Carbon Build-up causing curved necks on fired brass?

R

RAG2

Guest
I just noticed on my varmint plinker (a 223AI) that the end of the necks are bowed in from the rest of the neck on my fired cases; it's visibly noticable. So either the brass is springing more at the ends of the neck, or possibly I have carbon build-up. I don't have a bore scope. The brass has been through a couple barrels, so it's far from new. Any thoughts?

I was thinking I'd go work the neck/throat area with a little Iosso or JB.
 
My guess is that the brass is "growing" from improper sizing and is too long for the chamber. This can be dangerous. Check your chamber length and you'll probably fix the problem by trimming your necks back.

THEN, if you so choose you may try to keep your brass from growing in length. Many never take this step, instead just living with the growth and trimming their necks allatime.....altho this will in turn lead to ANOTHER problem over time. That of casehead separation.

hth

al
 
The chamber length is a minimum of 1.772 (or maybe it's 1.776...from the reamer print) and depending on the lot of brass (I have a thousand pieces in three lots for this gun...Lapua and two different lots of Winchester), I have trimmed all to 1.750 or 1.760 and no pieces had grown more than .006...I was in fact trimming the brass today since I was stuck at home. So length shouldn't have been a problem, but somewhere in my boxes I also have a stainless chamber length gauge/insert that you seat in the brass...so I'll have to double check.

Al, how do I keep it from stretching...do you have a die recommendation? I just have standard RCBS FL dies that I continue to use because they actually throw very little runout.

Lawrence, I do think it's carbon, though I'm not sure...so I guess it's time I invest in bore scope. I've just never had this problem before, not even other rifles that have been shooting the same lots of powder and hade twice as many rounds through them.

THANK YOU!
 
I read an old article my Jim Carstensen where he stated he thought dies with expander balls were partially to blame for case stretching. I've never done a side-by-side comparison on the same rifle/brass to see if there is a difference, I don't know what to think on this.
 
RAG2,

you keep cases from stretching by achieving proper die fit and setup. Custom-fitted sizing dies exist for ONE reason, to give you a sizing apparatus which properly fits your chamber.

Buying off the shelf dies is like buying your shoes mail-order.......... some folks are perfectly served by that.

Some aren't.

I'm picky. I often have hundreds of dollars worth of my time involved in case prep. I believe that fit is crucial to shooting good aggregate scores. I have spent thousands of dollars on dies. I KNOW how to make dies work. I successfully maintain cases from PPC to 338 Lapua for many firings, as many firings as I want in fact. I've fired cases until the flashholes have eroded out of round.

This is a huge subject and will spark contentious debate but the simple fact remains that SOME of us can make cases last a long time if we so choose.

I do so choose.

al
 
I agree regarding dies I am a big believer...you've probably seen my recent post regarding the 20 TAC die and having a reamer custom-fit. I believe in good dies and good brass. This rig just so happens to have factory dies, but I recall they are actually a decent fit (on squeeze the body by about .002) and thus I never upgraded.

Thanks.
 
RAG2 said:
I agree regarding dies I am a big believer...you've probably seen my recent post regarding the 20 TAC die and having a reamer custom-fit. I believe in good dies and good brass. This rig just so happens to have factory dies, but I recall they are actually a decent fit (on squeeze the body by about .002) and thus I never upgraded.

Thanks.
Click to expand...

Oh I agree with factory dies, the cheaper the better, IF they do in fact fit. Sounds like yours do. If your dies are truly set up properly and your length is good then you just may have a carbon buildup. :)

al
 
that carbon ring from h__l

a carbon ring is HARD! after reading tony boyer's book, and using my hawkeye i was amazed! since there is a small(.010-.020 thous +) space in the chamber just in front of the case mouth, carbon deposits collect and after 2000+ degrees f and repeated firings it's amazing that diamonds don't form! if not removed and you use the sinclair chamber plugs to measure the length of your chamber, you can abut the plug against the ring and get a short measurement. mr boyer describes "stupid shots" as ones when the neck of a chambered round experiences a roll crimp into the bullet when the lip impinges the ring. he suggest a brass brush spun in the neck portion of the chamber to remove the baked-on carbon AFTER EVERY shooting session. i've using a synthetic brush made by hoppes. i think it is called TENEX. it's thick plastic. with a little jb and solvent spun on a rod using a black and decker variable drill it will come out but is resistent. if the ring remains and you shorten your brass, it's only time before you have the same problem. a borescope will absolutely identify the problem and it's removal. thanks.
 
