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I read section 1-4pm Lyman reloading hand book and got into the work ups and was wondering in the top right corner of each load there is BC and SD with #s next to them. I looked back to find out what they mean and the only things I can come up with is BC= Ballistic Coefficient and SD= Seating Depth. Is this correct? I'll keep looking but would appreciate the help. Thank u!
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Google Ballistic Coefficient. Will most likely get more information than you wanted.
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I understood ballistic coefficient pretty well from reading the book. But don't recall seeing it as BC. But looking at it on google I see it abreviated. Thank u for the response. Now looking at SD?Comment
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SD = Standard Deviation means the average range of velocity variance of a specific load. Low SD usually correlates to less vertical stringing when group shooting and is a measure of how accurate a load can be.
BC = Ballistic Coefficient is a measure of how a projectile flies in air and is effected by wind. BC determines the rate air resistance slows a projectile and/or crosswind deflects it. How fast a projectile slows from wind resistance determines the parabola of it's trajectory.Comment
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SD is Sectional Density.Comment
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Sectional density is the ratio of an object's mass to its cross-sectional area. It conveys how well an object's mass is distributed (by its shape) to overcome resistance.Comment
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Thank you everyone for all the help.Comment
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Here's a great resource:
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Heh, I asked the same question a few months ago.
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Take a look at Brian Litz book, Applied Ballistics for Long Range Shooting.
You will learn more about both BC (including his pioneering work, measuring G7 BC's) and SD (Sectional Density).
It's an invaluable resource and addition to your firearms library.Comment
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Thanks. And I read the other thread from the link above. That helped along with all the responses. About the book written above, is it all about math?Comment
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