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How do I anodize an AR15 lower receiver?

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  • How do I anodize an AR15 lower receiver?


    I don't have an anodizing kit yet, but I will certainly buy one if I can use it to anodize an AR15 lower receiver (7075-T6 aluminum alloy).

    I have been looking, but I have not been able to find out the details of how an AR15 lower receiver is anodized.

    I believe it is done according to MIL-A-8625; supposedly Type III class 2, with a thickness of 0.002 (includes both penetration and build-up).

    But what are the details?

    What kind of pretreatment, what kind of dye is used, how is it sealed, etc.?

    I would greatly appreciate if anyone could provide this information? Thank you.


  • #2
    Ok, I searched the forum (something I should have done first), and have found that a type II anodized coating is probably what I want.

    Is it possible to do this with the Caswell kit? Will the black dye that comes with the kit give me a color that will match a Bushmaster upper receiver? Thanks.



    • #3
      The kit would give you what you need to get the job done; it is for type II anodizing. As far as the black being an exact match I don't know exactly what your black part looks like, and depending on exactly how the part is anodized (there are plenty of influencing factors) it may yield various shades even with the same dye. I think a person who goes by fibergeek on this board is into the AR15's.

      The kit comes with instructions that will help answer your questions. You will need a lot more details than what I am going to tell you here. You can also get the instruction manual from Caswell's separately.

      A part that is already anodized must be stripped and anodized again. Stripping can be done with the stripper sold by Caswell's, or with lye. Depending on the existing texture of the part surface it may alter it enough you need to restore the texture before anodizing by polishing, bead blasting, etc. The part may need to be desmutted, and will need to be absolutely clean and free of any traces of oil or other surface contamination before anodizing.

      The anodizing dyes such as sold by Caswell’s are a special organic dye and work better (much better) than dyes that some beginners use, such as clothes dye.

      The part is sealed in steam and/or boiling water, and often nickel acetate (a sealing compound) is added.


      • #4
        This may sound odd coming from me, but...

        If you're only going to do one AR lower, and have no other interest in anodizing, you would be better off having it done commercially. It would be much less effort and expense.
        Avoid stripping away the existing anodize from the critical pin holes, they won't show anyway. Tell the anodizer that you want an exta thick Type II layer, 2 mils thick. A thick layer will avoid the metallic look inappropriate on ARs. If they insist on a "Type III" (hardcoat) layer then so be it. Avoid jet black dyeing if you can with Type III.

        There is a firearms refinisher in TX that does firearms grade anodizing, and they have a FFL so you can ship across state lines.

        (edited for spelling)


        • #5
          Hello everyone,

          Thanks for the replies.

          One problem I have is that right now I am in a foreign country where there is no easy access commercial anodizers.

          If the kit will work I'll buy it and have a friend send it to me.

          I may end up doing some upper receivers as well.

          I don't have any plans to go into business, but there may be more than one AR15 related part.

          So I really would like to get the details of how to do it if possible. Thanks.



          • #6
            Well if you say so.

            Indicating what foreign country would help, you have stuff to aquire and much to learn.

            Start by downloading the LCD instructions from Caswell's main Site (their free) You will have questions after you study them.


            • #7
              Hello Fibergeek,

              I've been living on the island of Mindanao in the southern Philippines.

              A friend of mine here is an excellent gunsmith, and he has a shop, and he's also part owner of a security agency here.

              He has a few older AR15s that he wants to refinish. He was going to try to sandblast and paint them.

              He would prefer to anodize them, but there's no anodizing shop anywhere in the area.

              If they can be refinished I might buy one from him (actually my wife, as she is a citizen and gun club member).

              Anyway I thought I would like to give it a try.

              I've downloaded the file you mentioned and I'm looking at it right now.