Cleaning the carbon ring out of your chamber’s neck?

I am surprised you would see that much carbon build up.

If you are applying any type of mechanical cleaning on a reg basis with solvent, it will come out. It's not like a ceramic coating. Try Barnes CR10 as a very high ammonia does wonders on carbon too.

JB is wonderful stuff and does a really good job. You do not need anything more agressive then that. I would avoid any type of metal wool.

I think the more likely problem is thickening or thick case necks... do you outside neck turn often?

Have you confirmed clearance after bullet release?

You didn't say what chamber you are working with

Jerry
 
Mystic Precision said:
I am surprised you would see that much carbon build up.

If you are applying any type of mechanical cleaning on a reg basis with solvent, it will come out. It's not like a ceramic coating. Try Barnes CR10 as a very high ammonia does wonders on carbon too.

JB is wonderful stuff and does a really good job. You do not need anything more agressive then that. I would avoid any type of metal wool.

I think the more likely problem is thickening or thick case necks... do you outside neck turn often?

Have you confirmed clearance after bullet release?

You didn't say what chamber you are working with

Jerry
Click to expand...

I went 300 or so rounds with out cleaning. Accuracy never fall off. I didn't realize I had a problem until I started getting vertical spread at longer ranges. (this rifle typically holds under 1/2min vertical) At that point I checked with my chrono and found out I was getting a large velocity spread.

I do not neck turn.

The chamber is 260 rem and the rifle is a factory Tikka sporter.

On my fired cases 90% of the neck measures 0.297" and the very end measures 0.293 - 0.292". A sized case with a bullet seated is 0.292"

About 3/4 of my fired cases are tight enough to hold a bullet.

Thanks for the help.
 
BINGO... I can assume you are using Lapua brass?

Outside neck turn to 11 min... 12 thou max. Problem will go away and LR tuning will improve.

The front of the case should be even with the back of the neck or a bit LARGER. A bullet should fall freely into a fired case.

This is the number 1 problem we see with precision shooters and reloads. First question I ask is if the bullet will fall freely into the case... the vast majority will report no with similar results as you. Outside neck turn... problem dissappears

I am not saying cleaning is not important... it is BUT it is far less important then some will practise. however, case necks thicken with every firing. The sharper the shoulder, the less this happens.

With the 260Rem, I would expect growth of up to 1.5 thou with higher pressure loads. One firing, all is well... next firing... flyers all over the place and maybe even pressure sign.

I outside neck turn my brass almost every firing.... There is no such thing as no turn in precision shooting if you shoot your brass several times.

Jerry
 
Mystic Precision said:
BINGO... I can assume you are using Lapua brass?

Outside neck turn to 11 min... 12 thou max. Problem will go away and LR tuning will improve.

The front of the case should be even with the back of the neck or a bit LARGER. A bullet should fall freely into a fired case.

This is the number 1 problem we see with precision shooters and reloads. First question I ask is if the bullet will fall freely into the case... the vast majority will report no with similar results as you. Outside neck turn... problem dissappears

I am not saying cleaning is not important... it is BUT it is far less important then some will practise. however, case necks thicken with every firing. The sharper the shoulder, the less this happens.

With the 260Rem, I would expect growth of up to 1.5 thou with higher pressure loads. One firing, all is well... next firing... flyers all over the place and maybe even pressure sign.

I outside neck turn my brass almost every firing.... There is no such thing as no turn in precision shooting if you shoot your brass several times.

Jerry
Click to expand...

Yep lapua brass. After 6 firings my necks measure 0.013 - 0.0125.

While neck turning will give me more clearance for the time being I don't think it will solve my issue for good.



I guess I was hoping that someone had figured out a really good way to clean the chamber. Looks like I will have to clean a little more often and scrub the neck with a larger then caliber brush each time I clean.
 
As you know, I have shot alot and burnt up dozens of barrels. I have never seen nor experienced the carbon build up in my throat.

