How bad is this crown?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by bookworm, Jun 7, 2009.

  1. bookworm

    bookworm Well-Known Member

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    I've been trying to figure out why I can't get my AR-15 to shoot. Basically the best 5 shot group I can muster is around 3". I posted about it here a couple months ago:

    http://www.longrangehunting.com/forums/f19/ar-15-accuracy-help-40596/

    The more I read the more I see that "everyone" with an AR-15 seems to get pretty good accuracy (< 1 moa). I have access to a boresope at work, so I decided to take a closer look at the barrel to see if anything jumped out at me. I didn't find anything inside the barrel that stood out (although I'm no professional), but below is what the crown looks like. Now again I'm no gunsmith, but this crown looks like a rat chewed on it.

    I don't know exactly what a "good" crown should look like, but can I assume that this is not it?

    Do you think that this could be my source of inaccuracy?


    [​IMG]

    [​IMG]
     
  2. AJ Peacock

    AJ Peacock Well-Known Member

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    I'd definitely get something done with that crown before I wasted any more components trying to figure it out.

    I'd also buy some rat traps :D

    AJ
     

  3. ICANHITHIMMAN

    ICANHITHIMMAN Well-Known Member

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    A thats rough looking. You could sent it out or redo it your self with a drill, brass screw and a bit of lapping compound.

    I will tell you what it cant hurt it.
     
  4. royinidaho

    royinidaho Writers Guild

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    Even if that crown didn't make any difference I couldn't live like that!

    Speaking of rats, I think a trained beaver could do better.:D

    As said above, it couldn't hurt to work it a bit.
     
  5. ss7mm

    ss7mm Writers Guild

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    I didn't know that you could crown a barrel with a cutting torch.:)
     
  6. ICANHITHIMMAN

    ICANHITHIMMAN Well-Known Member

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    ss7mm

    That last coment had me in stiches
     
  7. gamehauler

    gamehauler Well-Known Member

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    WOW! thats incredible.
     
  8. kanem

    kanem Well-Known Member

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    Bad, the crown should be sharp i never pull a brush back though a crown. Definatly get it redone. mk
     
  9. bookworm

    bookworm Well-Known Member

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    Ok - I think it is unanimous. :)

    Any idea what a re-crown should cost me?
     
  10. royinidaho

    royinidaho Writers Guild

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    25 to 45 bucks. But a compassionate smith would do it just for the good will.
     
  11. Crane

    Crane Well-Known Member

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    I would try to barely "kiss" it with a lightly abrasive ball and a dremel on slow speed; or even hand turned. I wouldn't worry too much about messing it up.
     
  12. J E Custom

    J E Custom Well-Known Member

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    All I can say is wow !!!!!!!!!

    Have your smith re crown with a 11o degree cutter and "DO NOT CHAMPHER THE BORE''
    you clean from the receiver end anyway and a sharp exit edge seems to work best for
    me.

    And as Kanem said pull the brush from breach to crown and not backwards unless you
    use a swab instead of a brush.

    J E CUSTOM
     
  13. TnTom

    TnTom Well-Known Member

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    just curious who did that work?
     
  14. nitrousmudbogger

    nitrousmudbogger Well-Known Member

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    Wow that is Sh*t! get it redone. Im w JE Custom on the 11degree. It looks like you are going to have to bring it back at least 1/4". The rifleing and everything look horrible. If that doesnt work who ever took pride in the crown prolly did that good on the rest of it and Id use it as a jack handle and get a new one.