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Gas Nitride Barrel finish

3650 Views 21 Replies 10 Participants Last post by  MickeyC
Terra, is there any chance of being able to buy a barrel with a Gas Nitride treated bore as opposed to chrome lined?
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Probably not. I don't think we even have a vendor who would do that for us. Why do you ask?
It produces a finish as tough as chrome but with the smoothness of Stainless steel. So you get accuracy and longevity.
sounds interesting... I can bring it up with the engineers & Alex.
Thanks, it should be worth considering.
sounds interesting... I can bring it up with the engineers & Alex.
Before distracting Alex from finishing my XCR-M, keep in mind the benefits of Nitride are dubious and only applicable with VERY specific types of metal, heat treatment time and temp, and gas type. Its a very inconsistant process which, and requires a lot of overhead to get, which is partly why the 556 is known as being a 2MOA to a 6 MOA gun. Irregularties in barrels = spotty accuracy. On machine tools nitriding works great because precision isnt a concern. Hell, I'm convinced only Swissarms is anal enough to mass produce nitride barrels and get it right.

Also, corrosion resistance is determined by testing, not a process. Nitride has the potential to be slightly more corrosion and abrasion resistant than chrome, but the only way to find out is to abuse a batch of barrels. Obviously with chrome we know what we are getting, and the standards industry wide are very good.
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Any treatment sucks if you do it wrong. SwissArms barrels are known for being very accurate and bench shooting of the 556 and 55x series has shown accuracy being much better than 2-6 MOA. Perhaps the people you shoot with should practise a little more.

As for Chrome lining, it is an industry norm and massively available and that is why it is popular. That doesn't mean it is the best.

"Corrosion resistance" of a substance is down to chemistry and quality of application of that substance over a surface. If you want to get technical, then at least research for more than five minutes and try to get it right.
Hey MickeyC, with the chrome lining you have get your reamers and such milled to compensate for the extra material that'll be added later with the chrome. Is it the same with the gas nitride? Honestly, chrome lining or the stellite in the old M60 barrels is the only coating I've ever heard of.
Is it the same with the gas nitride?
Carbonitriding requires nothing to compensate for dimensions - it's a surface treatment OF the steel, not something on top of the steel.
Typically, the claimed 'build up' is less than 1 micron.

Imagine a surface hardening process - that's really what these are. The same treatment that they do to some parts for jet turbine impellors (I can't imagine a hotter, more errosive environment!) to make 'em last.

Another good example is the cyanonitriding that hardens the Glock slides.

Mickey - I found the Daw's phone number, but still trying to dig through notes to find the rest. Sorry for the delay..... had to go through the gas mask annual course since the last time we spoke, it's thrown me a bit behind.

The military was looking at doing this treatment INSTEAD of chrome lining on M4 carbines. The thing is, changes are slow. Last I talked to my buddy, he said they had 18,000 rounds through one of the test M4s - all 30 round mag dumps. No errosion of the throat to date.

Me? I was looking at it for another reason entirely...... my 6.5X55 is a true long-range stick. I run the velocities up significantly (I backed off a touch from 3000 fps, using 142 grainers) but it comes at a price. For the last couple of years, it's been a safe queen 'cause I haven't had the 'extra' cash to have her rebarrelled :-\
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Help me out, what problem are we trying to solve here?
If that's case then some of the exotic calibers or wildcats could benefit from it since they're typically just done up on a CrMo barrel. Is there a vendor that offers this?
Gr8 - the problem we're solving (in my personal situation) is limiting barrel throat erosion. For others, it's a matter of getting the benefit of chrome lining, without the detracting problems.

M118 - that's the contention. That's why I was looking at it. If you're OK with sending in your barrel / barrelled action and waiting until they get a batch, it's moderately priced. About what it cost me to have my barrel cryo treated (which was moderately cheap). If you want it done NOW, they'll do it NOW, but charge you for the whole batch price instead of just a small portion of the batch price.
Ouch. Maybe we should get a group thing going or something?
Imagine Stainless Steel accuracy with chrome lined longevity. That is what we are after.

Bravo, no worries mate. When ever you get around to it is fine. My Lapua shoots 300 grain SMKs at 2800 fps and if i'm lucky the barel lasts 2500 rounds.

Chrome lining is hard but it is also uneven and thus not good for accuracy. The nitride process delivers a smooth finish.
If y'all put a group buy together, I'd be interested.

Especially if I get my 6.5 barrel <g>

Apparently POF utilizes this process on their P-308 rifles to achieve their "relentless reliability". If I may quote from the April '08 Guns and Weapons mag...

"The P308’s barrel is a real breakthrough in small arms technology. The barrel and barrel extension is heat treated by a “deep nitride heat treatment” which case hardens the barrel. While Frank is understandably reluctant to divulge the exact nature of the process, the results are obvious. The treatment penetrates the barrel steel to a depth of three-to five-thousandths of an inch and gives a surface hardness of Rockwell 68-72. Hard chrome has a surface hardness of Rockwell 65-68, but there are issues with hard chrome that make it less than ideal for rifle barrels, primarily that hard chrome has surface irregularities that cannot be eliminated, which is the primary reason that match rifle barrels are almost universally plain chrome-molybdenum steel. POF’s deep nitride treatment, on the other hand, has zero imperfections and is incredibly smooth. For this reason, P308 barrels are regularly achieving amazing accuracy that literally has to be seen to be believed. We’ll discuss this at length below. The deep nitride process also virtually eliminates fouling of any kind, copper included."

I can't personally attest to the accuracy or validity of these statements, but I thought you guys would find it interesting.
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That's why i'd like to see it offered. Accuracy and longevity.
When a barrel is nitrided, is the whole thing (bore and exterior) or just the bore treated? Also is it possible to nitride stainless steel or just chome-moly?

While we are looking into nitrided XCR barrels, how about using a 1:7 twist and Wylde chambers to maximize the accuracy potential please?
The entire thing is treated, inside and out.

Yes, it works on stainless as well.

Maximize accuracy potential? I can hit easily out past the range where my ammo goes from really effective to marginal performance. How would that help?

I don't own a 1:7 twist 5.56. The fast twist was used to stabilize heavies. Heavies were designed to give better terminal performance in military theaters.

Since I'm not limited personally by the Hague accord, I run highly terminal lightweight bullets, and forget all the other stuff.
Bravo, what "highly terminal lightweight bullets" do you run. Handloads?
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