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Thread: 75 grain amax 222 rem

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  1. 13-09-2016, 07:22 AM #1
    Marty Henry
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    Use this formula to see if its feasable. If the bullet speed is over 2800 fps 180x bullet diameter squared/ bullet length = twist, if speed is below 2800 replace 180 with 150.
    This (the greenhill formula) and works for any copper and lead core bullet. Sometimes a bullet starts out stable but as speed drops precession sets in and no hits on target.
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  2. 13-09-2016, 07:34 AM #2
    kiwijames
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    Quote Originally Posted by Marty Henry View Post
    Use this formula to see if its feasable. If the bullet speed is over 2800 fps 180x bullet diameter squared/ bullet length = twist, if speed is below 2800 replace 180 with 150.
    This (the greenhill formula) and works for any copper and lead core bullet. Sometimes a bullet starts out stable but as speed drops precession sets in and no hits on target.
    Ha ha. I think you will have @Ginga lost with the first function.
    The range of what we think and do is limited by what we fail to notice. And because we fail to notice that we fail to notice, there is little we can do to change; until we notice how failing to notice shapes our thoughts and deeds
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