Gunsmithing Carbon buildup on crown vs. accuracy?

[Rprecision]

How does carbon buildup on the crown affect accuracy?

Particularly with braked and even more so with suppressed rifles I am finding a significant build up of carbon.

Are there any tips or tricks to cleaning the crown without risk of damage?

What say you?

 

[MarinePMI]

Brake cleaner/carburetor cleaner always seems to work.

 

[Rookie]

I was just told by my gunsmith who is setting my barrel back that the buildup on my crown from suppressed shooting may be affecting accuracy. His recommendation was fine steel wool and brake/carb cleaner.

 

[Bugholes]

I try to soak it with with a foaming carb cleaner or other non-evaporating aggressive cleaner- then brush with a toothbrush. This keeps buildup down but it always still looks stained. Depending on the angles used in your crown (I do a lot of 90 degree under brakes/suppressors), fingernail, credit card, or plastic scraper works better than you might think.

Back to the original question, I find it hard to believe that the buildup of carbon in its natural blast pattern on the crown would get to a level that it would affect accuracy- let's face it, it will never obstruct the bore or get in the way of the bullet path. In the case of a timed brake the brake is massively disrupting the blast pattern anyway

 

[Killswitch Engage]

if it gets real bad i chuck it up in my lathe and knock of .050 lol

 

[Graham]

Muzzles are self-cleaning, regardless of caliber.

 

[varmint slayer]

Still shoots under .5 moa with ease. More like 1/3. Never cleaned and never will.

 

[jbell]

I don't think buildup of carbon will cause a problem, where I have seen accuracy loss is after I clean my bore and some of the carbon comes off in big chunks. Which leaves clean areas and heavily carboned areas on the muzzle. I have seen accuracy problems after this occurred. I cleaned the whole muzzle and the accuracy was back. So when shooting suppressed or with a brake I just keep it clean with solvent on a rag. Sometimes I need to scrape it off and use my finger nail or a plastic scraper you could also use a razor blade if you are careful, depending on the shape of your muzzle.

 

[LRI]

Prestone A-freeze in a soup pot over a hot plate makes for a good fix.

You can make a nice broth if you throw your can in it as well. Cars go 100's of K's with no concern. Your suppressor will be just fine too.

 

[Killswitch Engage]

not sure i see the signifigance of antifreeze on carbon build up. it was never designed to attack that or protect from it. sounds like a interesting experiment.

i have had good luck with sea foam spray. it was designed specifically to break down carbon deposits and works quite well.

 

[dakor]

I use GM top Engine cleaner on my brakes and it works great.

 

[Rprecision]

I don't think buildup of carbon will cause a problem, where I have seen accuracy loss is after I clean my bore and some of the carbon comes off in big chunks. Which leaves clean areas and heavily carboned areas on the muzzle. I have seen accuracy problems after this occurred. I cleaned the whole muzzle and the accuracy was back. So when shooting suppressed or with a brake I just keep it clean with solvent on a rag. Sometimes I need to scrape it off and use my finger nail or a plastic scraper you could also use a razor blade if you are careful, depending on the shape of your muzzle.

This seems consistent with what I have seen, which made me curious how others deal with the problem. It's one thing on short action stuff but pushing 80 grains of powder through a can it can really build up on the muzzle.

Prestone A-freeze in a soup pot over a hot plate makes for a good fix.

You can make a nice broth if you throw your can in it as well. Cars go 100's of K's with no concern. Your suppressor will be just fine too.

Now this has my curiosity peaked. How does this work ? I didn't realize antifreeze attacks carbon.

I use GM top Engine cleaner on my brakes and it works great.

That's a idea I should have thought off. I even have some of that.

Still shoots under .5 moa with ease. More like 1/3. Never cleaned and never will.

You bring up a curious point. It seems like either the crown gets completely cleaned or like your approach don't touch it. At least with both it stays consistent, although your method is a lot less work.

 

[varmint slayer]

Prestone A-freeze in a soup pot over a hot plate makes for a good fix.

You can make a nice broth if you throw your can in it as well. Cars go 100's of K's with no concern. Your suppressor will be just fine too.

I remember you telling about using boiling antifreeze to clean carbon from muzzle brakes and thought about trying it on my can. I wonder how long a guy would have to boil it to see any worthy results. May have to give this a try.

 

[LRI]

not sure i see the signifigance of antifreeze on carbon build up. it was never designed to attack that or protect from it. sounds like a interesting experiment.

i have had good luck with sea foam spray. it was designed specifically to break down carbon deposits and works quite well.

I've been dinking around with RC airplane stuff for a long time. Giant scale 3D on gasoline and some pylon planes that burn nitro. The nitro (aka slimer) motors will cake up with a varnish from the castor oil in the fuel. A dark brown/black residue. It cooks onto the head and the tuned pipes. It's near impossible to remove the discoloration. A guy who's been doing this stuff since the 70s showed me this trick and it works beyond any expectation I'd of imagined.

I don't profess to know the chemistry. I just know that my $700 Jett and my rare quickie 500 Nelson 40 engines were brought back to "as new" condition by doing this and it doesn't hurt a thing.


c.

 

[Killswitch Engage]

cool. gonna have to give it a try

 

[Rprecision]

I've been dinking around with RC airplane stuff for a long time. Giant scale 3D on gasoline and some pylon planes that burn nitro. The nitro (aka slimer) motors will cake up with a varnish from the castor oil in the fuel. A dark brown/black residue. It cooks onto the head and the tuned pipes. It's near impossible to remove the discoloration. A guy who's been doing this stuff since the 70s showed me this trick and it works beyond any expectation I'd of imagined.

I don't profess to know the chemistry. I just know that my $700 Jett and my rare quickie 500 Nelson 40 engines were brought back to "as new" condition by doing this and it doesn't hurt a thing.


c.

So I am assuming you are using a full concentration and not mixing up with water.

When you say boil are you bringing the coolant to a full boil then dropping in your parts?

 

[ridgeway]

The new GM top cleaner is garbage. If you can find the older stuff, it works. Bore tech carbon cleaner works pretty good.

I find that a crown with a smooth finish cleans up very easy. I cut with a sharp HSS bit at high speed. Makes a real nice finish...