I have a BCM SS410 and I want to know how sending it somewhere (not sure where) to have it cerakoted will affect accuracy and barrel life. Will the cerakote finish ruin accuracy? will it make it any better? Will it increase barrel life? should I break this barrel in before or after the cerakote job?
Thanks in advance.

It's my impression that coatings like KG coat for example are applied to the exterior of the barrel, not the interior. I wouldn't think it would have any effect on life or accuracy.

AFAIK it can be applied to the outside exclusively or the inside and outside.

It will have no effect on barrel life or accuracy. It is applied to the exterior of the barrel only.

Just in case he didn't make it clear. Do NOT coat the inside of the barrel! At best, you've wasted money, at worst, you could potentially destroy the barrel and the rifle.

The only thing worth mentioning at this time is salt bath nitriding, otherwise known as Melonite or "Ion bond" as some dealers are calling it.  The biggest advocate right now is Rock Creek.  They claim the benefits in longevity are significant, with no affects on accuracy.

http://www.hefusa.net/index.htm

http://www.accurateshooter.net/Adverts/meloniteorderform.pdf


http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1673958&page=1

This is not practical for a barrel that has already had the gas port drilled and the barrel extension attached.



 

Why?

Because the barrel extension comes loose.

It is held on by the index pin.  

I don't understand.

Clearly.



 

Please explain. I am curious also.

Why be a dickhead?  I'm just asking the questions.

Denny and LaRue sell "ion bond" barrels. I'm just trying to understand the process.  Are their barrels really treated before threading and indexing?  I was under the impression machining was very difficult after the salt bath process.

And what is your point about the gas hole?  How is that different than the bore?

From the link posted by glock24:
http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1673958&page=1

Not exactly what the people in that thread think. The barrels do come loose, but they come loose from the extension - the barrel nut doesn't come loose. And it's not because it's "slick" - in fact Melonite is not very slick. It's because of the extreme heat required for the process (this causes dimensional changes and can also cause annealing in heat treated parts).
From DSA's foray into melonite:
http://www.ar15.com/forums/topic.html?b=2&f=319&t=188943


IonBond/DLC is not Melonite/Tenifer, IonBond uses lower temps for the process.
AR barrels can be successfully Melonited, this needs to happen before the barrel extension is attached (headspace is set) and the gas port drilled.
I know BCM's IonBond barrels are exterior only, I believe that goes for some other manufacturers, but not all. Rock Creek Melonited barrels are interior/exterior. Cerakote on a rifle barrel is mainly for cosmetic reasons. It is exterior only. It is far too thick for interior use and would exhibit massive and rapid wear if you somehow managed to "paint" the inside of a barrel anyway.
Oh, nice profanity laden IM glock24, maybe next time you should read the threads you post before telling people that "this is the only thing worth mentioning". Especially when you don't even know the difference between IonBond and Melonite. If I'm what you said because I was rude to you in response to your sheer ignorance, what are you for telling someone to have a process done to his barrel that will a) render it useless and b) cause a potentially dangerous situation to occur?
 

Your first reference makes no sense.  Is he talking about the barrel extension or the barrel itself?  If the barrel nut wasn't properly torqued, of course the barrel can work loose.  The same rules apply for any bolt action rifle barrel with Melonite treatment.  In fact it should be even worse on a bolt rifle because the barrel relies on torque alone to stay tight.

Your second reference appears to be a manufacturing problem.  The receiver index pin on the barrel extension is supposed to be drilled and driven deep enough to engage beyond the barrel threads, thus making the extension about impossible to remove.  I offer you this;

http://ar15barrels.com/making.shtml


Here the pin hole is drilled into the barrel and the pin pressed into place. The extension can not be removed after this.

Thanks for the additional information.  Was it really that hard to explain what you know rather than being rude to the folks who are still learning for themselves? I think my IM to you sums it up very accurately.

 You're right, I am a "fucking asshole."



But I'll never give someone advice that costs them hundreds of dollars in destroyed components because I don't understand what I'm talking about.





If you are "just learning for yourself," then don't tell people what they should or shouldn't do.





Stay in your lane.
 

I find it humorous that your knowledge of this situation comes out only after I response to your rudeness.  

