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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Independently verified BCs for Whiskey 3 Precision Bullets
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<blockquote data-quote="Michael Courtney" data-source="post: 983183" data-attributes="member: 28191"><p>Thanks for the update. </p><p></p><p></p><p></p><p>Right. I think a lot of companies depend on the fact that very few shooters will actually measure the BCs, but rather just be happy with good accuracy and high advertised BCs. We blissfully shot Noslers for years at ranges to 250 yards, and never noticed the BC problem until we started shooting longer range, which pushed us into measuring BCs with the near and far chronograph method. After we published our first BC paper in 2007, people began asking us to measure BCs of different bullets and to address more challenging drag problems (effects of Sg, air density, damping of pitch and yaw, etc.)</p><p></p><p></p><p></p><p>We've found that velocity measurements with infrared skyscreens are rock solid dependable. When we measure BCs, we start with two or three chronographs all in a row 10, 12, and 14 feet from the muzzle to confirm that all three are reading the same. Then we move the middle and far chronographs out to their positions, usually 160 and 310 feet or 310 and 610 feet. Sometimes we don't use the middle chronograph. The middle chronograph tells us more about stability and damping of pitch and yaw than it does about BC, so its use depends on the purpose of the experiment. Lining up three chronographs is more work and increases the risk of shooting one.</p><p></p><p></p><p></p><p>This approach has been known for years to generate BCs that are overly optimistic by 20-30% compared with what real shooters will see. From 2004-2008 several of the bullet companies (Berger, Barnes, Hornady) moved to more reliable techniques based on actually measuring BCs. Sierra and Speer have long used real and reliable methods of BC determination.</p></blockquote><p></p>
[QUOTE="Michael Courtney, post: 983183, member: 28191"] Thanks for the update. Right. I think a lot of companies depend on the fact that very few shooters will actually measure the BCs, but rather just be happy with good accuracy and high advertised BCs. We blissfully shot Noslers for years at ranges to 250 yards, and never noticed the BC problem until we started shooting longer range, which pushed us into measuring BCs with the near and far chronograph method. After we published our first BC paper in 2007, people began asking us to measure BCs of different bullets and to address more challenging drag problems (effects of Sg, air density, damping of pitch and yaw, etc.) We've found that velocity measurements with infrared skyscreens are rock solid dependable. When we measure BCs, we start with two or three chronographs all in a row 10, 12, and 14 feet from the muzzle to confirm that all three are reading the same. Then we move the middle and far chronographs out to their positions, usually 160 and 310 feet or 310 and 610 feet. Sometimes we don't use the middle chronograph. The middle chronograph tells us more about stability and damping of pitch and yaw than it does about BC, so its use depends on the purpose of the experiment. Lining up three chronographs is more work and increases the risk of shooting one. This approach has been known for years to generate BCs that are overly optimistic by 20-30% compared with what real shooters will see. From 2004-2008 several of the bullet companies (Berger, Barnes, Hornady) moved to more reliable techniques based on actually measuring BCs. Sierra and Speer have long used real and reliable methods of BC determination. [/QUOTE]
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Independently verified BCs for Whiskey 3 Precision Bullets
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