Carbon Ring - In Pictures

[Dusty Stevens]

Too late Dusty, I already did it. And, Heaven forbid, it still hammers.

Hawkeye shows no issues, or scratches where they shouldn't be.

There wont be. But you can take out .003 without even feeling it cut not to mention what carbon does to your reamer.

 

[Murray Brook]

I brought this very subject up with the smith that built my last rifle and he told me to not use the reamer for carbon ring removal as it may ruin the reamer.

 

[Dusty Stevens]

I brought this very subject up with the smith that built my last rifle and he told me to not use the reamer for carbon ring removal as it may ruin the reamer.

And it wont get in the grooves anyway so just dont do it.

 

[yukonal]

I brought this very subject up with the smith that built my last rifle and he told me to not use the reamer for carbon ring removal as it may ruin the reamer.

My 'smith was the one who told me to do it. DUH!

 

[HIC3540]

Get a 7mm bronze brush and a chamber length cleaning rod. Put a little C4 (or any 'carbon' remover you desire) on the brush and run it in until you fell it hit the freebore. Twist it while giving it some short strokes of under an inch and you will have that ring out of there pretty quick.

Yessir, I will be giving that a try this afternoon!

I did use a normal nylon brush this AM before work, 3 complete strokes full length. That removed the black ring in the neck and the majority of Carbon in the FB, but did not touch the ring. My borescope developed an issue so I have another on order that will be here tomorrow. I will continue with the pictures then. Do you guys know if I become a silver or gold contributor if it lifts the 10 posts in 48 hour rule?

 

[michaeljp65]

A bronze brush slightly bigger than your caliber on your cleaning rod, some solvent a few turns and the carbon ring is gone. So simple.

 

[dc.fireman]

A 60 round string on a 6.5 PRC? No wonder that throat looks a little rough already.

60 rounds is the minimum number of record shots in a 300M English Prone match. That's without sighters.

 

[jamesh]

Yessir, I will be giving that a try this afternoon!

I did use a normal nylon brush this AM before work, 3 complete strokes full length. That removed the black ring in the neck and the majority of Carbon in the FB, but did not touch the ring. My borescope developed an issue so I have another on order that will be here tomorrow. I will continue with the pictures then. Do you guys know if I become a silver or gold contributor if it lifts the 10 posts in 48 hour rule?

Silver and Gold membership information here.
http://forum.accurateshooter.com/threads/member-upgrades-silver-gold.3927916/#post-36995199

 

[golong]

This thread is a bit old but since it was resurrected, I am going to chime in.

The carbon ring that matters is the one that you get at and past the lands, not the one that shows up in front of the case mouth. It is the one in the rifling that stops the patch from going in clean, and also the one the bullet hits. The one in front of the case mouth is not hurting/impacting anything whatsoever - if your brass hits it as it is expanding, its probably just going to scrape it out for you.

If you are concerned about the ring in front of the case mouth, just drop a piece of brass in and see where it lands. This first photo (yes, the case mouth is garbage - just scrap stuff) shows how far back a "SAAMI" max length piece of 6.5 Creedmoor brass sits from the end of the chamber in an in-spec (go/no-go verified) SAAMI chamber. The second photo is a brass at SAAMI minimum.

The final photo is the real carbon ring to pay attention to, if you are going to pay any attention at all. Personally, I feel it with the cleaning rod rather than getting all worried about the photo; if it transitions fine then life is good.

 

[Rustytigwire]

Great photos and info. Thanks to all!

 

[garandman]

Way to "jump in."

Welcome !

 

[jrm850]

never HEARD OF DYKEM. iS THS IT?

https://www.amazon.com/dp/B002KGEP7Q/?tag=accuratescom-20

That single tube is enough to mark every piece of clothing in your whole house. It migrates. Some use that non-drying form for hand inletting stocks. The Dykem layout version dries.

 

[Pwc]

Ok, I know nothinhg about botescopes...
So what am I seeing? In the top two pics, I can see the end of the bress case, then a line of light from the scope, then the dark shadow cast by the end of the chamber, and the edge of the chamber.

What am I seeing in the 3rd pic?

 

[Tim s]

Ok, I know nothinhg about botescopes...
So what am I seeing? In the top two pics, I can see the end of the bress case, then a line of light from the scope, then the dark shadow cast by the end of the chamber, and the edge of the chamber.

What am I seeing in the 3rd pic?

You’re seeing a barrel with a bunch of rounds that is showing fire cracking.
When this gets extensive that barrel is nearing it’s end.
When this begins you can keep going awhile by working it with IOSSO or JB, because they get to the point where that roughness starts to really lay down copper fouling as well.
That really is not a ring and you get to the point where it’s a couple inches ahead of the throat.
If it’s on a match gun, you’re barrel that used to shoot .1’s now shoots .2’s or .3’s or throws shots, and now becomes a fire form barrel.

 

[yukonal]

The carbon ring that matters is the one that you get at and past the lands, not the one that shows up in front of the case mouth. It is the one in the rifling that stops the patch from going in clean, and also the one the bullet hits. The one in front of the case mouth is not hurting/impacting anything whatsoever.