For those that do not have bore scopes, if you carefully push a clean dry patch down the barrel from the muzzle to just in front of the chamber, with something that does not pierce it, and use a light, you will be amazed at how well you can see, with magnification. The patch acts as a reflector. without it, most of the light is not reflected back to the eye. Can also be done, from back to front, to better see the last couple of inches at the muzzle. The difference is significant.

Recently. I was doing some experimenting with different powders, that are dirtier than 133. On a second trip to the range, I did not get the results that I did the first time. After some thought, I decided that there might be a buildup of powder fouling at the front of the chamber. To make better contact with, and clean more aggressively in that area, I rubbed a small amount of gun oil, and then a small amount of JB, into a patch, and wrapped it around (slightly overhanging the front) one of my regular bronze 6mm brushes, that I had mounted on a chamber rod. This combination came to a very positive stop at the front of the neck part of the chamber, and it only took a few twists to clean out the fouling. I think that I probably will make up some patches with this combination, and keep them in a small container in my cleaning kit. I can see where I may have been missing something when shooting powders other than 133. In the past, with that powder, my chambers have not shown any carbon (using a friend's bore scope), after cleaning with my normal BBS, patches and brush method. Also, if we are not going to clean after every group, I think that it is particularly important to trim cases often, so that they do not have their mouths overhanging fouling at the front of the chamber.
 
I used to be in the habbit of employing the methods advised by Tony Boyer, but I got out of the habit I think. And 133 has spoiled me. This gun (the .223 AI) has had quite a bit of 133 put though it, but also a lot of Benchmark and even AA2200. Also, one more thing that just dawned on me...I purchased a couple different lots of Winchester brass and one batch was longer than the other...so I trimmed one batch to 1.750 and the other to 1.760; consequently, the carbon from the 1.750 brass may be crimping the 1.760 brass. Actually, the neck is sloppy, so I doubt it's crimping...but still not good and a lesson learned.
 
It's weird though...I have 6500 rounds through my tight neck 6BR with no carbon issues, and I've mostly used Benchmark, but a fair amount o 2200 and N133 too. At least I don't think I have any carbon issues...gun still pumps out sub .2s mostly. Maybe it's because all the brass is the same length...and there could possbily be a carbon "wall" just past where the brass stops, and it simply isn't affection anything at this time. With both guns, I probably clean once every 100 rounds, and usually every few hundred rounds I would plug the chamber and fill the bore with BBS overnight...I always hoped this would tackle the carbon for me. Geez...I need a borescope so I know what's goin on.
 
I've never done this but I would if I had no other option....... 10.00 worth of Cerrosafe gets you a chamber cast and then you can SEE what the end of the neck looks like.

al
 
lpreddick said:
a carbon ring is HARD! after reading tony boyer's book, and using my hawkeye i AFTER EVERY shooting session. i've using a synthetic brush made by hoppes. i think it is called TENEX. it's thick plastic. with a little jb and solvent spun on a rod using a black and decker variable drill it will come out but is resistent. if the ring remains and you shorten your brass, it's only time before you have the same problem. a borescope will absolutely identify the problem and it's removal. thanks.
Click to expand...

If your problem is in fact a carbon ring then the removal can be achieved with a carbon solvent like CTC or any equivalent.
Andy.
 
I recently did a test for products to "dissolve" carbon.
I took fired primers and used those and also the additional carbon that came from cleaning the primer pockets.
I used 6 products. 3 regular rifle cleaning products Butches, Boretech Eliminator and Wipe out with the accelerator.
2 automotive products made by Sea Foam and on hmmmm maybe it might work product called Goof Off.
I put 8 primers in a stainless steel cup and added a little of the carbon for good measure and let them soak for 30 minutes.
What I found was that none of the products had any effect whatsoever on any of the primers nor the loose carbon.

