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Does this make sense???

Discussion in 'Shooting Related Threads' started by plux001, Nov 10, 2011.

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  1. plux001

    plux001 Member

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    Am playing around with a new bore gauge...Skeets 843-200-126.

    First measured a Model 12. Full fixed. Bore .734, choke .693, difference .041.

    Top barrel Superposed. Full fixed. Bore .725, choke .685, difference .040.

    Bottom Superposed. Imp mod fixed. Bore .725, choke .702, difference .023.

    Do these numbers look right??? I thought a 12ga barrel should be .729. Also, I expected the Model 12 to fall between .033 and .035...not .041! For that matter, the same goes for the top barrel of the Superposed. Am I doing something wrong? What do ya'll think?

    Paul
     
  2. JACK

    JACK Well-Known Member Supporting Vendor

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    yes.trust the gage
     
  3. Porcupine

    Porcupine Active Member

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    My 1923 Field Model 12, bore = .728, choke = .694, constriction = .034

    My 1955 Standard Model 12, bore = .728, choke = .693, constriction = .035

    My 1960 Browning Broadway, upper barrel (fixed full), bore = .729, choke = .688, constriction = .041

    My 1960 Browning Broadway, lower barrel (fixed IM), bore = .729, choke = .700, constriction = .029

    I'd suggest trying a different gauge, for empirical purposes, then draw your own conclusions.

    LA in MA
     
  4. timb99

    timb99 Well-Known Member

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    If you measure with two different instruments, and get different answers, which one do you trust???

    I wouldn't be surprised about those numbers.

    Some of the Italian guns measure even smaller.

    Yes, nominal 12 gauge bore is .730-ish, but if you measure ten different guns from ten different manufacturers you'll get ten different measurements, anywhere from 0.723 to 0.735.

    Not completely surprised about the full chokes, either. Nominal full is 0.036 or thereabouts, but some are more. Mine is 0.042.
     
  5. mixer

    mixer Well-Known Member

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    Plux001,

    Your Browning Superposed has measurements that are exactly the same as my 1970 o/u.

    Eric
     
  6. plux001

    plux001 Member

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    Thank you all for the kind responses. I feel pretty good about my "method" for bore measurement, as I was able to duplicate it many times with exactly the same results. However, I'm not so sure about how I am measuring the choke. Obviously, the barrels are tapered to the muzzle tip. How close to the tip should I be when I'm taking my reading? The measurements I gave herein are as close to the tip as I could get and still get a good reading. Guess I am just surprised at how the nominal bore measurement varies from standard and how tight "fixed full" is. I suppose if nothing else, it confirms that no one has messed with the bores and/or chokes...

    Paul
     
  7. timb99

    timb99 Well-Known Member

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    If you're within a half inch of the muzzle, that should give you a pretty good reading. There is a short section just before the muzzle on most barrels/chokes that is not tapered.
     
  8. BigM-Perazzi

    BigM-Perazzi Well-Known Member

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    Plux, I usually set the gage to zero when in the bore. Then it's directly reading the constrictions when being removed. Saves the math...

    As stated, looks good...
     
  9. plux001

    plux001 Member

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    I have spent a great deal of time at the pattern board, but no time with a bore gauge. Looking at the results of the M12 and Superposed, you will see that the net constriction (for full) is nearly identical. Yet, there is quite a difference in nominal bore and choke. With the same load, these two barrels pattern in a very similar fashion. Would I be correct in saying that the choke measurement itself is not very meaningful without knowing the bore measurement as well? In other words, am I correct in saying it is the net constriction that really matters?

    Paul
     
  10. BigM-Perazzi

    BigM-Perazzi Well-Known Member

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  11. KENENT1

    KENENT1 Active Member

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    doesn't matter if the gauge is off, when you subtract the difference, you will get the constriction.


    tony
     
  12. halfmile

    halfmile Well-Known Member

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    The parallel section of the choke is where you measure.

    HM
     
  13. plux001

    plux001 Member

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    Maybe I'm doing something wrong. "Parallel section" was easy to find on my son's BT-99. Found no such thing on the Superposed or M12...

    Paul
     
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