired. You can find these bullets from Syntech. There’s also abrasive coated bullets that helps you polish the bore and reduce fouling like the David Tubb Final Finish System.

A high-quality barrel will also help to prevent copper fouling, as the copper has a much harder time sticking to a high-quality barrel made from good materials and a good production process. 

The best thing that you can do to prevent copper fouling, however, is to regularly clean your firearm after shooting. Using a good solvent, this will help control and regulate the build-up and prevent copper fouling from ever becoming a major issue. 

How to Clean Copper Fouling

In order to best clean copper fouling, you will need a few basic gun cleaning supplies. Get a hold of some proper solvent, wet patches, a bronze brush, and some dry patches. Start with the bore solvent that will break down the copper fouling, and clean from the rear when possible. Make several patches with the bore solvent and wet patches, making sure to use new patches each time. For extreme copper fouling, you can also let the gun barrel soak for a few minutes in between each patch in order to allow the solvent to do its job. 

Next, use the bronze brush to make several passes as well. Keep the brush wet with solvent, and these passes should free up any copper that the previous patches did not get. Once done with the brush, make a few more passes with a wet patch in order to pick up anything the brush may have gotten.

Lastly, run a dry patch through the barrel to clean the solvent. You will now switch to a copper-removing solvent, using a few wet patches through it before waiting a few minutes. The goal is to get to the point where you can place solvent for a few minutes and have no blue stains on the next patch that you run through. Blue indicates that there is still copper. 

What cleaning copper fouling look like

Even after the patches come out clean, extreme copper fouling can still result in some fouling that is trapped in between layers of powder or carbon fouling. Just to ensure that you get everything, try switching between the two solvents and continue to look down the bore to ensure everything is clean. For extreme cases, do not be afraid of leaving solvent to soak but just make sure that you are carefully reading instructions on the solvents as too long of exposure can start to eat away at the barrel itself. 

Frequently Asked Questions:

Does copper fouling cause poor accuracy?

Yes, copper fouling can and does negatively affect a rifle’s accuracy. 

How often should you clean copper fouling?

Copper fouling should be cleaned as often as it is seen. Many experts recommend cleaning a gun barrel every 25 to 30 shots to prevent copper fouling. 

Can I use a homemade copper fouling solvent?

It is not recommended to use anything other than solvents specifically designed to combat copper fouling in a rifle barrel, as you could risk damaging the firearm. 

Is copper fouling a problem with all firearms?

If any ammunition that you shoot contains copper, copper fouling can occur after shooting multiple rounds and should be taken care of as soon as possible. 

What is the Best Copper Fouling Solvent?

There are plenty of different options when it comes to copper fouling solvents to use. One of the most popular options is the tried and tested Hoppe’s No. 9 Gun Bore Cleaner that can be found just about anywhere gun supplies are sold. However, the Hoppe’s No. 9 is more of a general cleaning solvent. If you want something more specific to copper fouling, Hoppe’s also has High Performance Copper Cleaner. A few other great options include Bore Tech Cu+2 Copper Remover, Pro Shot Products Copper Solvent IV, M-Pro 7 Copper Remover, and Wipe Out 5oz Bore Cleaner

All of these solvents do a great job at combating copper fouling in a barrel and can help effectively clean it. All of these solvents are also great bore cleaners in general, especially Hoppe’s No. 9 Gun Bore Cleaner. By using a quality bore cleaner and regularly cleaning your rifle barrel, you will help to clean off all of the copper fouling before it becomes too much of an issue or starts to affect your firearm’s accuracy

Final Thoughts

Copper fouling is a common problem in firearms that often goes overlooked. By taking the proper precautions and arming yourself with the proper cleaning agents and tools, you can ensure that your guns are free from copper buildup and enjoy a lot more use out of them!

Mathew R Reed

Mathew R Reed is a professional gun seller who runs a dedicated gun store in the suburbs of Oakland, CA. A hardcore hunting enthusiast since childhood, Reed has ample experience with guns and accessories. He is the founder of ArmorHoldings.com and creates some of the most helpful gun-buying guides and explainers. If not in the gun shop, you can find him on the nearest hiking trail or nearby hunting spot.