Pennsylvania Firearm Owners Association
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  1. #1
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    Default Brownells says galvanic corrosion isn't a real problem

    I'm not contesting what they are saying. Just sharing.





    -Zach

  2. #2
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    Default Re: Brownells says galvanic corrosion isn't a real problem

    Haha! This came up in my last build thread when I was at the point of installing my barrel.
    The whole internet says that you have to use AeroShell "somenumber" grease ONLY in order to prevent this corrosion from locking your barrel to your upper.
    I said "fuck it", I'm not paying $12 of a dab of this wonder grease - I used the synthetic axle grease that sits in a tub in my garage.
    I called to check my ZIP CODE!....DY-NO-MITE!!!

  3. #3
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    Default Re: Brownells says galvanic corrosion isn't a real problem

    Both vids are correct; galvanic corrosion of an AR barrel, barrel nut, and upper receiver is a non-problem due in part to non-electrically-conductive anodizing on the receiver. In addition, there is usually no corrosion-promoting electrolyte present. Corrosion won't happen without an electrolyte; it doesn't have to be sea water with ~ 3.5% salt, plain tap water is impure enough to carry a charge between aluminum and steel. ARs are simply too dry to corrode, the vast majority of the time. The people who use their ARs/M4s/M16s in water generally clean them well afterward, so even those guns aren't going to see "white rust" form like it does under the silver colored powder coating on older Toyota aluminum wheels.

    Noah
    Wisdom and knowledge shall be the stability of thy times.

  4. #4
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    Default Re: Brownells says galvanic corrosion isn't a real problem

    They are correct, even if they don't know why! If one recalls the 'galvanic series' chart from chemistry, the two metals are fairly close in potential, so the chances of galvanic corrosion are minimal.

    [ATTACH=CONFIG]132200[/img]
    Attached Images Attached Images
    Resistance to tyrants is obedience to God.

  5. #5
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    Default Re: Brownells says galvanic corrosion isn't a real problem

    My understanding of it isn't that the metals themselves are the issue. It is an issue when you use graphite based lubricants (which lots of lubricants are).

    Again, I'm not arguing the videos. Just passing the argument along.

    -Zach

  6. #6
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    Default Re: Brownells says galvanic corrosion isn't a real problem

    The same thing happened to those "forever" doors sold by home dumpster when they first opened up.

  7. #7
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    Default Re: Brownells says galvanic corrosion isn't a real problem

    For awhile I thought I'd be tightening the barrel nut over and over until it completely seated because of the different expansion rates of the two metals.
    If you've ever wrenched on a Harley Shovelhead, or anything with aluminum heads, you know what I'm talking about.
    However I don't think the temp cycle is extreme enough, no matter how hard you run it, to warrant being concerned since I've never had to retighten one.

    I believe the only time you need to worry about corrosion reaction is when that unfortunate boating accident occurs.

  8. #8
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    Default Re: Brownells says galvanic corrosion isn't a real problem

    Quote Originally Posted by P89 View Post
    For awhile I thought I'd be tightening the barrel nut over and over until it completely seated because of the different expansion rates of the two metals.
    If you've ever wrenched on a Harley Shovelhead, or anything with aluminum heads, you know what I'm talking about.
    However I don't think the temp cycle is extreme enough, no matter how hard you run it, to warrant being concerned since I've never had to retighten one.

    I believe the only time you need to worry about corrosion reaction is when that unfortunate boating accident occurs.
    It's not the head, it's the gasket for the reason or need to retorque the head after heat cycles.

    AR's have no gasket, metal on metal so no need to retoque and no torque lost.

  9. #9
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    Default Re: Brownells says galvanic corrosion isn't a real problem

    I disagree. The gasket material can be any of several different compounds depending on usage.
    Aluminum alloys have a linear thermal expansion (10-6 in/(in oF)) of anywhere between roughly 9 & 13 depending on the alloy.
    Iron & steel, depending on the alloy, has an expansion rate of around 6.
    It will take several heat cycles between 70 & 500 degrees to get these two to play well together.

    I'm referring to extremes that an AR may not ever experience.

  10. #10
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    Default Re: Brownells says galvanic corrosion isn't a real problem

    Quote Originally Posted by Jhaydeno View Post
    They are correct, even if they don't know why! If one recalls the 'galvanic series' chart from chemistry, the two metals are fairly close in potential, so the chances of galvanic corrosion are minimal.

    [ATTACH=CONFIG]132200[/img]
    Maybe somebody should send this chart to the You're a peein' car makers.

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