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Thread: Bolt life question.

  1. #81
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    Quote Originally Posted by constructor View Post
    The company that carburizies the bolts and carriers we machine brings the core of both up to apx 50 for maximium toughness of the parts. I'm not saying what our exterior is but those 2 parts can be either to hard and brittle or not hard enough.
    I've seen some bolts on the market that are so hard they chip at the edges around the cam pin hole and I've seen another brand that (I believe are 8620) are so soft that the lugs compressed. I have cut a carrier from that same company in half with a $9 hacksaw, I'm not sure it was tempered at all.
    I would like to see some company Melonite a bolt to see how it holds up ...in their own rifle.
    You offer NC DI bolts? If so any feedback so far on expected lifespan?

    And for what it's worth, I had my HK416 bolt NC-QPQ treated so i'll be able to give a sample of 1 feedback as time progresses.

    So far it's got just under a thousand rounds through it with virtually no visible wear. I know that means nothing for microscopic fatigue cracks that may be forming though.
    It is missing the point to think that the martial art is solely in cutting a man down; it is in killing evil. It is in the strategem of killing the evil of one man and giving life to ten thousand -Yagyu Munemori

  2. #82
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    Quote Originally Posted by GrumpyM4 View Post
    You offer NC DI bolts? If so any feedback so far on expected lifespan?

    And for what it's worth, I had my HK416 bolt NC-QPQ treated so i'll be able to give a sample of 1 feedback as time progresses.

    So far it's got just under a thousand rounds through it with virtually no visible wear. I know that means nothing for microscopic fatigue cracks that may be forming though.
    We haven't made any in the last year but will get back to it after the move.
    Are you taking a completely raw bolt and just having in melonite treated as the ONLY heat treat or was the bolt carburized to begin with by HK and then Melonite treated?

    The bolts and carriers we machine are carburized first and then melonite treated or we have had some TIN and TiAlN coated after being heat treated.
    I've talked to 2 different companies that heat treat material for us using different processes both have told me Melonite is a quick process so the core never makes it to 10 points under the surface hardness if the material is .125 thick. If it is a very thin piece like a saw blade or an automatic transmission steel then the core will gain depending on the thickness of the material.
    I drill though hundreds of Melonite QPQ treated barrels a month, after the surface is broken with a carbide bit the rest of the material is very soft just like cutting through a normal stainless or parkerized CM barrel.
    AR15performance
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    The 6.8 is the best choice for hunting deer and hogs with an AR15.

  3. #83
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    Quote Originally Posted by constructor View Post
    We haven't made any in the last year but will get back to it after the move.
    Are you taking a completely raw bolt and just having in melonite treated as the ONLY heat treat or was the bolt carburized to begin with by HK and then Melonite treated?
    To be honest, I have no idea how HK treats or processes their bolts. I would assume they have some sort of heat treat process, otherwise their products wouldn't last like they do.

    I had one of my HK bolts QPQ nitrided after the fact on top of whatever it was HK did.



    The bolts and carriers we machine are carburized first and then melonite treated or we have had some TIN and TiAlN coated after being heat treated.
    Any feedback on the carburized/nitrided bolts regarding bolt life, etc.?

    I've talked to 2 different companies that heat treat material for us using different processes both have told me Melonite is a quick process so the core never makes it to 10 points under the surface hardness if the material is .125 thick. If it is a very thin piece like a saw blade or an automatic transmission steel then the core will gain depending on the thickness of the material.
    I drill though hundreds of Melonite QPQ treated barrels a month, after the surface is broken with a carbide bit the rest of the material is very soft just like cutting through a normal stainless or parkerized CM barrel.
    I am aware of the limitations of straight nitriding, which is why I commented on that in my convo with Bill about having a good CH process under nitriding would prevent any possible cracks in nitriding from spreading further.

    I would never think it a good idea to forgo CH in favor of straight nitriding.
    It is missing the point to think that the martial art is solely in cutting a man down; it is in killing evil. It is in the strategem of killing the evil of one man and giving life to ten thousand -Yagyu Munemori

  4. #84
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    Quote Originally Posted by GrumpyM4 View Post
    To be honest, I have no idea how HK treats or processes their bolts. I would assume they have some sort of heat treat process, otherwise their products wouldn't last like they do.

    I had one of my HK bolts QPQ nitrided after the fact on top of whatever it was HK did.





    Any feedback on the carburized/nitrided bolts regarding bolt life, etc.?



    I am aware of the limitations of straight nitriding, which is why I commented on that in my convo with Bill about having a good CH process under nitriding would prevent any possible cracks in nitriding from spreading further.

    I would never think it a good idea to forgo CH in favor of straight nitriding.
    I don't know about the bolt life we have never had one break.
    Agree, carburize first melonite after.
    AR15performance
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    The 6.8 is the best choice for hunting deer and hogs with an AR15.

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  6. #86
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    What effect does nickel content have on work hardening and reduction in fatigue life?
    Black River Tactical
    BRT OPTIMUM HFCL Barrels - Hammer Forged Chrome Lined 11.5", 12.5", 14.5"
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  7. #87
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    Bill,

    The reason Grumpy is so intent on this line of questioning, is he had his HK- MR556 bolt QPQ'd a couple months ago before you made your post yesterday. He is kind of stuck with the results at thsi point.
    My brother saw Deliverance and bought a Bow. I saw Deliverance and bought an AR-15.

  8. #88
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    Quote Originally Posted by Bill Alexander View Post
    Now that's funny!
    Looks like someone jumped both feet in before understanding the complexity of their decision.
    Last edited by E-man930; 06-11-12 at 16:31.

  9. #89
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    Sorry if this has been mentioned already in this thread.

    Is there any good data or user experience with JP'S ENHANCED BOLTS?

    Can't seem to find any long-term or short-term experiences on these. I see some early threads in the '09 time frame of folks that have them, but nothing recent with how they've performed for them.

    Found something on ARFCOM about them not being what they used to be - that the supplier changed and now it's all marketing fluff or something.
    Last edited by Brahmzy; 06-11-12 at 17:44.

  10. #90
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    nvm didnt see the bolt part
    Last edited by sinlessorrow; 06-11-12 at 17:48.

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