Carbon Ring, what is it, where is it?

[powderbrake]

I have been following this forum, and see lots of talk about a carbon ring, and I am not familiar with it. What is it, and where does it appear? What causes it? How do you remove it? What effect does it have on accuracy?

I want to improve my accuracy and learn more about accurate shooting. Thanks in advance for your instruction on this matter.

 

[260 Ravage]

Good question. I hope those in the know respond.

 

[ShootDots]

It is an excellent question! Picture this in your mind's eye: The cartridge gets inserted into the chamber area. The end of the case mouth ALMOST comes in contact with the "end of the chamber / beginning of the leade of the lands. This "gap" if you will, which is necessary, is an area where the carbon builds up upon firing. If not removed after every round of fire>>>say about 100 with a day's matches or 2 hundred after 2 days, that carbon begins to build and build up rapidly. Before very long, you actually end up with a "barrier" higher than the chamber neck walls and it will take FORCE to push a bullet past it to close the bolt. This will drive pressures up immensely and ruin accuracy. What I do to keep this problem from happening in the first place is, after I use my bronze brush to loosen up the "fouling carbon" in the barrel, I push out the loose stuff first. Then I take an Iosso "Blue Brush", along with Bore-Tech Eliminator and stick it into the neck of the chamber and a bit into the lands. Then I take my hands and "spin" the brush with about 25 turns. Then I short-stroke the neck and about the first 6 inches or barrel and let it soak for awhile>>>>every 10-15 minutes I "spin" the brush and short stroke with the brush, flush with Eliminator. After about 1/2 hour to 45 mins, I spin the brush again in that neck area, scrub out the first 6 inches and push a patch thru. This will keep you from ever getting a "carbon ring"..

 

[avidflyer]

Anyone ever heard of a carbon ring in a 308? For some reason (and I'm probably wrong) I think it affects smaller calibers more. Never even thought about it till I built a dasher

 

[Tim Singleton]

It is an excellent question! Picture this in your mind's eye: The cartridge gets inserted into the chamber area. The end of the case mouth ALMOST comes in contact with the "end of the chamber / beginning of the leade of the lands. This "gap" if you will, which is necessary, is an area where the carbon builds up upon firing. If not removed after every round of fire>>>say about 100 with a day's matches or 2 hundred after 2 days, that carbon begins to build and build up rapidly. Before very long, you actually end up with a "barrier" higher than the chamber neck walls and it will take FORCE to push a bullet past it to close the bolt. This will drive pressures up immensely and ruin accuracy. What I do to keep this problem from happening in the first place is, after I use my bronze brush to loosen up the "fouling carbon" in the barrel, I push out the loose stuff first. Then I take an Iosso "Blue Brush", along with Bore-Tech Eliminator and stick it into the neck of the chamber and a bit into the lands. Then I take my hands and "spin" the brush with about 25 turns. Then I short-stroke the neck and about the first 6 inches or barrel and let it soak for awhile>>>>every 10-15 minutes I "spin" the brush and short stroke with the brush flush with Eliminator. After about 1/2 hour to 45 mins, I spin the brush again in that neck area, scrub out the first 6 inches and push a patch thru. This will keep you from ever getting a "carbon ring"..

Excellent write up.
It really does take this amount of effort and steps laid out to keep it at bay.
My bore scope made me a believer

 

[BoydAllen]

I am going to politely disagree. The thing that happens at the end of the neck part of the chamber is real, but I believe that there is some confusion on the terminology, or perhaps there is a need for some clarification. The material in that area is simply powder fouling that stacks up (more or less depending on the powder)in an area where "normal" cleaning methods may not be effective in removing it. As the poster stated, it can be a problem, and should be dealt with in normal cleaning. One thing that was not mentioned is that if cases of different lengths are used, powder fouling left from the use of the shorter cases, can impinge on the mouths of longer cases, affecting consistency of bullet release. Getting past that for a moment, the other area that needs to be mentioned is the build up of what is generally referred to as hard carbon. This material is powder fouling on steroids that has been transformed by pressure into something that cannot be removed by any chemical or brush. It can be seen right where the freebore starts, at the top of the chamfer at the end of the neck part of the chamfer, very slightly down the barrel from the powder fouling buildup that was previously described. It can also be found in the back end of the bore, usually in the back third or so of the barrel. Various procedures involving the use of IOSSO are the most effective means of removing these deposits. I use a method that I learned by reading how Tony Boyer did is back in the late 90s, and have not changed it. More recently the manufacturer has a different set of instructions. I assume that they work as well. Some powders such as 133 do not have this problem.Others do, to the extent that for types of shooting that involve extended strings between cleaning, such as varmint shooting, that this may be a major factor in powder selection. One example would be using VV 140 in the .204 Ruger. Shooters have found that the hard carbon buildup was so fast and extensive that a change in powder was required. A middle ground powder may require treatment every hundred rounds or so to stay ahead of the problem. None of this can be properly evaluated without the use of a bore scope, except to say that I did this and the problem went away.

