Carbon donut
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Carbon donut
Hello everyone
last week i had some trouble chambering a round on my 7th or 8th shot in my second stage, upon inspection there were marks engraved on the projectile and a carbon ring just in front of where the case mouth sits in the chamber, which shocked me because i scrubed it clean the day before.
when i got home i scrubbed it clean once again using jb in the throat and got it spotless, i verified using a bore scope and it was bare metal.
today on a totally clean barrel using the same load as before i had a practice shoot at 100 yards firing 11 shots with no issues but at the 400 yard mound halfway during my first stage it had trouble chambering a round once again with the same scoring around the projectile as before which has left me stumped as to how quick the donut is forming. i dont mind cleaning but the donut is forming far to fast. any one have any ideas?
some info on the rifle
barnard action
bartlein light palma barrel 11 twist chambered in .308 throated for hbc's done about 1150 rounds
my load is 46.4 grains of 2208
lapua brass
federal gold medal match large rifle primer
155 gr hbc 15 thou jump
tl;dr
carbon ring forming extremely fast need some help getting it under control
thanks all
last week i had some trouble chambering a round on my 7th or 8th shot in my second stage, upon inspection there were marks engraved on the projectile and a carbon ring just in front of where the case mouth sits in the chamber, which shocked me because i scrubed it clean the day before.
when i got home i scrubbed it clean once again using jb in the throat and got it spotless, i verified using a bore scope and it was bare metal.
today on a totally clean barrel using the same load as before i had a practice shoot at 100 yards firing 11 shots with no issues but at the 400 yard mound halfway during my first stage it had trouble chambering a round once again with the same scoring around the projectile as before which has left me stumped as to how quick the donut is forming. i dont mind cleaning but the donut is forming far to fast. any one have any ideas?
some info on the rifle
barnard action
bartlein light palma barrel 11 twist chambered in .308 throated for hbc's done about 1150 rounds
my load is 46.4 grains of 2208
lapua brass
federal gold medal match large rifle primer
155 gr hbc 15 thou jump
tl;dr
carbon ring forming extremely fast need some help getting it under control
thanks all
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Re: Carbon donut
personal preference but i always found 2208 dirty and 2206H a lot cleaner in my rifle
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Re: Carbon donut
john h wrote:personal preference but i always found 2208 dirty and 2206H a lot cleaner in my rifle
I can shoot 200 rounds or more with 08 and have no issues. If this issue is happening it is not powder it is something else. resizing, loading or the armourer at fault no way can a carbon ring cause issues that quick something else is wrong.
Chris
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Re: Carbon donut
Do you have an ogive to base measuring tool? If not get one. I measure every round I make/ Also a carbon ring wont stop you chambering a round have you trimmer your brass recently for example something else is going on it is not the carbon.
Chris
Chris
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Re: Carbon donut
http://forum.accurateshooter.com/thread ... .3772542/j
Have we identified what carbon and where yet lads ??
Mr Boyer's book talks about a carbon ring at the front of the chamber that can be a problem. This build up ( assuming it does exist ) will only be removed properly with a special tool used in a certain way ?
Have we identified what carbon and where yet lads ??
Mr Boyer's book talks about a carbon ring at the front of the chamber that can be a problem. This build up ( assuming it does exist ) will only be removed properly with a special tool used in a certain way ?
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Re: Carbon donut
Boyer's book BTW is very good and explains a lot of shooting details very well. I would totally recommend it.
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Re: Carbon donut
You need to drop the "j" of the end of that link to stop the good old 404 error.
Yes Tony Boyer's book is a gem.
I have used many brands of powders over the years - Norma, VV, Nobels, Alliant, ADI, WW and the only time I got caught out with a carbon ring was several years ago with Winchester 760 in my old 6.5 Swede Ackley. After about 200 shots from new I had resistance chambering the round (at a championship shoot!). Coincidentally the day b4 the shoot my Hawkeye had turned up and I had it with me and “lo and behold wot’s this". Pretty tenacious to remove - short stroke cleaning the JBs. Never had the problem again as I just ensured I paid attention to that part of the chamber on a more regular basis. W760 has a deserved reputation for carbon rings but 2208??