I do trim my brass... I outside neck turn religiously. Done. What you are describing is text book brass with necks too thick for the clearance in the chamber.

Go study the SAAMI drawings of your chamber. The vast majority of brass manf WHEN these chambers were certified were in the 10 to 11 thou thick. THICK brass was 12. Nowadays, 14 to 15 thou is not uncommon with certain brand of brass.

The reamers have not changed and all that needed clearance is eaten up by the thick brass you use.... not a good combo.

Given how stiff that Lapua brass is (assume you haven't started annealing?), thinner IS better. Turn to 11 thou (10 is also not too thin) and you might just find accuracy improve. Anneal properly to maintain that level of performance.

The crud should be visible to the naked eye if enough deposit to cause an issue. Best to take the barrel off the action and look but a bright flashlight may be all you need.

If there is any real carbon deposit, JB Reg or Bore brite WILL get it out. Another is Iosso but I have not used it myself. I think you are fretting about something that isn't a problem.

The solution is far more obvious.

Jerry
 
Mystic Precision said:
As you know, I have shot alot and burnt up dozens of barrels. I have never seen nor experienced the carbon build up in my throat.

I do trim my brass... I outside neck turn religiously. Done. What you are describing is text book brass with necks too thick for the clearance in the chamber.

Go study the SAAMI drawings of your chamber. The vast majority of brass manf WHEN these chambers were certified were in the 10 to 11 thou thick. THICK brass was 12. Nowadays, 14 to 15 thou is not uncommon with certain brand of brass.

The reamers have not changed and all that needed clearance is eaten up by the thick brass you use.... not a good combo.

Given how stiff that Lapua brass is (assume you haven't started annealing?), thinner IS better. Turn to 11 thou (10 is also not too thin) and you might just find accuracy improve. Anneal properly to maintain that level of performance.

The crud should be visible to the naked eye if enough deposit to cause an issue. Best to take the barrel off the action and look but a bright flashlight may be all you need.

If there is any real carbon deposit, JB Reg or Bore brite WILL get it out. Another is Iosso but I have not used it myself. I think you are fretting about something that isn't a problem.

The solution is far more obvious.

Jerry
Click to expand...

I will get back to you after I try firing it. I did clean my chamber and I will see if that did the trick.

Like you said neck turning is a good idea but it will have to wait. I went a little overboard on my 338LM project.
 
I have read about quite a few issues with carbon build up and extreme powders, I assume you are using H4350 or something similar? The little bit that stays at the edge of the neck in the chamber doesn't affect the pressures the way that the carbon in the throat will. I can almost guarantee that if you have a good ring built up at the end of the chamber then you have a good build up through the throat and lands. I fought this a lot with Varget in a 308, I'll pay a ttention to your findings since I'm about to start the journey with a 260.
 
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dusticles said:
^^^This! The little bit that stays at the edge of the neck in the chamber doesn't affect the pressures the way that the carbon in the throat will. I can almost guarantee that if you have a good ring built up at the end of the chamber then you have a good build up through the throat and lands
Click to expand...

If might if the brass can't move away from the bullet.

I did a pretty intense bore cleaning job first because I figured that was the problem. I got most of the carbon out. There's still a healthy amount of copper in there though.

Tomorrow I will see if my chamber cleaning job with a brush on a drill did anything.
 
if you have some spare time and want to see and know whats going on try this.

take a new piece of brass and seat a bullet down past the shoulder junction and measure the neck from the bottom to the top for diameter and concentricity, then do this with a piece of sized brass that you have shot a half a dozen times, you will see what is going on and realize that it is time to neck turn in order to get things back to where they need to be to shrink the groups.......

lapua brass already has a tendency to be thicker in the necks then it needs to be, but that is their spec and if you get a reamer build to lapua brass your okay, in a factory chamber such as yours I am willing to bet that it is spec'd out to Remington brass dimensions, much thinner then lapua's.

