Help: Is this a carbon ring?

mrjashu

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Jan 18, 2017
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65
Hi Folks,
This is a continuation (adding more information) of this thread that didn't get much traffic. Hopefully moving over to this forum and the additional pictures will help.

A buddy gave me an old hunting rifle to work on his reloads for him. He had been running the same load for years but it suddenly stopped shooting good. Also the velocity went through the roof. He thought maybe powder lot or bullet lot changes might have been the problem. I shot it a little bit with some very light loads (according to the book) and pressure was bad right from the start. I did a light cleaning on the rifle, patches only no brushing.

So is this a carbon ring, and possibly the source of the pressure issue?
1.jpg
2.jpg
3.jpg
 

aushunter1

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Nov 16, 2012
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Australia
Doesn't look like anyone is willing to post so I will give it a shot(pun intended).

While I cant diagnose from the pictures I would do 2 things, give the thing a dam good clean with a brass brush & good copper & carbon solvent.

Re check all the screws & bolts for torque, scope, bases ,action.

Shoot it again with known load & see what happens.

Another problem could very well be throat erosion & just normal barrel wear.

Barrels do not last forever!!
 

26Reload

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Dec 25, 2016
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SE Idaho
I would say yes to the carbon ring.....but I don't think its bad enough to cause your problems....the leade(?) tl the lands looks built up a touch...i would bet the barrel doesn't look any better......scrub it clean and start throwing bullets..se what happens.......before and after...2020-01-20-16-42-02.jpg2020-01-22-20-09-28.jpg
 

Gunpowder

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Jun 16, 2003
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Location
Nebraska
If I'm seeing it correctly it looks like a lot of carbon built up right in front of the mouth of the case in the chamber. It would explain the higher pressure if it's pinching the mouth of the case, sort of like a forced crimp. I'd like to hear how others scrub that out as I've had that issue. I used jb on a brush one size up from bore size but it's a pain in the butt.
 

new2mud

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May 3, 2010
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Heart of TX
Nope. Looks to be the transition from chamber to rifling from the machining. Actually, it does not look bad.
From Rick’s observation it appears that darker section is smoother and lower-lying than the rest, as it appears to start raising where the fire cracking is forming (on the right). If indeed that darker area is in fact raised (and the picture is misleading), then perhaps it is carbon build up.

See Rick—I’m learning from you.
 

Rick Richard

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Jan 7, 2014
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North Carolina
Too straight are even edges for it to be a carbon ring in my opinion. Not to say the dark area may be some discoloration due to carbon, but not a carbon ring.
 

pawater

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Dec 18, 2012
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820
I agree with the above, it could be the start of one. Or maybe just slight carbon discoloration. How many firings on the brass? Maybe trim length? I would clean it good with a bronze brush and solvent. Then patch until clean. If the barrel were shot out, I would think it would not shoot well, but I don't think it would cause pressure.
 

25WSM

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Oct 17, 2011
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New Castle PA
Looks to be the start of one for sure. That's where the carbon ring forms. Get it clean now before it's an issue. On most factory Chambers there is enough clearence to really never be a problem but if you turn necks and have .003 or less clearence then it can be an issue much quicker. Guys that shoot br use a tool that is a shorter rod with a handle bent into it like a car Jack that twist. Use one size brush bigger than the bore and run it up in the neck and turn the brush. It really helps to put a very wet patch with carbon remover up in that spot over night. Once you get it clean it's easy to keep it clean by doing the brush twist Everytime you clean.
Shep
 

freddiej

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Aug 10, 2010
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537
Location
Carson City, NV
MrJashu, it sure looks like the case mouth/lead transition. it also look like carbon build up around the case mouth. a good bronze brush will help this with BoreTech C4 carbon remover. scrub it in a circular motion with the bore brush.
 

Bang4theBuck

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Nov 19, 2013
Messages
383
You might check the overall length of the brass. Sometimes if it gets a little long, and there is the start of a carbon ring (which is what I see), then the case neck can become compressed by the carbon ring, even if the necks arent long. Use the same device you used to take the picture and slide it down from the muzzle end. position it in the same spot and chamber an empty piece of brass. You will be able to see if it is pushing into that dark ring area, or further. May or may not be your issue. Keep us posted.
 

mrjashu

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Jan 18, 2017
Messages
65
Thanks for the responses everyone, I'll talk to my buddy about scrubbing it out and let you know how it goes!
 

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