I'm going to be buying a 16" Rainer Arms UltraMatch SS barrel soon and wanted to make it black.

There are coating available obviously, but I was reading about ferritic nitrocarburizing (I've seen it mostly called Nitriding?)

I've read it really increases the specs of a barrel along with turning it black?

Can this be done on SS barrels?

Does anyone know more about this?

Does anyone know who I could send a barrel off to in order to have this done for a reasonable cost? (I know this is generally done in batches and don't mind having to wait in order to slip in a batch with a smith.)

It is also called QPQ and salt nitriding.  A company called NMI-TruTec specializes in it.  The contact guy is named Joel Kendrick.  If you go to 6mmbr.com you can look up the website and Joel's phone number and E-mail address.  They will do a single barrel.  It works on SS. If you bead blast the barrel you get a matte to semi-gloss outcome.  If you have a polished barrel  it comes out a very shiny black.
It doubles barrel life.

MMI-TruTec, email joelkndrck [at] aol.com, or call Joel at (704) 616-6442.

Are there different ways they do this process?  Salt, liquid bath etc?  Is one way better than the other?

Any idea how much this process costs on a 16" SS barrel?

I would prefer the matte black look in the end vs the shiny. But I'm not sure if RA UltraMatch barrel is already bead blasted for me.

If not that's obviously an extra cost, any idea on how much that is?  And can this Joel guy do that for me as well?

Doubling the barrel life sells this process. I just hope it's not outrageously expensive to have done.

Well I see that the UltraMatch line of barrels by RA do in fact come bead blasted already. Nice.

And I just read an article that said Nitriding is a $60 process?  If that's the case then I'm getting it done for sure.

Is it proper to get other things nitrided as well?  Gas block, bolt etc?  Or just the barrel?

Be aware that nitriding stainless supposedly reduces the corrosion resistance, whereas nitriding CM steels significantly increases corrosion resistance.  A nitrided CM barrel is much more corrosion resistant than either nitrided or bare stainless from the reports I have read, as well as being stronger.

Hmm yeah but I've been told that the accuracy of SS compared to CM is superior...

I'm in Ohio, so corrosion shouldn't be too much of a problem. (you are referring to corrosion from saltwater etc correct?)

Bump...

The accuracy of a particular barrel stems from more than just the composition of the metal used, it is in the machining of the metal and the ease with which the gunsmith can chamber,or the manufacturer rifle a barrel that matters most.  Many older shooters felt that CM was more accurate...

Spot on...

Keep in mind that ferritic nitrocarburizing (FNC) is a heat treating process (case hardening), not a metal coloring process. NiCorr, Tenifer and Melonite are all FNC processes that have been trademarked. Stainless steel cant be parkerized or nitrided effectively. Have someone paint it for you if you want it black.

Stainless has properties that make it inherently better for accuracy versus chrome moly. What effect having it nitrocarbided does to the accuracy though Im not sure.



OP, Coal Creek Armory is another company thats doing a version of the process as well.

I wasnt doing this process to just turn the barrel black, I was doing it because I heard it increases the barrel specs in an amazing way.  Its just a plus that it turns it black.  Hopefully it will be dark enough that I will like it & not have to worry about getting an actual coating done & save some cash.  If not maybe a cerakote or something will be what I chose.  

I def want to to the nitiriding.

I'm in Ohio, so corrosion shouldn't be too much of a problem. (you are referring to corrosion from saltwater etc correct?)

Well, it's corrosion (rust)... from water, humidity, fingerprints, etc etc.  Just look at the reports of people complaining about rusted M&P slides (example) for an example of the problem (M&Ps are nitrided stainless).

If I was planning on nitriding a barrel, I would get a 4140/4150/CMV steel barrel as the base.  After nitride you'll have a barrel that is much stronger, last longer, and more corrosion resistant than a stainless barrel, nitride or not.

hmm.  But how does the accuracy of the chrome molly barrels compare to a SS one?  I was told it gives you much more superior accuracy, thats why I was going to get the SS regardless if it was more expensive.

I was considering this one sold by Rainer Arms for a chrome moly:

http://www.rainierarms.com/?page=shop/detail&product_id=2277

But I'm not sure if its good for DPMS patterns?  doesnt say?  

For the SS option I was considering their Ultramatch series: (which is about $140 more expensive than the chrome moly Kaiser barrel so I assume the quality is much higher, even though the Kaiser quality is probably high as well)

http://www.rainierarms.com/?page=shop/detail&product_id=2338

Nitriding can significantly degrade the corrosion resistance of a stainless steel barrel, the degree to which depends on the alloy, the process, and the temperature.