To say I was surprised is an understatement.
I got on the internet and started looking for a solvent that would "dissolve" carbon.
What I found in general on a lot of chemistry sites and others is that no normal solvents available to the public can actually "dissolve" carbon.
There were a lot of different but mostly concurring articles and posts on various sites that says carbon itself (like a diamond) cant just be dissolved.
It was explained that "carbon" in engines is also mixed with "gunk" and the mixture can be altered and moved out of the engine but that the same cleaners would not affect regular carbon....
It appears from one article that the carbon in our guns can only be removed by brushing and that some of the chemicals can help "break it up" but can not dissolve it.

Now I have to start all over and try the experiment and try a little minor brushing and see what might work with the least amount of work.
edit:
I will also try some more cleaners that were listed as possibilities.
 
The cerrosafe castings come out fairly pourous...so they would only reveal carbon if it's really bad...I think.

Regarding the "dissolving" of carbon...that makes sense. My guess is that products good at removing it, are simply loosening it (by chemical or abrasion)...but what do I know.
 
RAG You can make perfectly smooth and accurate castings with cerrosafe.
I do, but there is a key.
You need to warm the barrel if you dont they dont come out smooth.
 
Vern is right.

I guess I get sloppy in my assumptions sometimes, Cerrosafe being "pourous" did give me pause! :) I've always found a casting to show EVERYthing including the chambering/polishing/sanding marks in the chamber.

al
 
Vern said:
I recently did a test for products to "dissolve" carbon.
I took fired primers and used those and also the additional carbon that came from cleaning the primer pockets.
I used 6 products. 3 regular rifle cleaning products Butches, Boretech Eliminator and Wipe out with the accelerator.
2 automotive products made by Sea Foam and on hmmmm maybe it might work product called Goof Off.
I put 8 primers in a stainless steel cup and added a little of the carbon for good measure and let them soak for 30 minutes.
What I found was that none of the products had any effect whatsoever on any of the primers nor the loose carbon.

To say I was surprised is an understatement.
I got on the internet and started looking for a solvent that would "dissolve" carbon.
What I found in general on a lot of chemistry sites and others is that no normal solvents available to the public can actually "dissolve" carbon.
There were a lot of different but mostly concurring articles and posts on various sites that says carbon itself (like a diamond) cant just be dissolved.
It was explained that "carbon" in engines is also mixed with "gunk" and the mixture can be altered and moved out of the engine but that the same cleaners would not affect regular carbon....
It appears from one article that the carbon in our guns can only be removed by brushing and that some of the chemicals can help "break it up" but can not dissolve it.

Now I have to start all over and try the experiment and try a little minor brushing and see what might work with the least amount of work.
edit:
I will also try some more cleaners that were listed as possibilities.
Click to expand...

Ok don't believe me but I just disolved 1 gram of lamp black - pure carbon in 1 gram of CCl
4

Any other similar derivative compounds will also work.

Andy.
 
the "carbon" in a rifle barrel is totally different from lamp black. if you push a dry patch through a bore after 20 or more rounds fired you feel a roughness. this is powder residue obviously. the next bullet passing over this residue at 3500 fps and 4000+deg f produces tremendous compression...50.000+psi in the bore. how much pressure under the bullet...? the temp under the bullet...? this residue is transformed into a very hard compacted form of carbon. as noted "solvents", even if left for hours(i tried this) don't even start to "dissolve" the ceramicj-like, baked on stuff. microscopic abrasives (jb, iasso etc.) and a brass brush attack this stuff by physical means. the angle where the lands meet the groove seem to be the most difficult to get out. i am currently experimenting with a "chemical" approach that has promise. i don't know how this works, but i mix the pasty stuff of jb bore paste with a lemon scented home supply store ammonia and shake until cloudy, let sit overnight and it gels. add enough ammonia to get it to come out of a 4 0z bottle and use it after all powder residue is gone. the patches come out black with carbon from the grooves. after several patches, they are white and borescoping reveals a clean bore. it doesn't get copper very well but does get the carbon in the angle of land/groove. tried this combination with warthog copper remover but didn't gel...don't understand the chemistry but not questioning the results. haven't used a brush yet. witchcraft 101?
 
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