Stubborn Carbon Ring Removal

Mauser06 said:

I'm not convinced that ring matters. I haven't found a way to get rid of it either. Every barrel I see has it right where the case ends. Maybe I'm wrong.

What will kill a barrel is a throat that's fouled up bad. I can actually feel mine with a patch when it's bad. My rod won't spin with the rifling for the first 4-6" or so either.

Only cure I've found is Iosso or your favorite abrasive cleaner. It won't take much. I can have mine cleaned out in a couple minutes and a couple patches.


When mine stops shooting and I clean the throat out, it goes right back to hammering. That ring you show never changes.




If you are that far into the barrel, I'd experiment on it. Clean it till it can't get any cleaner. I'd bet it shoots again. But, Once the throat is all fire cracked, it doesn't take long for fouling to get bad and accuracy to fall off.

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I'm thinking the same, nothing to lose, this barrel doesn't owe me anything and I plan to replace it but I like playing around and hopefully learning something. If I can eek out a few more rounds with good accuracy thats a bonus.

The beauty of it is even if I do get too carried away and damage it its no real loss.

I do wonder if the fact it is a mass produced barrel CHF barrel has a bearing, I`m guessing these don't get hand lapped etc so will never be as smooth as one of the higher end barrels and as such will never clean as well.

Is is Iosso Bore Cleaner? Please see attached picture.

I may struggle to get my hands on this stuff, dont know if it is readily available where I am (Canada).

Are there any alternatives?

Krob95 said:

CLR works wonders forsure. I’ve used it many time to clean carbon rings in my old 6BR

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I have some CLR and I have thought about it.

I have read a ton of info regarding this (a lot from this forum with input from respected folks like Frank Green etc) and the views are wide ranging, one thing that is holding me back is the fact it is not a stainless barrel.

Having said that if I applied CLR via a patch plug, left it there for minimal time (15 minutes) and then cleaned the barrel and chamber thoroughly with Boretech Eliminator or similar in theory that would remove / neutralize the CLR and hopefully get rid of the carbon ring without damaging anything.

XTREM HTR16 said:

Will JB bore brite paste work as well as Iosso?

Asking for a friend.

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What I'm getting here is that so long as it is a mild abrasive it should do the trick.

A thorough cleaning afterwards for the purposes of removing all of the abrasive paste sounds important too, I imagine leaving some in would result in the bullet removing a small amount of metal as each round passes down the barrel.

918v said:

A bronze brush

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Haven't tried that.

I`m assuming we are talking about a bronze brush with a solvent of some kind (Bore Tech carbon remover or similar)?

Culpeper said:

As you can see you've cleaned enough to determine it doesn't matter. You had no signs of pressure as a result of a ring. But you can see another issue that it is toasting. You did good getting 2500 out of it. After 1500 I would have ordered a new one in case it took a while.

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I know 2500 is typical for 6.5CM and I suspect the barrel is trash but I aint too troubled if that is the case as I have other rifles and can wait for a new barrel.

What do you mean by toasting?

918v said:

Yes, run a couple wet patches, let it soak, then run a bronze brush in one direction down the bore 7 times, then a wet patch and repeat several times.

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Is a bronze brush more aggressive than a nylon brush? Can it damage the barrel?

918v said:

Yes it’s more aggressive. It actually removes carbon buildup instead of gliding over it like nylon. It won’t damage the barrel. I run it only one way to prevent wear to the crown. But it’s not going to wear the bore. Bronze brushes have been around for ever.

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Thanks for the info.

I`m taking the rifle out to try tomorrow with it cleaned as per the pics (still some carbon there for sure) but I am going to grab a bronze brush from my LGS and try this out afterwards.

If I can find a procedure thats works it will serve me well for my other rifles (I just built a high end 6BR that is starting to develop a carbon ring), as mentioned previously I dont mind experimenting on this rifle as the barrel is at / getting close to end of life.

I have often wondered if dragging the brush back through the barrel was a good idea so I am going to try only going only one direction as you mention.

One more question about brush size - as the carbon ring is located before the bore but instead where the brass ends (ie bigger than the bore) what size of brush should be used?

This is a 6.5 gun (264") - would a 270" brush be the correct size? Or bigger?

Picked up a bronze 6.5mm brush today, gonna shoot the rifle tomorrow to get a feel for what (if any) improvement there is from the cleaning to date and then have another go at removing the carbon ring.

30cal user said:

Free All works and bronze bushes last one to two cleaning and then you need to pitch them

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Why is that? Do they wear away?

They're surprisingly cheap anyways.

Terry of illinois said:

Go to Alpha munitions web site . Look up the news section scroll down to article by Jim Kauber about carbon ring following his guide on cleaning out carbon ring . Works great take only a little more time and dose great job .