You have to understand what nitriding is (whether salt bath, plasma, or gas). It is not a coating and it is not typically black. Many manufacturers apply a proprietary process to achieve a "black" color (a PVD overlay is a good example) but nitriding is a case hardening process that works by introducing Nitrogen to the surface layer of steel at a fairly high temperature (for stainless that is, not so much for carbon). It's similar to carburizing a Carpenter Tech 158 rifle bolt (actual mil-spec) to achieve a hardened surface layer but in the case of nitriding, it's Nitrogen that's introduced to change the surface composition, not Carbon. For a carbon barrel steel, 4140, 4150, 41V45, nitriding can be achieved at a low enough temperature so as not to impact the steel's temper, so it's affect on dimensional accuracy is minimized when performed correctly. 41V45 is particularly suitable since the added Vanadium is a strong Nitride forming element (along with Molybdenum––the "Moly" in Chrome-Moly steel).

The downside for a carbon steel rifle barrel of small caliber is that this process requires precision and experience. The temperature and time necessitated by each method, the uniformity of application, proper masking for parts not intended to be hardened, etc. all affect the final product. In addition, case depth can vary depending on technique/application and this clearly plays a significant role in the life expectancy of a treated barrel. A brittle surface can lead to spalling, and for a rifle barrel, this is deal breaker. So far, based on laboratory studies, it appears that correctly applied nitriding can better withstand the effect of hot gas errosion over chrome plate, but beyond this zone the benefit is negligible. The problem is, you better have your shit together when nitriding because the process occurs at temperatures and durations that can impact the temper and desired mechanical properties of the material.

Now, back to stainless, nitriding can provide a benefit in surface hardness, but it is usually done so at the expense of corrosion resistance. This depends on the alloy composition and application temperature though. Stainless steel is a "self healing" alloy in that the Chromium in the steel combines with Oxygen atoms (in the air) to form a layer called the Passive Film. If the film is scratched/disrupted, the Chromium oxides pack together and quickly reform the protective barrier that resists corrosion. However, nitriding requires a removal of those very same oxides (as well as a thorough degreasing, cleaning, etc.) and if applied at high temperature forms Chromium Nitride (CrN) which adversely affects the alloy's ability to resist corrosion. On the other hand, a properly applied plasma nitriding process can actually increase both wear resistance as well as corrosion resistance over the substrate alloy.

So what does all this mean? A barrel's accuracy potential is a combination of many factors, rifling type, rifling method, chamber, and precision machining all parts of the equation. And life expectancy is a different issue with new processes, coatings, and alloys challenging the traditional chrome plate process for the most durable solution. There is a trade off, depending on your priority, to achieve the best of both worlds. The trick for barrel makers is to combine both, to create the most accurate, wear resistant barrel available at a price acceptable relative to performance.

Ok so you think a plasma applied nitriding is better than a salt bath on SS barrels?

These are the two barrels I'm trying to decide on:

Rainer Arms Ultramatch SS barrel

Which I would then add a Plasma nitriding to I guess to get the best of both worlds in hardening & corrosion resistance

Or this Kaiser barrel that is also sold by Rainer Arms which is a Chrome/Moly and already Nitrided:

Kaiser 16"

The Kaiser is clearly a good bit less expensive, but Rainer guarantees sub-moa with their UM barrels.

What would you go with?  SS with Plasma Nitriding or 4140 Chrome Moly with Nitriding?

Depends on what you are building: a gun for precision shooting, or a fighting gun (decent accuracy, but you probably won't win any long range matches with it).  I assume you are looking for a .308 barrel.  If you can find one made of 410 stainless, you will have the best of both worlds.  The only 410 stainless barrels I have seen are in 5.56 though.  Would still like to see Daniel Defense make  a CHF .308 barrel - hey, a guy can dream can't he?

Get the Rainier UM SS barrel and forget the nitride, the UM barrels are made from Shilen match grade blanks and are some of the finest custom production barrels you can buy and it will last you a very long time with great accuracy. If you want the best you can buy then get it and don't look back but I wouldn't risk ruining a barrel that good with some metal treatment that might make it last a few more rounds at best. If anything I would call Shilen and ask them what they think of the process, they can tell you much more about why it would or would not be good for the barrel, not to mention it probably voids any guarantee of accuracy and anything else.

1811guy and EWP have given good advice.

As for your specific question, I would choose plasma over salt bath for stainless steel, but personally, I would not send a one-off barrel project to an outfit that offers nitriding unless I was absolutely sure of their experience, proven results, and if they were familiar with the barrel maker's material spec, heat treat, etc.

