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How To Determine Choke Tube Size

Discussion in 'Shooting Related Threads' started by supersenior, Oct 2, 2012.

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  1. supersenior

    supersenior Member

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    I have a Briley XFULL choke tube for my BT 99 Plus.
    Briley states that it's 040.
    Without using a bore gauge (don't have one) is there a way to measure this choke and arrive at .040?
    Can Dial Calipers be used to determine the above?

    Borden ZEE
     
  2. wayneo

    wayneo Active Member

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    Yes dial calipers can be used. Assuming your tubes are Invector Plus, the bore of your gun will be around 0.745". So, minus 0.40" an extra full should put that choke at 0.705". Full 0.710", IM 0.715" etc. My Carlson's Full is 0.710". Those numbers are ballpark figures, Briley might have 0.700" as an extra full.

    Wayne
     
  3. BigM-Perazzi

    BigM-Perazzi Well-Known Member

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    Unfortunately, without being able to reach down and measure the bore dia, you're guessing.
     
  4. Oregunner

    Oregunner Well-Known Member

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    Ask around at your club if anyone has a barrel bore gauge, or buy one from The Unloader, who sells them on this site. Good investment. Mark
     
  5. wayneo

    wayneo Active Member

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    He is asking what the choke should measure, not the bore. An extra full should be between 0.700 and 0.705" with Invector+ tubes.

    Wayne
     
  6. hmb

    hmb Well-Known Member

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    Wanye, You only have half of the equation. It should measure .040 less than the bore diameter. You have to have both measurements to know the amount of constriction. HMB
     
  7. Oregunner

    Oregunner Well-Known Member

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    The barrel bore gauge will tell you the barrel and choke diameter, then as Bill Clinton says, it's just a little arithmetic. Mark
     
  8. jayco32

    jayco32 TS Member

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    The bore size on a lot of guns is not as advertised. My Browning is shown to be a .742 bore. When I measured it with a bore gauge the single barrel is .738 and the O/U is .736. So, as you can see you need to know both the bore diameter and the choke to calculate the actual constriction. Hope this helps.
     
  9. wayneo

    wayneo Active Member

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    Thats true HMB, but no choke maker measures your bore. They know an Invector+ bore is 0.745" + or - a couple of thousands. You can order chokes and buy them off the shelf, and they screw right in. Knowing the bore of fixed choked barrels was the only way to tell what constriction you had. Carlson's extra full measures 0.700" and full is 0.710". Thats close enough for me.

    Wayne
     
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