I have run just shy of 6000 rounds through a barrel without ever cleaning it, accuracy didn't slowly fall off and pressure signs just didn't appear at the next range visit, but what did happen was the barrel was like shooting a laser, factory brass reloaded 10 or 12 times, annealed maybe 3 times, next trip to the range a month later and all of a sudden 5 inch groups at 100 yards, why do barrels die like that???

bottom line is this............you need to turn your necks, your not getting that much carbon in your barrel........ever.......
 
I have a 260rem reamer here that was made to saami spec as far as I know..., and neck is .300" dia on it. Reloaded ammo is around .294" with my lapua brass, never neck turned anything. Perfect clearance...
I highly doubt any factory chamber uses a tighter spec, seems they're usually on the sloppy side if anything, but never hurts to give it a proper cleaning, make sure brass is to the right length after sizing and see what happens.
A bit more neck clearance doesn't hurt anyhow.
I use N160 in my 260rem, great stuff.

Btw where the neck ramps down to throat/bullet diameter, its not a square shoulder/corner, it has a slight angle(supposed to anyway), I think its usually around 45° some may be a bit steeper but still no issues for a brush to get in there and clean it out easily.
 
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SAAMI and CIP allow for variations in all dimensions of the reamer. Factories can and will regrind reamers. Was the reamer used to make the rifle in question min spec? Was the reamer even dimensionally correct?

The only way to know what you have is to measure it directly.

or indirectly by dropping a bullet into a fired neck. If there is clearance, the case neck will expand and resistance on a bullet will be ZERO. If a bullet cannot freely fall into a fired case, the clearance is simply too small for the components in question.

Jerry
 
So I have a pretty big update. I didn't get a chance to try out my gun but I did find some brass that I shot in my rifle from shot 1 - 10.

Its factory Federal Premium ammo that I used for brake in before I got dies. When I measured the brass it has a taper on the neck and the bullets don't fall easily into the fired cases.

I also more carefully measured the neck wall thickness. The Lapua stuff is 0.0145 per side and the Federal is 0.0125 per side.


What do you guys figure? Is there something wrong with my chamber?

I didn't have problems until I was on my 6th loading. Do I need to anneal?

Edit: I will be buying the stuff I need to neck turn and hopefully anneal as well.
 
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http://www.sharpshootr.com/carb-out/
 
It is not uncommon for a bullet not to slide back into a fired case. Necks expand to fit the chamber, but if the clearances are not excessive often the brass springs back... enough that the end of the brass lightly grips a bullet. This is where you need to know chamber dimensions...
 
Mystic Precision said:
As you know, I have shot alot and burnt up dozens of barrels. I have never seen nor experienced the carbon build up in my throat.

I do trim my brass... I outside neck turn religiously. Done. What you are describing is text book brass with necks too thick for the clearance in the chamber.

Go study the SAAMI drawings of your chamber. The vast majority of brass manf WHEN these chambers were certified were in the 10 to 11 thou thick. THICK brass was 12. Nowadays, 14 to 15 thou is not uncommon with certain brand of brass.

The reamers have not changed and all that needed clearance is eaten up by the thick brass you use.... not a good combo.

Given how stiff that Lapua brass is (assume you haven't started annealing?), thinner IS better. Turn to 11 thou (10 is also not too thin) and you might just find accuracy improve. Anneal properly to maintain that level of performance.

The crud should be visible to the naked eye if enough deposit to cause an issue. Best to take the barrel off the action and look but a bright flashlight may be all you need.

If there is any real carbon deposit, JB Reg or Bore brite WILL get it out. Another is Iosso but I have not used it myself. I think you are fretting about something that isn't a problem.

The solution is far more obvious.

Jerry
Click to expand...

Great post,I just learned something I had no idea about.As a side question, Jerry,how do you aneal your brass? More correctly what steps do you use and what indicator of temp do you use?
 
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