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Thread: Uniformity of Chrome Lining?

  1. #11
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    Quote Originally Posted by michael word View Post
    It sounds to me like the barrel was probably rifled off center. Probably button rifled and the button was not lined up correctly from the start and then the chrome just made it appear more to the eye due to the reflectivity. I would never accept that barrel.
    That is what it "looked" like, but don't they chrome line the barrel after it is cut?
    "First gett'n shot, then gett'n married... baaaad habits"

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  2. #12
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    Quote Originally Posted by michael word View Post
    It sounds to me like the barrel was probably rifled off center. Probably button rifled and the button was not lined up correctly from the start and then the chrome just made it appear more to the eye due to the reflectivity. I would never accept that barrel.
    the blanks are drilled with gun drills, then trued up by turning. the gun drill never bores perfectly straight, thats why they get turned after. rifling, on button and broach barrels, necessarily follows the bore line- there's no place else for the tool to go. you can't rifle "off center."

    what can any of this possibly have to do with chrome lining?

  3. #13
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    Quote Originally Posted by boltcatch View Post
    I think I know what you're getting at.

    The bore is chromed after it is cut and rifled. The plating is thin.

    On a lot of barrels, there is a bit of chrome that comes out around the crown, basically plating on the front of the muzzle. Sometimes it has a fuzzy edge, sometimes it has a sharp edge. It doesn't really affect anything, and it is not an indication that it's thicker on one side or another. I'm guessing this is what you're seeing.

    Can't really tell you what is going on with your crown without a picture, but a lot of them on the chrome lined barrels look very, er, "basic". If it shoots fine, it's probably fine.
    I have seen this before also. Question for the OP, was the barrel chopped or was it the factory cut length? I have seen some that looked uneven due to how the chrome flowed out of the muzzle. It was basically a cosmetic issue on the end of the barrel. The actual lining is a very thin layer and it would be difficult to tell how uniform it was unless the barrel was cut & crowned after the chrome was applied.

  4. #14
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    Factory in the box.
    "First gett'n shot, then gett'n married... baaaad habits"

    "If you're gonna subscribe to hero worship, at least worship a real hero."
    M4Guru

    Gal 2:20

  5. #15
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    Since chroming is a plating process, I am not sure it is even possible to get a non uniform plating thickness on relatively uniform surface like the bore of a barrel (assuming that the interior was cleaned properly).
    Last edited by 5shot; 09-06-10 at 13:33.

  6. #16
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    Quote Originally Posted by 5shot View Post
    Since chroming is a plating process, I am not sure it is even possible to get a non uniform plating thickness on relatively uniform surface like the bore of a barrel (assuming that the interior was cleaned properly).
    it's not plated, it's lined. the chrome is soaked into the steel, becomes one with it. plating would be a secondary layer, and would add thickness. since the process doesn't add any measurable thickness, it obviously cannot be "thicker" on one side or the other.

  7. #17
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    You can call it whatever, but Hard Chrome is still a plating process -

    Here is a quote from an FNH Flyer:

    • Hard chrome-plated bore for accuracy,
    corrosion resistance and long life

    Found Here: http://fnhusa1.com/PDF/FNH08FNAR.pdf Pg 3

    Also here on the M249 SAW(pg 22) http://fnhusa1.com/PDF/2010_Government_Catalog.pdf

    "Plated" and "Lined" are used interchangeably throughout their literature.
    Last edited by 5shot; 09-06-10 at 15:14.

  8. #18
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    Chrome lining is usually on the order of 0.0002" thickness.
    I'm not understanding how you could look with your naked eye and determine that the chrome is twice as thick on one side of the barrel.

    I agree with what one poster suggested above that you are probably looking at the crown or at the chamber mouth and seeing the un-even masking job that the chrome plater did.

    When they chrome the barrels, they are only chroming the inside so there's a very defined transistion where the chrome ends and the plain chromoly steel begins.
    When the barrel gets parkerized, the chrome does not take park so you can plainly see where the chrome ends.
    Don't assume that that you are seeing on the end of the crown is the THICKNESS of the chrome though.
    Last edited by AR15barrels; 09-21-10 at 20:21.
    Randall Rausch
    AR15 Barrel Guru
    California Precision Rifle Club founding member

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