Am I ignorant of bore coatings?   Of course I am. I learn a little bit more every day just how ignorant too.  That is why you won't read in my first post that I am an expert on this topic.  The fact that I said Melonite was "worth mentioning" is because I have read about it being used inside precision rifle barrels.  If the OP is going to pursue more information on bore coatings, this is my suggestion instead of Cerakote.

You on the other hand seem to know more about this topic than I, yet choose to provide only vague and sarcastic answers to the questions.  If I'm causing someone pain through my sheer ignorance, how does it feel to cause the same pain through sheer arrogance?

Almost thirty thousand posts, and you still don't know how to be courteous.  The sad thing is that after a few days, the details of this conversation will start to blur, but it will take only me seeing 87GN to remember that you were an asshole when you clearly didn't need to be.

Out of curiosity, about how many posts did it take before folks starting reading your sentence fragment sarcasm and then immediately kneel down to perform fellatio?  I need to know when I'm getting close.

In the best interest of the OP, it might be time to resume the big-boy talk;

1.  Assuming 87GN is accurate, it would appear that a Melonite coating needs to be applied before the barrel extension is installed. Does anyone know of a gunsmith that will do this?  Again, I'm not sure if threading, and drilling for the gas port and index pin is possible on Melonite coated steel. If not, I propose the following;

a.  Finish all barrel machining including the threads for the barrel extension
b.  Temporarily install the barrel extension, drill the blind hole for the index pin, and the through-hole for the gas port
c.  Remove the barrel extension and sent out only the barrel for Melonite treatment.
d.  Install an untreated barrel extension after coating.

To 87NG's point, this would only be possible on an existing barrel if removing the extension was practical.  Does anyone know if pulling or drilling out an installed index pin is practical?

Disclaimer:  I am not an AR-15 barrel manufacturer.  I am just an ignorant fool who likes to hang out in the technical forums

87GN is quite correct.

Melonite after the fact will cause the barrel extension and barrel to expand and contract at uneven rates and cause the barrel extension to become loose.
If the gas port has already been drilled… good luck to you.
And per the spec the index pin does NOT extend into the barrel as one would think.
The only thing holding the barrel extension on is the proper amount of torque.

If you want a Melonite treated barrel, buy one and sell the one you have.
It is simply not advisable to “retro-fit” the coating to a finished barrel.

I was short with you, but you are hardly innocent of the "rudeness" you so detest in me. You responded here and by IM with unnecessary insults. Unlike you, though, I was not "pained" by this. Welcome to the internet. You've only been here twice as long as I have. If using the word "clearly" is so injurious to your psyche, I suggest you seek counseling.
What you "suggest" is not possible. There is no "temporary" barrel extension attachment. Quality barrel manufacturers will attach the barrel extension after the finish process.
See my post on 5/7/2010, just slightly before your "response to (my) rudeness" brought out my "knowledge of the situation" - http://www.ar15.com/forums/topic.html?b=3&f=124&t=495986

And Adams Arms' response -

 While I don't think that melonite is the best for the barrel extension, they are approaching the situation from the right angle.
Which brings me back to the very first post I made in this thread:

 It's that simple.
The sooner you understand this, the sooner we can move on to arguing about other pointless crap.


 

Exactly.



And even if the OP were to purchase a BCM IonBond SS410 barrel, the inside of the bore would still be bare stainless steel.



Considering the performance of the BCM SS410 barrels, I wouldn't be concerned - nor would I want anyone messing with the way it came from BCM - especially on the inside.



 

How does the process effect the gas port?  The coating itself?  Just trying to get edumacated.

No issues with it affecting the gas port per se. Dimensional changes because of the differences in "chemistry" between the 8620 barrel extension and the (insert barrel steel here, none of which are 8620) result in the barrel extension coming loose.





 

It’s a matter of alignment.
The barrel extension is torqued and the indexing pin is installed, this is what determines the 12o’clock position, which is where the gas port is drilled.

If you torque the barrel extension, install the indexing pin, install the barrel in the drilling fixture that indexes the drill bit to engage the barrel perfectly at the 12o’clock position as it relates to the indexing pin….
Then heat the barrel and barrel extension to the point that they expand differently and come loose, you will then have to re-torque the barrel extension thereby throwing the gas port out of alignment…
This is something that can only be fixed by welding the gas port shut and re-drilling it to the new 12o’clock position as is determined by the position of the indexing pin.

And that isn’t exactly a cheap or desirable fix…

ok, gotcha... thanx guys.