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A little choke information?

Discussion in 'Shooting Related Threads' started by GrandpasArms, Dec 7, 2012.

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  1. GrandpasArms

    GrandpasArms TS Supporters TS Supporters

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    Last weekend I smoked 24 and missed number 25 on a squad. An experienced shooter on the line with me said he saw the shot pattern as it whizzed passed the target. He said it was about "this size" - and held his hands our shaping an invisible ball a little larger than a basketball - under 10 inches. That seemed too small. I shoot a 34 inch BT99 with what I've believed to be a fixed full choke. The barrel is not marked.

    Maybe Jim was being kind when he demonstrated a 10-inch "ball". I took a digital micrometer to the barrel today and it measures 0.685. I rotated the jaws and the number changed a little, from the .685 to 0.688. According to the link above, that's an EXTRA FULL.

    I'm probably over analyzing this - as I often do. Any input?

    Larry
     
  2. Scott Johnson

    Scott Johnson Well-Known Member

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    Center the bird and it does not matter how big or small the pattern is. My point is concentrate on centering, not choke, choke is not the issue, we all face it. Scott
     
  3. Oregunner

    Oregunner Well-Known Member

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    Browning has a system of marking the choke constriction on fixed choke guns. There should be an asterick on the side of the barrel block for Full. Mark
     
  4. GrandpasArms

    GrandpasArms TS Supporters TS Supporters

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    Correct, Oregunner. There's one * on the machined part. I was looking on the blued barrel as I would on a Rem 1100. Thanks.
     
  5. bluskyshooter

    bluskyshooter Active Member

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    I've only been at this for 2 years - so take this as you may. I had an older 34" BT-99 with fixed full choke. When I broke a 16yd target ... it was really crushed. But after a while shooting it for 16 yds ... something felt wrong to me. I just couldnt avoid a few misses here and there. Eventually, I stopped using the BT-99 in favor of a Browning with Invector Plus barrels and an IM choke. Broken birds werent "crushed" quite so hard ... but my average went up 2-3 birds. My conclusion - a full-choked BT-99 may be a great 27yd gun (I dont know) .... but for me it seemed too tightly choked for 16 yds. Now, if you are a "big dog" shooter who can center shots perfectly 99% of the time ... then have at it.
     
  6. hmb

    hmb Well-Known Member

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    If you want to know what the choke is you need two measurements. You need the barrel diameter and the choke diameter. Subtract the choke diameter from the barrel diameter and you will have the amount of constriction. That constriction will tell you what the choke is. HMB
     
  7. drgondog

    drgondog Member

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    IIRC the old BT99 had a .728-.729 bore. Your choke (if the recollection is correct) would be .039-.040 which is a 10/10 choke.

    My experience has been that chokes from .032-.040 have progressively hot Hot Center concentrations and tend to pattern less effectively in the 30-20" diameter ring while 'blotting out' the inner 20".

    The Euro guns were typically around .724-.726 or 18.4 mm for the older M32, Perazzi, Beretta, etc
     
  8. miketmx

    miketmx Well-Known Member

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    I think a too open choke will have a weaker core without contributing any more useful pellets to the 20" - 30" fringe. I believe in the research by Dr. A C Jones and Roger Giblin that the most efficient choke will produce a 75% - 80% pattern in a 30" circle at the distance you break the target. I use 32 yards for Singles and 42 yards for Handicap.
     
  9. ivanhoe

    ivanhoe Well-Known Member

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    "I had an older 34" BT-99 with fixed full choke. When I broke a 16yd target ... it was really crushed. But after a while shooting it for 16 yds ... something felt wrong to me. I just couldnt avoid a few misses here and there. Eventually, I stopped using the BT-99 in favor of a Browning with Invector Plus barrels and an IM choke."

    blusky you need to remember it you changed guns you may also have changed POI which could also account for the increase in your average.

    Bob Lawless
     
  10. timb99

    timb99 Well-Known Member

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    To the original poster;

    If you "smoked" 24 out of 25 on that round, it seems the pattern was just fine for the 24 you broke. And the miss on 25 was a case of mis-pointing by the nut pulling the trigger (you.)

    You're over-thinking this.

    Realistically speaking, going to a more open choke will probably NOT get you a target you would have missed with the tight choke.
     
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