I have seen a few barrels that people take to me because some factory ammo is producing nearly punctured primers and ejector swipes. I usually ask them for some of the ammo that is doing this and some that is not. About 80% of the time I can just remove the carbon build up at the position you illustrated and the problem goes away. Examination usually shows the case lengths of the various ammos differ by up to 0.025" (223 Rem and 5.56 Nato labeled). Clean the ring and even 5.56 labeled ammo works in most 223 Rem chambers until the carbon rings builds from the shorter necked 223 Rem ammo. Once the carbon ring builds again, the longer 5.56 crimped mouths have no where to go and of course pressure is going to build. Off the shelf tolerances being what they are, means every barrel has to be analyzed as an individual. No one rule fits all.

I've been reading that the brass needs to stay as close to max length as possible, i.e., stop trimming 5-10 thousandths off the mouth of the case. I case that fits at max length, or maybe trimmed only 0.002 from max is more ideal. I've not had time to test this yet but it seems like it would help. I wrap a couple 1 inch square patches over the actual caliber sized bronze brush, coat the outside with Iosso paste, hook up the 24" rod to a drill and get after it. This is after I've used Kano Kroil or Free-All to aid with good spread of the paste. I make sure the patch covered brush does not enter into the freebore. Works for me

I'm more concerned about case donuts, then a carbon ring. Do a video on preventing, identifying, removing donuts. Thanks for making excellent videos!

I've had a pretty bad carbon ring before, and based on info I gathered from barrel manufacturers (Frank from Bartlein in particular), I took an oversized bore mop and soaked it in Boretech C4, left it in the throat area for an hour or so, then took an oversized nylon brush into the throat and manually turned it in place, also occasionally going back and forth around the throat area. That took care of it pretty good, had to redo that process a couple times if the ring is really bad

Great and clearest explanation yet...

Lou Murdica addressed this in an interview from Erik Cortina. He said even a carbon ring 0.0010" into the mouth of the case can increase pressure rapidly. I try to keep the carbon ring out if possible. I prefer to see the ring right at the tip of the case point. Good discussion point. Always nice to see these topics and talking about the tales we spin that are not much more than pure conjecture. I put a little Iosso on a 223 or 308 chamber brush made of nylon bristles, works very well, and its really easy to clean up. 9mm brushes are good for that chamber end and throat. Appreciate this topic!

Great video as always! More please!

In my opinion, your explanation is logical, I buy it,😊

Solid advice

Thank you 🙏

I just clean that area every time I clean my barrel, with a slightly over caliber Iosso brush on a chamber cleaning rod and whatever cleaner I'm using at the time. Use a patch on a slightly over caliber jag or brush to get the crud out afterwards and it's good. Probably fired 300 to 400 rounds before the first time I did that, came out plenty easy despite having a decent little carbon ring going at that point, and I've just kept up on it since on all my rifles

I shot NBRSA a six 6ppc for 24 years, normally cleaned the barrel at 20 shots or less, I’ve never had a carbon ring

Good stuff.

Good video.

Thanks for the informative video. I have a bore scope so I keep up with cleaning and I see if any carbon ring forms. Iosso nylon brush with a patch, bore tech C4. Push it in till you can feel the throat. Let it sit there for a half hour to an hour. Give the cleaning rod 50 turns and the ring is gone. Just a question Kevin, i see when you are conducting load development and shooting competition in F-Class, you use a shooting mat. What shooting mat would you recommend?

Great videos, I clean the carbon ring from my Vudoo 360 with BoreTech Carbon Remover it works great. .22LR match ammo being soft un-coated lead can be deformed and really effect accuracy.

Ever tried FreeAll for carbon ring? Trying it on (typically dirty) 22LR barrel… seems to be effective after a patch soaking (or bite mop) for 1-2 hours and a nylon brush.

Thanks Keith. I have talked to several PRS guys who never clean their barrels. They claim that it shortens barrel life. I'm not sure whether it does or doesn't but I am sure that the inconsistent pressures caused by carbon buildup is not conducive to accurate shooting. And just as a guess, it probably leads to barrels being prematurely scrapped for new ones. keep making the videos!!! God Bless.

