Educate me on this infamous thing called a Carbon Ring.

[Wrench]

Powder choice and how the bullet slugs up or what can be called "dwell time" as well as brass fit and throat finish all contribute to induce or reduce carbon. There's been some powders that claim to reduce copper fouling which may have an effect on carbon.

 

[Wrench]

One interesting thing I noticed when re26 was going to be my last powder was that it built carbon but not in the throat, it did so halfway down the barrel.

 

[83cj-7]

One interesting thing I noticed when re26 was going to be my last powder was that it built carbon but not in the throat, it did so halfway down the barrel.

That’s exactly what happened to the guy I know. That was with RL26 as well.

 

[The Guide]

I believe it's mainly a PRC thing. In other words, cartridges designed with tighter than average tolerances. I have a 7PRC and it builds up a carbon ring.

Carbon rings are far from "a PRC thing" as it was common and well known long before the PRC family was born.

Is it due to increased use of suppressors?

I've seen more carbon ring issues on rifles with no muzzle devices than I have on suppressed rifles. Not saying that on some rifles that might not be a contributing factor but the worst I've ever seen was a plain sporter rifle using factory ammo.

My wife had great results in her 7mm-08 with the factory Hornady Superformance load with the 129 SST. All of a sudden, she went from shooting sub MOA 5 round groups to shooting an 8" pattern with 0 consistently. Turns out that the particular load they were using in that ammo was causing carbon rings, inaccuracy, and stiff recoil for dozens of people on the internet when I looked into it. We got the carbon ring removed and tried some of the old ammo and some fresh ammo and that rifle would start showing carbon ring signs again in less than 20 rounds.

We swapped her to a 120 TTSX Barnes factory load and no more issues with that rifle. Unfortunately that rifle is an orphan due to Marlin shutting down and losing support for their bolt action rifles. The biggest issue with the Marlin X7 series was the lack of stock parts. The plastic trigger guard liked to crack and you would lose your action screw torque. I was able to find a metal replacement trigger guard for a different model and machine it so that it would work but it was a process to find that aftermarket piece. Support just doesn't exist anymore.

Jay

 

[Fred@Exterra]

I have a theory that I’d like to test one of these days. I wonder if the new “temperature insensitive” powders are more prone to forming a carbon ring. They use a variety of surface coatings on the powder granules to slow down or speed up ignition. These polymers may not completely combust and re-polymerize in the barrel. So, if anyone has a Gas Chromatography Mass Spectrometer or a Attenuated Total Reflection Fourier Transform Infrared Spectrophotometer laying around & a barrel you wouldn’t mind me sectioning, I’ll get right on it


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[Marbles]

If you're not cleaning your rifle you will have a carbon ring. It might not cause you any problems but it's there. Look in your barrel with a borescope and you'll see it.

I borescoped my 223 after 3,000 rounds without cleaning (edit, over 2,000 with certainty, 3,000 is probably rounding up by a few hundred) and no carbon ring. So, no.

 

[brazz04]

I borescoped my 223 after 3,000 rounds without cleaning and no carbon ring. So, no.

Post the picture

 

[brazz04]

223 at 1047 rounds, never cleaned. But that is 100% a ring of carbon at the case mouth going tot he lands. It causes no issue whatsoever, but it's there.

 

[Axlrod]

@270-300

I’m glad you have good luck with your barrels but believe me, you can shoot out a barrel in short order. There are a lot of factors. Powder, barrel steel, how hot you run it etc. I have shot out a .243 barrel in 600 rounds and a 6x45 barrel in 500 rounds. I believe both of them had something wrong with the steel itself which caused them to burn out quickly. When I say shot out, I’m talking about being able to push a bullet 3/4” up in the throat, like nothing left at all, and confirmed with a bore scope. In my 243 barrels I have found that H4350 was a major factor to killing them too quickly. Now that I have been running H1000, I’m past 2000 rounds with only minor throat wear and a tiny amount of checking.

Good luck? He shoots his rifles 10 rounds per year! It would take like 500 years to wear out a barrel.
Something special about a guy that doesn't shoot, giving advice to guys that do shoot.

