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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Any Tips for a New Loadbase User?
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<blockquote data-quote="Pdvdh" data-source="post: 393546" data-attributes="member: 4191"><p>Tweak the DC, or Drag Coefficient. The default value is 0.500. You can play with it now and see how it changes your predicted drops. Increase it to 0.600 and see what it does to the 1000 versus 1400 moa. Then drop it to 0.400 and see what happens. You'll see the down range velocities changing as you tweak the DC. In LB3, the DC is the primary parameter used in modeling the rate of loss of bullet velocity - what Gus calls the Drag Curve - as I understand it.</p><p></p><p>I've tested three bullets for 985 yd velocities now with LB3 and Litz's G7 BCs, and the 985 yd velocities were all amazingly close to LB3 predicted velocity. Certainly well within the accuracy rating of my chronographs. These results were with the LB3 default DC value of 0.500. </p><p></p><p>The three I tested were the 7mm 168gr Berger VLD, the .308 210gr Berger VLD, and the 7mm 162gr Hornady A-Max. </p><p></p><p>Anyhow - after you chronograph your MV and come to believe you've got a pretty accurate MV input value, if you then still have slight disagreement at the 1000 and 1400 yd ranges, I'd tweak the DC.</p></blockquote><p></p>
[QUOTE="Pdvdh, post: 393546, member: 4191"] Tweak the DC, or Drag Coefficient. The default value is 0.500. You can play with it now and see how it changes your predicted drops. Increase it to 0.600 and see what it does to the 1000 versus 1400 moa. Then drop it to 0.400 and see what happens. You'll see the down range velocities changing as you tweak the DC. In LB3, the DC is the primary parameter used in modeling the rate of loss of bullet velocity - what Gus calls the Drag Curve - as I understand it. I've tested three bullets for 985 yd velocities now with LB3 and Litz's G7 BCs, and the 985 yd velocities were all amazingly close to LB3 predicted velocity. Certainly well within the accuracy rating of my chronographs. These results were with the LB3 default DC value of 0.500. The three I tested were the 7mm 168gr Berger VLD, the .308 210gr Berger VLD, and the 7mm 162gr Hornady A-Max. Anyhow - after you chronograph your MV and come to believe you've got a pretty accurate MV input value, if you then still have slight disagreement at the 1000 and 1400 yd ranges, I'd tweak the DC. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
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Any Tips for a New Loadbase User?
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