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Thread: Nitride Treated Barrels?

  1. #51
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    Quote Originally Posted by Littlelebowski View Post
    Just because a barrel's chrome lined, does not mean it's inaccurate or less accurate per se than a steel barrel.. My old FN SPR shoots (sold it to a friend) right around .25 MOA with FGMM.
    Agreed. It's just much more difficult to do. FN has had issues with their chrome lining but when it adheres their rifles are very, very accurate and exceedingly durable (and less maintenance intensive). I think the nitrocarburization offers a better solution - more corrosion resistant (depending on difusion layer depth, etc.) and no geometry changes. The M249 chrome spec is "twice the thickness called for on the M16" so that could be interesting. Now I'm sure that is what FN is doing for the SPR. How well do they maintain concentricity? I don't know. John Noveske claims 2/10 thousandths for his chromoly barrels with thick chrome linining which is Match Grade. I have a *feeling* that FN is doing similar for their bolt guns.

  2. #52
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    Is there a company that will nitrate a barrel for me?
    Or is it like chrome lining were you have to place a large order?

  3. #53
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    Quote Originally Posted by dewatters View Post
    The 1968 report is a summary of the available technology and emerging research in barrel construction for automatic weapons.

    Materials for Small-Arms Gun Barrels
    I happened to have that sent to me in an email yesterday. It states that chrome lining is superior to nitriding for barrel life purposes.

    I also found a few other papers that were related.

    There was a study done with 5.56 LMG barrels. The barrels were shot at a rate of 200 rounds per minute, to failure. Rejection criteria was a velocity loss of 200fps or 20% of rounds yawing 15 degrees. The bare CMV barrels were rejected between 2500 and 12000 rounds. The nitrided CMV barrels lasted 30,000 rounds, on average. Stellite lined, chrome plated CMV barrels went 40,000 rounds. They didn't have plain old chrome lined CMV barrels.

    All barrels were rejected for velocity loss, BTW.

    More details on my blog at vuurwapenblog.com.

  4. #54
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    Stellite lining is different than plain chromelining, so the above may not be apple to apple on 30k vs. 40k rounds. Stellite lining is used in M2 50cal to extend barrel longevity.
    Last edited by Bushmaster-M4A3; 11-22-09 at 21:18.

  5. #55
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    Quote Originally Posted by Bushmaster-M4A3 View Post
    Stellite lining is different than plain chromelining, so the above may not be apple to apple on 30k vs. 40k rounds. Stellite lining is used in M2 50cal to extend barrel longevity.
    Yeah, I know, that's why I said they didn't have data on plain jane CMV chrome lined barrels.

    The other study indicated that the chrome lined barrels still had an edge for longevity.

  6. #56
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    Lastest technical articles show nitrocarburization to be more wear resistant than hard chrome. It's also more corrosion resistant, too. This is as I initially thought and explains why Accuracy International, Sig (and presumably H&K on the G-Series rifles) use this on their rifle barrels. I will soon know about Sako, too, as I think I have access (or can gain access) to a "worn out barrel". Now to find an interested Metallurgy/Material Science professor at LSU or access to the Metallurgy Lab at Southern University.
    Last edited by Mjolnir; 11-22-09 at 21:34.

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    Quote Originally Posted by Mjolnir View Post
    Lastest technical articles show nitrocarburization to be more wear resistant than hard chrome. It's also more corrosion resistant, too. This is as I initially thought and explains why Accuracy International, Sig (and presumably H&K on the G-Series rifles) use this on their rifle barrels. I will soon know about Sako, too, as I think I have access (or can gain access) to a "worn out barrel". Now to find an interested Metallurgy/Material Science professor at LSU or access to the Metallurgy Lab at Southern University.
    I would like to see this data, because it directly contradicts the studies I've seen. It may be more wear resistant in certain applications, but rifle barrels are not drill bits.

    I would also like to know more about the thickness of the hard chrome used in the test. I do electroless nickel plating in my garage. According to a company that does nitrocarburization, QPQ has about 4 times the corrosion resistance of nickel (which has slightly more corrosion resistance than hard chrome). But they didn't specify the thickness of the nickel plate. I know that I can get 1/4 mil to rust pretty quickly. However, I can't get 2 mils to rust. But I could get my QPQ'd Glock slide to rust.
    Last edited by 87GN; 11-22-09 at 21:44.

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    Don't compare a Stellite lined throat with any other kind of barrel. Stellite is some serious stuff for a MG barrel but I suspect the juncture 1/3rd of the way up the bore would not be conducive to good, rifle-like accuracy.

    MG's don't have groups, they have 'Beaten Zones'!

    BTW, M-60's had Stellite liners.
    My brother saw Deliverance and bought a Bow. I saw Deliverance and bought an AR-15.

  9. #59
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    Quote Originally Posted by Mjolnir View Post
    Lastest technical articles show nitrocarburization to be more wear resistant than hard chrome. It's also more corrosion resistant, too. This is as I initially thought and explains why Accuracy International, Sig (and presumably H&K on the G-Series rifles) use this on their rifle barrels. I will soon know about Sako, too, as I think I have access (or can gain access) to a "worn out barrel". Now to find an interested Metallurgy/Material Science professor at LSU or access to the Metallurgy Lab at Southern University.
    If you were up near Detroit I could probably help. I am a metallurgy student with access to a lab and possible SEM access.

  10. #60
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    Quote Originally Posted by ggt1_02 View Post
    If you were up near Detroit I could probably help. I am a metallurgy student with access to a lab and possible SEM access.
    I was in the Detroit Metro Area but I found it prudent to vacate the Auto Industry prior to the "total meltdown". In many respects I wish I was still there as I'd have easy access to the equipment.

    I'll be back up there in the Spring, let's have a Honey Brown Ale. Meet at The Firing Line in Westland.

    Kevin-

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