Determining optimal rifle twist using the Greenhill formula.

Discussion in 'Technical Questions & Information' started by sharpie443, Oct 2, 2012.

  1. sharpie443

    sharpie443 New Member

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    I got a question from someone on youtube asking why rifling and bullets in general haven't changed much over the years. His message boiled down to him wanting to know why we don't try to make better rifling to improve accuracy. Obviously there are a number of things wrong with his question but I don't think a lot of new shooters understand rifling or how we determine what twist will gyroscopically stabilize a round.

    So I made a video explaining the Greenhill formula and how we determine what twist to use with different projectiles. I also talked about needing a faster twist with subsonic and things like that.

    I figured someone here might be interested in it. The video involves math so I’m not sure how popular it will be.

    http://www.youtube.com/watch?v=4WKztzgcnQw&list=UU_i0O7tE8cUH0CTk3VqtM6w&index=1&feature=plcp
  2. stumpjumper

    stumpjumper Member

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    interesting. i take it this applies to handguns also?
  3. 68c15

    68c15 Well-Known Member

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    there. I finally learned something today. now I'm going to bed
  4. sharpie443

    sharpie443 New Member

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    Sure. It works with any projectile. It was originally intended for use in rifled artillery. We have more precise methods for determining twist but this equation works fine for most applications. It's also the easiest to explain.
  5. B27

    B27 New Member

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    Most informative!
    Thanks! :)

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