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watkins666

Nitride Barrel treatment

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Hi one and all. Does anyone have any experience of Nitride Barrel treatment ? Does anyone in the UK do this ?

 

Many thanks

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I looked into this myself for both barrels and actions/bolts.

Nitriding (or tufftriding as its known outside the US) is quite a specialised process for firearms. It's all dependant on the metallurgy of the materials you want processing. Is it chrome moly, SS, pre hardened or not? Seems that nitriding works best for chrome moly. It'll work with SS but if it's pre hardened it can affect the hardness of the material after processing.

 

A big concern for nitriding is the temperatures at which it's done. I've been told by Defiance in the US to not exceed 900 degrees f for their SS actions because they're prehardened. If you have a different material, you might get away with a higher temp. Because of the temps, all hinging on the metallurgy, you must find someone who knows exactly what they're doing. I did speak to Keighley Laboratories Ltd about Nitride QPQ but their temps are too high. In the end I ended up asking Defiance to send the action to H&M metal processing to get it done there in the US before it gets shipped to me. H&M do all the Nitriding for Glock, H&K, Smith & Wesson, LWRC etc, so they're specialists in doing it for firearms. They also spoke to Defiance about the special makeup of their actions, so again, they're able to tailor the temps and length of time to do the proper job and not ruin the integrity of the action.

 

I think AI in the uk get some of their stuff Tufftrided but I don't know who does it for them.

 

One thing to consider is that a barrel must be fully finished BEFORE going off to Nitriding. So it's got to be chambered, threads cut, fluted, proofed...whatever you want to do, AND run in (around 100 rounds then fully cleaned spotlesslessly) as the Nitriding process makes the material so tough, you can't do any of that gunsmithing afterwards. Because the barrel must be fully finished, you may need to ensure the processor has a license to handle firearms parts...otherwise they may not ba able to touch it legally. Don't quote me on the ins and outs of the law there though.

 

Hope that helps - good luck with finding a specialist in the UK. If you do, let me know!

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I've not spoken to either of those companies you mention but having a quick glance at their websites suggests they might not be suitable because of the methods they use, or rather don't use.

As I understand it, there are several methods to 'Nitriding'. The proper salt-bath nitriding (Liquid Salt Bath Ferritic Nitrocarburizing ) process is the one that is really required for the likes of barrels/actions etc. It is a quench, polish and quench process (QPQ) or some variation there of. The articles I've read suggest that plasma and gas nitriding aren't suitable because the temperatures are too low to impart the level of hardening necessary to resist the wear shooters are looking for on the metal parts in question.

 

Here are some helpful articles worth reading on the subject:

 

https://sites.google.com/site/freeballisticcalculator/black-nitride-melonite-and-qpq

 

http://docslide.us/documents/practical-nitriding-and-ferritic-nitrocarburizing-d-pye-asm-2003-ww.html

 

http://www.blacknitride.com/whatis.html

 

https://www.shootingillustrated.com/articles/2015/8/26/finishing-touches/

 

http://bulletin.accurateshooter.com/2010/09/salt-bath-nitriding-for-barrels-whidden-is-impressed/

 

http://bulletin.accurateshooter.com/2009/02/melonite-surface-treatment-for-barrels-bolts-and-actions/

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Worth speaking to them. However the temperature they list (580 degrees c) or (1076 degrees f) sounds like it might be just a bit too hot. I've read you shouldn't go above 900f if your material is pre-hardened SS.

Again, it all depends on the specific material your barrel is made up of and if it's been pre hardened or not.

 

I'd chat them through what you want to do and if they're any good/sensible, they'll ask for a detailed spec sheet of the metallurgy makeup of the barrel material to ensure their process won't compromise the core strength. Ask your barrel maker for this.

Again, I did just this with Keighley Labs but passing the details of the Defiance action makeup to their metallurgist, they felt their process was too hot.

But it's worth speaking to hauckht and see what they say.

 

Good luck!

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Many thanks for the input. I am surprised that looking at the possible benefits regarding extended barrel life that no body provides the service in the the UK.

 

Many years ago, Malcolm Cooper at AI came up with the idea that nitriding stainless barrels would give extended life and all the barrels for a particular order were nitrided inside and out. However, the hard nitride skin was very brittle and started to flake off the inside of the barrel - probably due to thermal stresses. The result was a shorter barrel life, not a longer one. Needless to say, the idea was dropped pretty quick.

 

You see the same with hammer forged barrels - particularly Tikka barrels for some reason. The work-hardened skin on the inside of the barrel starts to flake away after just a few hundred rounds.

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Sorry to strongly disagree but it is completely untrue that hammer forged barrels have a hardened skin in the bore, just as it is completely untrue that it starts to flake away at any time let alone, as you state, "after a few hundred  rounds". Cold hammer forged barrels coin the material down through its full thickness onto a tungsten carbide mandrel with the male form of the rifling which it then takes up. The best hammer forged barrels, like ours, are consecutively honed on vertical three spindle honing machines to a Grade 1 finish prior to forging. We have produced large quantities of our barrels and Parker Hale, who owned the forges before we acquired them, produced hundreds of thousands. Graham who was in charge of that division at Parker Hale confirms there was never any such problem and I also confirm that to be the case with all those we have made in the past 10 years since we recommissioned the plant at our Bampton facility. Our barrels outlast all other production methods, typically a .308 having an accurate life endurance of between 12,000 and 14,000 rounds. 

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Buster, are you talking Armalon barrels?

Could you define accurate life - Sub MOA, Half MOA etc?

Thank you

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