 

[Marbles]

Post the picture

Well, it has been posted other threads already.

 

[Gadjet]

Well, it has been posted other threads already.

View attachment 1021346

Educate me here. Is that dark stripe the carbon ring? I just got a bore scope and I would like to know what I’m looking for.
Thanks

 

[brazz04]

Correct, here's one in my 6.5 PRC that was actually causing pressure issues after about 40 rounds. Note to self, don't trim brass too short. I cleaned it and measured with a sinclair gauge so I'm only trimming .005" from max case length now. Also need to see if I can get my Hornady trimmer to leave less of a chamfer on the case.

 

[Sevens]

I was in the no-clean camp until I had my 6.5 PRC start popping primers and not even be able to chamber a round due to carbon fouling.

Same, shoot my 6.5 PRC a lot. Didn’t clean the barrel ever, got some pierced primers, learned about carbon rings, cleaned, no issue since. While I don’t love cleaning barrels, I do make an effort to clean them every couple hundred rounds now and pay better attention to if bolt lift starts getting stiff.

 

[mtnbound]

If you're not cleaning your rifle you will have a carbon ring. It might not cause you any problems but it's there. Look in your barrel with a borescope and you'll see it.

I don't care if it's there because it's not affecting anything for me, but I'm trying to understand what causes it and why it affects some but not others.

 

[mtnbound]

I believe it's mainly a PRC thing. In other words, cartridges designed with tighter than average tolerances. I have a 7PRC and it builds up a carbon ring.

I have had a 7PRC and a 6.5PRC and had no issues.

 

[mtnbound]

Not every barrel gets a carbon ring because of not cleaning or being abused. My Krieger 8 twist .243 barrel wasn’t cleaned for 700+ rounds and there was no carbon ring at all. Oddly it didn’t change one thing after cleaning it.

I do know someone that has a 6 CM barrel that develops a carbon ring every 100 or so rounds and accuracy goes to crap. I told him that I’d unscrew that thing and use it as a tomato stake before going through all that BS.

That's what I discovered when I was cleaning barrels. I have almost 400 rounds through my 6CM and have not had an issue. I agree, I would pitch a barrel if it was giving me that kinda issues so fast.

 

[mtnbound]

Is it due to increased use of suppressors?

That was one of my thoughts as well, but I have been using cans for 20 plus years.

 

[Koda_]

I don't care if it's there because it's not affecting anything for me, but I'm trying to understand what causes it and why it affects some but not others.

If you neglect removing it can grow causing pressure problems. Its caused from not cleaning the chamber, it builds up over time, slowly and once set is very difficult to remove. Theres a gap between the case rim and the chambers freebore, it forms there. Borescopes are cheap now, its really good to know how well we clean our chambers, not just the bores...

 

[DB29]

I don't care if it's there because it's not affecting anything for me, but I'm trying to understand what causes it and why it affects some but not others.

A sample of 1 but I think it was short brass that caused mine. Chamber kept shrinking on a new Tikka .223. Found the carbon ring after about 500 rounds. I was using new Nosler brass and reloading it. Seems Nosler likes to go short on brass. Trashed the Nosler brass and removed the ring about 200 rounds ago. I am interested to see if it shows back up using lapua and Norma brass that are longer.

 

[mtnbound]

I was in the no-clean camp until I had my 6.5 PRC start popping primers and not even be able to chamber a round due to carbon fouling. Noticed it in my 243 as well as a 6.5 Creed. Couple factors I believe contribute:

• Overbore cartridges or hot handloads that have lots of powder being ejected
• Use of high back-pressure suppressors
• Cases trimmed too short leaving room between the case mouth and chamber edge

I could probably fix the issue by backing down my handloads, but I'm OK just giving a good bore scrub every 100 rounds or so when the issues show up. Still don't clean other rifles but I'll watch for any issues and clean as needed.

Factory ammo with 308 or 223? Doubt you'll ever see it.

Hot handloads are one of my thoughts. While I have had some hot loads, I tend to keep my reloads in an area where accuracy is more important than speed.
I have been using cans longer than most with no issues, so I don't think that matters.
Had not considered a case trimmed too short.