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Helpin me understand BC's
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<blockquote data-quote="J E Custom" data-source="post: 363255" data-attributes="member: 2736"><p>BCs are calculated by two methods.</p><p></p><p>The G1 method is based on a comparison of the bullet your trying to measure and a standard</p><p>bullet shape that is a flat base spitzer. This is the method used by most because it has been around for a long time and the BC number is higher.</p><p></p><p>The G7 method is the most accurate comparison because it compairs your bullet to a model</p><p>shaped more like the new technology bullets we have today (Boat tailed spitzer). The reason</p><p>manufacturers don't use it is the numbers go way down,and as you know numbers sell bullets.</p><p>It is the same bullet but different numbers. The main advantage to the G7 Ballistic coefficient</p><p>is that if you test the bullet at range the drop and drift figures are a closer match (More </p><p>accurate numbers).</p><p></p><p>The measurement for BCs can start very low .100 to .200 for round ball to well over 1.000</p><p>The .510 BCs using the G1 method are as high as 1.124 but when you use the G7 method</p><p>it drops to less than .600.</p><p></p><p>All of the highest bullet BCs are on the secant ogive or the tangent ogive with boat tails because</p><p>they are longer and more aerodynamic that the other shapes of the same weight.</p><p></p><p>Round nose and flat nose bullets have a poor SD because of there shape and most are flat base</p><p>and are much shorter for there weight.</p><p></p><p>Ballistic Coefficients are not as important for some uses as it is for long range and in fact high</p><p>BC bullets are not as good as round/flat nose designe,s for thick skinned dangerous game.</p><p></p><p>To help explain what the shape of a bullet has to do with BCs (the ability to move through the</p><p>air ) I would use a simple comparison A sail boat or a tug boat . The sail boat is designed to </p><p>move through the water with the least amount of effort, But the tug boat has a different</p><p>design criteria and speed and ease through the water is not important.</p><p></p><p>I am a layman and not a ballistician so hope I have helped explain what BCs are and </p><p>the number system used. </p><p></p><p>J E CUSTOM</p></blockquote><p></p>
[QUOTE="J E Custom, post: 363255, member: 2736"] BCs are calculated by two methods. The G1 method is based on a comparison of the bullet your trying to measure and a standard bullet shape that is a flat base spitzer. This is the method used by most because it has been around for a long time and the BC number is higher. The G7 method is the most accurate comparison because it compairs your bullet to a model shaped more like the new technology bullets we have today (Boat tailed spitzer). The reason manufacturers don't use it is the numbers go way down,and as you know numbers sell bullets. It is the same bullet but different numbers. The main advantage to the G7 Ballistic coefficient is that if you test the bullet at range the drop and drift figures are a closer match (More accurate numbers). The measurement for BCs can start very low .100 to .200 for round ball to well over 1.000 The .510 BCs using the G1 method are as high as 1.124 but when you use the G7 method it drops to less than .600. All of the highest bullet BCs are on the secant ogive or the tangent ogive with boat tails because they are longer and more aerodynamic that the other shapes of the same weight. Round nose and flat nose bullets have a poor SD because of there shape and most are flat base and are much shorter for there weight. Ballistic Coefficients are not as important for some uses as it is for long range and in fact high BC bullets are not as good as round/flat nose designe,s for thick skinned dangerous game. To help explain what the shape of a bullet has to do with BCs (the ability to move through the air ) I would use a simple comparison A sail boat or a tug boat . The sail boat is designed to move through the water with the least amount of effort, But the tug boat has a different design criteria and speed and ease through the water is not important. I am a layman and not a ballistician so hope I have helped explain what BCs are and the number system used. J E CUSTOM [/QUOTE]
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