Besides, as was mentioned before, if I were Rainier and you nitrided one of my barrels, I would in no way feel obligated to honor my accuracy guarantee. And while a Rainier SS barrel might be capable of sub MOA accuracy, realistically, are you as a shooter? If raw accuracy is your goal, and you feel like you can take advantage of it, go with the Rainier. If you're waiting for zombies and this rifle barrel is the last one on earth, go with the Kaiser. If you want black stainless, send it off to be PVD coated (Ionbond) or hit it with some Krylon.

I am endorsing neither but making a rough guess as to where your head might be at!

I almost forgot to address this but that's maybe because my subconscious was screaming at me not to!

This is the age old debate; all things being equal, is a stainless barrel more accurate than one made from a chromoly steel?

Now opening can of worms....

Notice I said "all things being equal". There are many CM steel barrels that will out-shoot a 410 or 416R stainless stick. But unless you do the analysis, research, and testing, you can't rule out manufacturing, machining, process, and methodology variances that will naturally affect the results. A poorly manufactured stainless steel barrel can be junk no matter what the substrate.

Now, having qualified that, there are stainless alloys that simply have a much more uniform micro structure over carbon steel, better hot gas erosion resistance, and improved machinability (as well as polishing/lapping superiority) that make for a more accurate stick. Adding nitriding, chrome plate, and other longevity applications to the mix tends to change the dynamics as far as life span is concerned which may potentially affect accuracy.

Also, let me qualify my statements by disclosing that my company manufactures barrels from both mil-spec 11595E chromoly steel (CMV or 41V45) as well as a new breed of aerospace stainless steels. There are advanced coatings, applied at relatively low temperature, that compliment the substrate amazingly well. I cannot comment beyond this, but suffice it to say, barrel technology continues to evolve and nitriding's role in small arms development is yet to be solidified.

I missed these. "Stainless steel cant be ... nitrided effectively": This statement is simply not true. Stainless steel (whether austenitic, martensitic, ferritic, duplex or PH) can be successfully nitrided to improve both wear resistance as well as corrosion resistance over the base substrate, and beyond that of typical carbon steel. The key is application temperature to achieve the desired result. Much gets repeated on the internet as fact but the research is out there to confirm for yourself with just a bit of study.

ETA: The comment about being "stronger" from Gamma762 is misleading (Gamma, please don't take this as an attack––you and I had many good discussions back when about 1:8 twist CHF stainless barrels––I respect your contributions to the forum very much my friend, so much so that our stainless barrels are mostly all 1:8 CHF) as "strength" is an over used and misunderstood term as it relates to material science. Are we talking tensile strength or compressive strength? Believe me, it's easy to say "strength" without knowing it's a particular term used in metallurgy. Tensile strength is typically measured by pulling a specimen apart until it gives/fractures/fails/changes subject to specific force. While there is relevance to rifle barrels, most folks hear "stronger" and think "better" when the math is very different and specific.

Nitriding is old science, almost as old as stainless steel (90 to 100 years old), and is not the right choice for every application. There are many aerospace stainless steels that solve specific problems nitrided carbon steels do not.

How can an exterior finish make the barrel more accurate or last longer?  I am raising the flag on that remark.  Cerakote the exterior, it will last and won't corrode. Other than a chrome lining on a fighting gun I don't know of any coating that does anything for the bore.  The chrome lining is good for wear but is not often good for accuracy.

SBN infuses all surfaces with nitrogen, inside and out.  So the bore is treated as well as the outside of the barrel. The nitrogen basically binds anywhere oxygen would, so it can't.  It hardens the surface without dimensional change unlike chrome, so the barrel should be as accurate as it was before the treatment, assuming it was done correctly.

tag for later

Return your money 100% if your not happy, and SS, and Nitride all at the same time.
I took a chance! I cant tell you much, mines a few parts from shootable, but Iv asked around and found no issues

It may not be what you have planned 100%, but for the cost Try out the nitride for yourself, if you dont like it,  its because YOU dont like it, not because some SOB on the internet told you that you dont like it..
The photo of the nitride barrel at the bottom of the page, does look that good.

"Nitride Finish Upgrade: Case hardening processes which increases scuffing resistance, fatigue resistance, & corrosion resistance."




http://www.rainierarms.com/?page=shop/detail&product_id=2267




edit typo

wat?

Damnit!  I wish they had the nitrided finish when i ordered my select barrel.  it may not be an ultramatch SS but it is still very accurate