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20ga vs. 12ga QUESTION

Discussion in 'Uncategorized Threads' started by Loyac, Mar 10, 2007.

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  1. Loyac

    Loyac Member

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    Shooting the same 1 oz #8 1200 fps factory load out of two 28" barrel guns, one a 20ga and the other a 12... What constriction would I have to use in the 20ga 391 to get the same diameter of pattern at 40 yards as the 12ga 391 choked IM? Thanks! John
     
  2. Brian in Oregon

    Brian in Oregon Well-Known Member

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    Get a choke marked IM. And barrel length makes no difference.<br>
    <br>
    The caveat is that not all individual barrels behave the same, but this would be a general rule and the best place to start.<br>
    <br>
    The 20ga strings shot more, but if the chokes are made right, they take this into account by being made for pattern.<br>
    <br>
    If you want actual amount of constriction, you'll have to consult what constriction is being used for 20ga IM.
     
  3. zzt

    zzt Well-Known Member

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  4. hmb

    hmb Well-Known Member

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    The answer to the question is .025 constriction. Give or take a few thousanths either way. You never know for sure. HMB
     
  5. GordonWood421

    GordonWood421 TS Member

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    In the "old" days , the amount of choke ; IM , Mod , IC etc ; were defined by the % of shot that would be in a particular circle at a particular distance . Truth be known , the amount of constriction that provided a particular performance may have been different from gauge to gauge . Another train of thought was that it was more related to "area" than to "diameter" at the muzzle .

    Regardless , the only real way to determine how a particular choke tube/barrel or fixed barrel performs is to put it on paper . It is amazing as to how some combination is reported by the shooter who has never been near a patterning plate/frame , much less counted the hundreds of holes involved .

    Charlie
     
  6. Loyac

    Loyac Member

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    I thank you all. John
     
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