I agree with Pommy Chris, something else may be going on, but cannot offer further constructive comment.
Yes Tony Boyer's book is a gem.
I have used many brands of powders over the years - Norma, VV, Nobels, Alliant, ADI, WW and the only time I got caught out with a carbon ring was several years ago with Winchester 760 in my old 6.5 Swede Ackley. After about 200 shots from new I had resistance chambering the round (at a championship shoot!). Coincidentally the day b4 the shoot my Hawkeye had turned up and I had it with me and “lo and behold wot’s this". Pretty tenacious to remove - short stroke cleaning the JBs. Never had the problem again as I just ensured I paid attention to that part of the chamber on a more regular basis. W760 has a deserved reputation for carbon rings but 2208??
I agree with Pommy Chris, something else may be going on, but cannot offer further constructive comment.
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Re: Carbon donut
Pommy Chris wrote:Do you have an ogive to base measuring tool? If not get one. I measure every round I make/ Also a carbon ring wont stop you chambering a round have you trimmer your brass recently for example something else is going on it is not the carbon.
Chris
I measured all my rounds and they are all within a thou of each other and the cases have not grown significantly warrant trimming, i can put an empty case in the chamber and the bolt falls closed so its not fouling on the case but the projectile. I will take a picture of the marks left on the projectile.
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Re: Carbon donut
These are the marks being left on the projectile. I colored it in with sharpie so you could see it better.
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Re: Carbon donut
What was the reamer used for that chamber and what freebore?
Looks like a hard jam to me.
Looks like a hard jam to me.
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Re: Carbon donut
Longranger wrote:What was the reamer used for that chamber and what freebore?
Looks like a hard jam to me.
im unsure what reamer was used when it was smithed i specified that i would be using hbc projectiles but it looks like it has more freebore and a tighter chamber then a b150
i thought it was a hard jam also but the marks on the bullet are to far down and around the entire circumference and when clean has no effect on closing the bolt
i will have to take some pictures now it clean
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Re: Carbon donut
Mr Sako
Have you measured the bearing surface OD of your projectiles . Most throat dia are .30845 (but it depends on your reamer specs) it could be possible that your projectiles are larger in diameter than your throating reamer diameter.
Depending on quality of projectiles some maybe ok others that are larger may not?
I dont believe it's a carbon ring problem
Cheers
Alan
Have you measured the bearing surface OD of your projectiles . Most throat dia are .30845 (but it depends on your reamer specs) it could be possible that your projectiles are larger in diameter than your throating reamer diameter.
Depending on quality of projectiles some maybe ok others that are larger may not?
I dont believe it's a carbon ring problem
Cheers
Alan
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Re: Carbon donut
Wal86 wrote:Mr Sako
Have you measured the bearing surface OD of your projectiles . Most throat dia are .30845 (but it depends on your reamer specs) it could be possible that your projectiles are larger in diameter..
I dont believe it's a carbon ring problem
Cheers
Alan
Alan
I to thought it had something to do bearing surface diameter but i loaded up a dummy round with a sierra palma and a berger fullbore with the same issue
attached are some pictures of the chamber cleaned
thanks
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Re: Carbon donut
I would clean the rifle make rounds for a shoot and remove firing pin and chamber every round. Then do your shoot and see what happens. No way is that carbon causing those marks on the projectile.
Chris
Chris
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Re: Carbon donut
Pommy Chris wrote:I would clean the rifle make rounds for a shoot and remove firing pin and chamber every round. Then do your shoot and see what happens. No way is that carbon causing those marks on the projectile.
Chris
Its clean now and all 24 round chambered with no markings. Ill see what it does on saturday.
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