Nitride treated bolts and barrel extensions.

[constructor]

Is there anyone here that works in a lab or company(one that does not Nitride parts) that can check the hardness of material?
I already know the answer but it' more like I need it verified by someone not connected to any company that Nitrides parts but is involved in the firearm community and interested in the truth.
I can send a few Nitride treated barrel extensions. I do not think I have any Nitride treated bolts but I'll check.
My suspicion is Nitride treatment of parts that have already been hardened to 60C by carburizing anneals the parts to the point that the lugs of barrel extensions and bolts compress under the impact and headspace increases as a result.
I have already talked to a couple of companies that nitride parts and of course they say Nitride treatment does not soften the parts and also does not change the torque of barrel extensions installed on barrels. I've been installing barrel extensions and re-torquing barrel extensions for 12 years.
I've also read on forums over the years that Nitride treament causes the parts to become brittle due to hydrogen infusion. from the testing I have done that is not true. The parts are softer not more brittle.

[Hkbeltfed]

Nothing to offer, except your post reminded me of this thread...
https://www.m4carbine.net/showthread.php?149149-Barrel-extension-wear-FYI

[constructor]

Thanks, forgot about that one. I stopped using melonite treated extensions several years ago. IMO barrels and carriers are fine, bolts and extensions that are subject to impact are not.
The top photo in that thread shows what I am seeing also. It depends on the bolt thrust generated by the cartridge diameter and pressure of the cartridge, 5.56 will be the least effected, 6.8 more and Grendel even more so due to area x PSI.

[MegademiC]

I may be able to perform hardness. Let me do some digging, but it would take a while. I could do 15T scale, but what you want may be too hard for us to test, and Id have to wait till Im at another facility.

From my non-working knowledge of nitriding, hydrogen embrittlement is a non issue as no hydrogen is generated by the process. I thought it was a molten NaCN or KCN bath.

[constructor]

I may be able to perform hardness. Let me do some digging, but it would take a while. I could do 15T scale, but what you want may be too hard for us to test, and Id have to wait till Im at another facility.

From my non-working knowledge of nitriding, hydrogen embrittlement is a non issue as no hydrogen is generated by the process. I thought it was a molten NaCN or KCN bath.

The bolts and extensions should be in 58-62C range with a core in the mid 50s. I believe since the sections are so thin it must be tested HB then converted to "C".
Companies selling the Nitride treatment are telling me one thing but what I am seeing is completely different. They all say Nitride treatment will not effect the torque of an extension on a barrel. Wrong ... found that in 2008 see the link to the video. I can hold a new barrel in my hand and just blip an impact and the extension screws right off.

https://www.youtube.com/watch?v=1msz7zW8S5U&feature=youtu.be

The next thing they say is Nitride treatment only knocks down the hardness 1-2 pts. Again what I see is a much softer material dropping more like 8-10 points.

[MistWolf]

To get real data, you'll need to measure hardness before and after treatment.

[Todd.K]

I have measured extensions to be softer after nitride. C scale.

I did not cut a sample to get a core hardness. Surface hardness and depth were variables I would have liked to control but did not.

[constructor]

To get real data, you'll need to measure hardness before and after treatment.

I have several hundred extensions that have not been nitride treated.

[MQ105]

Companies selling the Nitride treatment are telling me one thing but what I am seeing is completely different. They all say Nitride treatment will not effect the torque of an extension on a barrel. Wrong ... found that in 2008 see the link to the video. I can hold a new barrel in my hand and just blip an impact and the extension screws right off.



Doesn't it depend on whether the extension and barrel are treated as a unit vs treated separately, then assembled/torqued?

[Clint]

Yup.
.
.

Doesn't it depend on whether the extension and barrel are treated as a unit vs treated separately, then assembled/torqued?

[constructor]

Doesn't it depend on whether the extension and barrel are treated as a unit vs treated separately, then assembled/torqued?

Sure if there is no extension on the barrel there is no extension to come loose. If it is installed after treatment then the treatment doesn't effect it.

[markderp]

Is there any new information and processes for nitriding barrel extensions now in 2023? There are several high end manufacturers that use nitride barrel extensions. Are they just modifying the process/temp to ensure a proper rockwell or would the nitride still lower hardness to a measureable degree

[MegademiC]

I have a vickers hardness tester now.

I can also section parts for internal micro-hardness.

[markderp]

Have you tested any nitride parts with it yet? Bolts or BE's

[MegademiC]

Have you tested any nitride parts with it yet? Bolts or BE's

When I say "I" i mean the company I work for and have access to. Only low carbon steels at this point

[markderp]

Got it. I'd offer up a part for testing but the only nitride I have currently is on the barrel extension of the most expensive barrel I own. ...Or at least I think it's nitride....could be black oxide.

[constructor]

Is there any new information and processes for nitriding barrel extensions now in 2023? There are several high end manufacturers that use nitride barrel extensions. Are they just modifying the process/temp to ensure a proper rockwell or would the nitride still lower hardness to a measureable degree

A Nitride treated barrel extension came off a PSA barrel, on the hide April 4th.