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Is this the one?

Carbon Ring Build-up, Resulting Problems and a Cure​

Though I’ve heard mention of carbon ring build-up it wasn’t until I got to the 6 Creedmoor portion of the large/small rifle primer comparison (last Kauber’s Corner article) was I aware first hand of the problems caused by carbon (powder residue) build up in the bore.
An established carbon ring manifests itself with sudden and progressive spikes in pressure; pressures bordering on the dangerous and in most cases degradation inaccuracy will result. The tremendous amount of heat and pressure transforms carbon fouling into a ceramic coating that is difficult to remove once it has welded itself in your rifling.
Every experienced match shooter, barrel builder, or gunsmith has his or her way of cleaning rifles but most will agree that a hard carbon ring can’t be removed by standard cleaning methods, it has to be scrubbed out. There lies the fine line between effectively removing the carbon ring and damaging your bore by using a compound too aggressive, overdoing the process, or a combination of both.
Not one to attempt to reinvent the wheel or waste time on the Internet trying to decipher the repeated BS from good, sage advice and recommendations, I’ll go directly to those I feel are true authorities based on years of personal experience and an application of said advice in the conduct of their livelihood. When I couldn’t figure out the pressure problems in my Benchmark Barrel built 6 Creedmoor I immediately drove the 20 minutes from home down to Arlington, WA to speak with my long time friends Ron Sinnema and Bill Broderick owner and manager respectively of Benchmark Barrels.
Below is their recommendation for removing the carbon ring:

Cleaning Carbon Ring In Rifle Barrels​

Carbon ring in the rifle bore can affect accuracy, pressure and velocity. It is more likely to occur in cartridges with large case capacity and small bore diameter. Carbon ring is best identified with a bore scope and will appear as dark and cracked areas of the bore. It is usually 1”-2” in front of the throat and chamber or within the first 30% of the bore. If you clean every 100-200 rounds in a suspect cartridge you may need to use the steps outlined below. It is ideal to inspect with a borescope to determine whether you have issues with carbon ring build-up and where it appears in the bore.

1. Clean all fouling and copper from the barrel using your normal cleaning method.
2. Use a coated rod with a quality jag that is undersize by one caliber – use high-quality flannel or cotton patches.
3. Fold a patch for a tight fit without sticking, cut/fold appropriately – it is important that your folded patch is tight in the bore almost to the point of becoming stuck.
4. Most carbon will be 1”-2” in front of the throat and chamber or within the first 30% of the bore.
5. Put a light coat of Simichrome on the patch being careful to place it on the sides of the patch and the front – this keeps the front of the patch from getting wet and the jag from pushing through the patch.
6. Push the wet patch all the way through the barrel in one even stroke.
7. Reapply Simichrome to the same patch as above and clean the first third of the barrel using short back and forth strokes – concentrate your effort on the first 30% of the bore – do this for about 2 minutes being fairly aggressive while keeping in mind that the barrel may warm up slightly, especially with the light contour barrels.
8. The patch will become loose in the bore during your 2-minute cycle, discard it, and create a new one as outlined in step 3. When you replace the patch during a cycle, do not apply more Simichrome, use the media left in the bore with the new dry patch.
9. Repeat steps 3 through 8 for ONLY two cycles*.
10. Clean as normal to remove the residual Simichrome and fouling. The objective is to remove the carbon ring but not to polish the bore to the point of being too shiny.

* If you do not have a borescope, do not exceed the recommended 2 cycle cleaning procedure with Simichrome. If you have a borescope, inspect so you know where to focus your effort and clean until most of the carbon is removed. Some residual streaking etc. is acceptable.


I’ll probably receive a ton of comments about this next statement but I do not recall, after loading and shooting several thousand rounds of 260 and 6.5 Creedmoor with H4350 did I experience much of a carbon ring issue. It wasn’t until I started using RL-16 in the 6.5 to some extent and the 6 Creedmoor primarily did I encounter this problem. When I look down the bore of my 6 after a string, I swear the bore fouling looks the same as the bore of my Shiloh Sharps 1874 45-70 BPCR. Don’t get me wrong though, I’ll continue to use RL-16 in the 6 Creedmoor along with the other temperature-insensitive Alliant powders but rest assured I’m going to stay ahead of the issue by cleaning much more frequently with a solvent designed for carbon fouling removal. So far I’ve had great luck with Bore Tech’s C4 Carbon Remover, though I’m sure there are other solvents that may do just as well.
If you’re experiencing or suspect a carbon ring build-up in your own match rifle, here’s the component recommended for removal of that stubborn ring.

Stay Safe,
Jim Kauber
Alpha Munitions CSO
President / Director of Training
The Site Firearms Training Center