I respectfully disagree. I had one there that was scraping, and changing the seating depth of bullets, as they were chambered. I found it by literally seeing the scratch marks on the bullets.

After the ring was removed, things went back to normal.

 

[golong]

I respectfully disagree. I had one there that was scraping, and changing the seating depth of bullets, as they were chambered. I found it by literally seeing the scratch marks on the bullets.

After the ring was removed, things went back to normal.

I suppose something like that is possible, but in my experience it is the transition to the throat that scratches stuff. Sometimes from fire cracking, sometimes from little pieces of brass getting blown out of the case (from chamfer, primer pocket reaming, etc.) that get stuck on the entry.

This photo shows the transition to the throat. Pretty tall compared to the carbon that gets built up.



As for the carbon ring that forms on the rifling AND for what scratches bullets (again, in my experience), this next shot is better. You will see the ring is just starting to form. If left alone, the ring will get to be pretty long - just as @yukonal said, I have seen them inches long.



Bore cameras make EVERYTHING look like SOMETHING, when in reality most of it is nothing to give a second glance to. I mainly use the camera to make sure I got all the cleaner out of the chamber, and to check for leading with cast bullets. This next one shows that even with a really good bore guide, you can end up with cleaner left behind.

 

[Nature Boy]

I use the 45 cal ram rodz (q tip looking things) to get at the carbon ring in .308 based chambers.

I squirt some boretech carbon remover on it, stab it back and forth into the chamber and the carbon ring transfers from the chamber to the giant q tip. I never have the problem others seem to report. Maybe because I never let it build up

 

[Texas10]

Just to clarify what is being discussed, and for other relative newbies logging in, the carbon ring you are highlighting is at the start of the throat/leade? I can see how removing that carbon buildup would seem to increase CBTO measurements. But is the reamer actually cutting steel? IF so, wouldn't cutting out the gouges seen in the pics be considered a good thing? Better/smoother transition into the lands and grooves?

And is there as second area of carbon buildup that is also a concern? Namely the area just in front of the throat/leade? Where the case mouth end is a few thousandths short of filling the chamber completely? Can't carbon buildup in that area lead to a case mouth pinching a bullet upon chambering?

My endo cameras tell me I'm keeping these areas free of carbon, but maybe I'm not looking close enough.

Inquiring minds....

 

[golong]

@Texas10 correct, 2 rings being discussed. Keeping in mind the following is my opinion...

For the most part, cameras make everything look worse than the really are. If you can control contrast and focus then you have a better chance at seeing what is really going on, but not many cameras have either of those abilities. Same for cleaning - double edge sword on this one. If it is clean you can get a better idea of what the fire cracking/pits/tool marks are really like (fire cracking always looks worse when dirty), but you have to scrub metal to do that. I think shooters forget that barrels are intended to hold up to the heat of the sun, that gun powder is dirty, and that bullets are not all pretty looking when the are being shoved down the barrel at 50k psi. You can take the prettiest barrel ever, the prettiest bullet ever, and by the time you get that pretty bullet to the opposite end of the pretty barrel no matter the method, neither is going to look pretty.

The ring at the end of the case mouth (what the OP was talking about, but what you have as the 'second area') is easy to maintain with a chamber mop. You can get special tools such as what Bore Tech has or just use a chamber mop on the end of a pistol. I use the Bore Tech kit and have around 10 chamber mops that I rotate and clean. I never have to take a brush to this ring, and I have never had it impede brass, even before I started using a chamber kit.

The ring that starts at the lands is the area that takes the most heat from the powder and primer, and the most abuse from the bullet. Burning propellant is not kind, and squeezing a bullet (yes, they are being severely deformed to get down the barrel) into the barrel is violent. This in turn is whey the area is susceptible to a carbon ring. Unless you scrub it with a bronze brush or something like JB on a regular basis, it is going to happen. But since the things that clean it are also things that can take away metal, some (like me) just try to manage it while the rest of the barrel is getting used up.

The reamers do cut into this area -- a barrel blank has the rifling grooves, but the ends are cut square. The reamer creates the chamber and transition ramp into the rifling, so yes, it cuts a lot of steel. Cutting the gouges (fire cracking) is done by some - they call it setting back. It can be done, but you end up with a shorter barrel (not necessarily a bad thing) but may also be trying to save dollars with quarters. Barrels are consumables, and fire cracking almost always looks worse than it is. I have barrels that would freak people out yet still manage to allow me to pull an occasional 1/4 MOA at 200 - 300, when I am normally a 3/8 - 1/2 MOA shooter.

Some say the carbon ring in the lands changes CBTO. I say even if it did, you will never know it. Even carefully sorted bullets are off by 0.0005 - 0.0010, and by the time you seat them that variance can double. I will also say that erosion pushes the lands out farther and faster than carbon is going to shorten CBTO. The problem with the carbon is it does cause the bullet to get squished more, then released once it gets past the ring. Kind of like putting a speed bump inside the barrel.