These rings weren't even on my radar before this video came out; just copper build-up, which has caused me diminishing precision in the past. But watching the video, I realized I've had the experience of dealing with a tough carbon ring, even though I didn't have a term for it other than "carbon buildup" at the time. When Hawkeye borescopes first came out, my dad got one that we shared. It allowed me to see a carbon ring that had built up in my Service Rifle competition AR. I clean barrels religiously and have never had one of these build up enough to cause a pressure problem. Bronze brushes and Iosso Bore Cleaner (abrasive paste) probably kept them trimmed down enough they didn't matter over the course of a match. However, with the borescope, I could see the darn thing, so it became a psychological irritant. No amount of brushing or abrasive cleaning would clear it 100% out of the bottom of the inside corner of the shoulder at the end of the case neck portion of the chamber. The carbon remained, giving it a sort of 45° fillet. Then one day at Camp Perry, the maker of the then-new Gunzilla bore cleaner was giving away small samples on Commercial Row and talking up how it removes carbon and loosens rust, so I brought one home. After my usual cleaning had removed copper and surface fouling, I looked through the borescope again and was annoyed again at the stubborn ring still being there. So I decided to Gunzilla on it. I ran the usual wet patch followed by a dry patch, which didn't remove anything my regular cleaning had not already removed. But after I ran one last wet patch, and before I could follow with a dry patch, the dinner bell rang, and I had to go wash my hands, got distracted, and didn't return to the bench. I didn't remember the wet bore until the next day, when it was about 18 hours later. I then ran a dry patch through, thinking the original might have dried (it hadn't), and that patch came out of the muzzle with a perfect little black ring around it where it covered the tip of the jag. I got out the borescope. My little nemesis was gone, and the inside corner was perfectly clean. Some years later, I ran into the Gunzilla makers at the NRA Annual Meeting and described this to them. They said their chemist claims the product breaks carbon bonds. Anyway, I'm just saying the overnight soak method is worth a try with this stuff.

Very interesting Keith. How much below maximum case length do you prefer to trim your cases? 0.002”, 0.003”, 0.005” or more? I’m starting to believe that I have over trimmed (as recommended in just about every reloading manual) my Lapua 308 Winchester cases 0.010” under maximum case length. Not many experienced shooters mention it but I have heard one experienced shooter say that trimming cases 0.005” below maximum case length is enough. Cheers 🍻

I wonder....if one were to polish the neck area...like down to 1-3 micron would reduce or eliminate rings? It most likely is more about temperature and welding carbon to the metal.

This topic has been stopping me from opening my freebore up on my .260 Remington to allow seating my bullets at the boat tail and the neck.

A very hard substance is correct like one of the hardest things in the world.

I'm waiting until mine turn into diamond.

Precisely why I always clean my rifles after shooting them, whether 3 shots or 20. It won't have a chance to build up.

So , clean the barrel and don't worry about it , got you .

🤣I used to 300-800 rounds between cleanings, I mostly did it out of guilt. Recently, I picked up about 50ft/sec pressure out of nowhere. I did not check for a carbon ring but I assumed I had the dreaded carbon ring. I used a battery drill, short cleaning rod and a nylon brush with boretech carbon remover. My speed went straight back to normal.

Try a product called helmar 5700 carbon remover - won't work with scrubbing - it needs to soak for a fair while 6-8 hours you can follow up with wet patches during that time. Dry patch it out and give it a sweets or co2 boretech clean with a new brush It will remove all carbon and copper without using issio or jb /abrasives with risk of polishing the bore 👍👍

clr works good if you let things get away from you

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CLR with a nylon brush works great. Quit panicking, read the label. "Designed to work without damage to surrounding metal" i know they meant sinks, coffee pots etc. but my stuff is fine.

The carbon ring can coat the freebore area. I changed bullet brands on my M1 Garand and they would not chamber. Yes, a lot of bronze brushes fixed it.

What if you had a cast of the chamber neck to measure, or use the reamer specs. Then turned a brass rod with teeth to make a carbon reamer?

What about a copper brush on a short aluminum rod on a cordless drill.

You forgot uneven tire wear.

Step 1. Buy a chamber gauge and figure out your max case length. Sinclair makes them Step 2. STOP trimming your brass till you know this number in step 1. It’s ok to trim so all cases are the same but then stop. Step 3. Trim to .005 off max. Not the book max. Not the book recommended trim length. But the max of your actual chamber. Enjoy 😉

Use freeall everytime you clean. And clean every session, hmmm about

His rifles dont have any carbon rings because he's already sold them off as "Winning in the Wedding" diamond rings 😅

It sounded like you just gave me an excuse to buy a decent sized ultrasonic cleaner?

Much more critical for 22lr since the lead is so soft and can be deformed

Do AR-15's ever get carbon rings?

My carbon rings gave me diabetes.

Clickbait arrows? Really!

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