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Thread: 13 twist barrels

  1. #16
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    Quote Originally Posted by vargetman View Post
    Al it is under Resources on the top of Bergers web page. Put your pointer on resources and you will see ballistics on the left.

    John
    tx

    I'll try it

  2. #17
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    Quote Originally Posted by vargetman View Post
    Al it is under Resources on the top of Bergers web page. Put your pointer on resources and you will see ballistics on the left.

    John
    All's I find is the same stability calculator I used the first time

  3. #18
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    Smile Some accurate twist rate calculators!

    http://www.jbmballistics.com/cgi-bin/jbmdrag-5.1.cgi

    http://www.geoffrey-kolbe.com/barrel_twist.htm

    Also, Lilja barrels still offers a free down-load of a program very similar to that of [the late] William (Bill) C. Davis Jr's
    Tioga Engineering program. https://riflebarrels.com/bullet-design/

    Any/all of these provide twist rate DATA which you can, "take to the bank". How do I know? I've invested the $ and the time, and proved them (in BR competition), and also via bullet length/weight/twist testing, all the way to less than Sg 1.0. There is no precision penalty at Sg1.5.

    One can waltz along the edge, purchasing piles of barrels, looking for that "hummer", or, purchase a barrel/twist which completely damps the yaw & pitch . . . advantage to those who, "dare to be different", and go with Sg 1.5.

    When adhering to the model where a gyroscopic stability factor (Sg) of 1.0 produces a stable (not tumbling) bullet, and Sg 1.5 is desired (nice safety net), with a minimum of Sg 1.4, to damp yaw & pitch, the contemporary MILLER FORMULA calculations rarely correlate with the well proven calculators (above) - I avoid Miller formula calculators, "like the plague". RG
    Last edited by R.G. Robinett; 01-04-2020 at 12:46 PM.

  4. #19
    Join Date
    Jan 2013
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    Quote Originally Posted by alinwa View Post
    Can you provide a link please? I looked all over the site, even plugged some guesses into the stability calcuprogramulator but didn't find that to which you refer sir
    In berger site the only calculator is extraction of Miller equation that is not right because don't take care about the shape of any bullets. What i mean is that Berger suggest of bullets made in .825 a twist rate of barrel 13 or faster and only for jackets .790 like the column they can be shoot in 14 twist rate or faster. This is not simply a coincidence ... If you take this information into consideration you will have a simple answers. For better calculation of stability take care of Randy Robinet answer in quote of this topic.

  5. #20
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    You would think with Berger having Bryan Litz as a contractor of some sort, they would have him bring there programs into this century

  6. #21
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    Quote Originally Posted by ity60107 View Post
    In berger site the only calculator is extraction of Miller equation that is not right because don't take care about the shape of any bullets. What i mean is that Berger suggest of bullets made in .825 a twist rate of barrel 13 or faster and only for jackets .790 like the column they can be shoot in 14 twist rate or faster. This is not simply a coincidence ... If you take this information into consideration you will have a simple answers. For better calculation of stability take care of Randy Robinet answer in quote of this topic.
    The Berger Stability Calculator is for Boat Tail Bullets ONLY.
    So Berger Column Flat Base are not relevant or any Flat Base for the Berger Calculator.

  7. #22
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    Quote Originally Posted by gfpd View Post
    you would think with berger having bryan litz as a contractor of some sort, they would have him bring there programs into this century
    lol!!

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