 

[Tim Singleton]

Which ever name you call it carbon or heavy powder fouling
This deposit of material at the case mouth that doesn't comes out very well if at all with the normal bore cleaning. Has to be addressed seperatly with an over size brush and isso or JB scrubbing this area clean

 

[lurcher]

So for removing the deposits Boyd speaks of, the hard carbon, I have used JB's and an undersized brush with a cloth wrapped around it short stroking the barrel, I have always been nervous about using an abrasive and I would be interested to hear how other people go about it

 

[jlow]

Which ever name you call it carbon or heavy powder fouling
This deposit of material at the case mouth that doesn't comes out very well if at all with the normal bore cleaning. Has to be addressed seperatly with an over size brush and isso or JB scrubbing this area clean

That's my experience. If you ever had to scrape the hard carbon on the tail of an AR-15 bolt, you know how hard that stuff is. No amount of wiping with a patch will get that stuff off. It has to be scrapped off.

 

[jlow]

Here is a graphic from Tony Boyer's book "The Book of Rifle Accuracy", page 156 that shows where the carbon ring would be.

 

[mikecr]

in my experience, the best way to mitigate 'problem' chamber end buildup is trimming to tight chamber end clearance.
This creating a higher angle for blow back egress, preventing it from building under chambered case mouths. This, along with tight neck clearances, can eliminate neck sooting.

 

[dkhunt14]

Here is a graphic from Tony Boyer's book "The Book of Rifle Accuracy", page 156 that shows where the carbon ring would be.

View attachment 993040

But it also forms ahead of that in the leade or throat. It just takes more aggressive cleaning rather then just patching. Bore Tech C4 seems to help at keeping it cleaned out. Matt

 

[jlow]

But it also forms ahead of that in the leade or throat. It just takes more aggressive cleaning rather then just patching. Bore Tech C4 seems to help at keeping it cleaned out. Matt

There is really no physical barrier preventing the ring from forming in the leade. I would think that all that area in front of the case mouth is fair game, I think it is just a stylized drawing.

 

[CaptainMal]

Seconds on the Bore Tech C4. I had serious problems with carbon-buildup in one of my earlier Dasher barrels. Near blew primers and cases out with pressure on what were normal loads.

You flat out must use some form of carbon cleaner to keep barrels clear of the problem. Varget is one of the worst powders that will create the problem.

 

[jpx2rk]

Seconds on the Bore Tech C4. I had serious problems with carbon-buildup in one of my earlier Dasher barrels. Near blew primers and cases out with pressure on what were normal loads.

You flat out must use some form of carbon cleaner to keep barrels clear of the problem. Varget is one of the worst powders that will create the problem.

What leads you to say Varget is "one of the worst" ? Just curious, not being argumentative.

What are the other powders that are "bad" for contributing to the dreaded carbon ring??

 

[dkhunt14]

What leads you to say Varget is "one of the worst" ? Just curious, not being argumentative.

What are the other powders that are "bad" for contributing to the dreaded carbon ring??

Sometimes it is not the powder, but where the pressure is at. Higher pressures burn powder better and cleaner. Also the cleaning regimen of the rifle. One of the best for keeping carbon out is Bore Tech C4. You can let it soak and it won't hurt the barrel. It seems to soften and remove it. Once it gets built up it gets really hard and then takes mechanical action to get it out. Matt

 

[Nude nut]

As I live a few hour away from any decent gun store I used mercury combustion spray a few years back and havnt used anything else since it does a great job on carbon.

Cheers Trev.

 

[comagutsa]

how often do you guys clean this out , i have just built a 6BRX and want to keep on top of it .. eg every 200 rounds you clean the ring out ?

 

[johara1]

The two places that you can get a build up that will hurt accuracy. The front of the chamber and the end of the case, left go it will migrate back the neck and effect bullet release and could and does raise pressure. The second is in the throat, I was changing free bore with a uni throater,with the same pilot in it and after the barrel was cleaned it would not go back in. Carbon had built up enough not to let the pilot go in the bore, cleaned with Iooso it entered freely. That is about a .0002 build up, in a short time. Both will get you if left go, so i clean as often as i can to keep it in check. I don't think you need to use iosso all the time but a light cleaning will slow carbon down.... jim

 

[charlesasmith]

Boyd:

Thanks again for providing a thoughtful, non-judgemental, and detailed explanation.

Chuck