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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Help with BC calculation
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<blockquote data-quote="milanuk" data-source="post: 35204" data-attributes="member: 376"><p>Jerry, </p><p></p><p>It would be helpful if you could tell us what your scope height above the bore is... using JBM on the web, it appears to make a significant difference. Me thinks your chrono may be b0rked? That's the only way I could come close to your numbers:</p><p></p><p>Trajectory (Basic) Output</p><p></p><p>--------------------------------------------------------------------------------</p><p></p><p>Input Data</p><p>Muzzle Velocity: 3250.0 ft/sec </p><p>Ballistic Coefficient: 0.520 </p><p>Drag Function: G1 </p><p>Bullet Weight: 140 grains </p><p>Sight Height: 2.50 inches </p><p>Wind Cross Speed: 10 mph </p><p>LOS Angle: 0 degrees </p><p>Target Speed: 10 mph </p><p>Zero Range: 100 yards </p><p>Temperature: 85.0 °F </p><p>Barometric Pressure: 29.50 in Hg </p><p>Relative Humidity: 30.0 % </p><p>Altitude: 0 feet </p><p>Air Density: 93 % of Sea Level </p><p></p><p></p><p>--------------------------------------------------------------------------------</p><p></p><p>Calculated Table</p><p>Elevation: 4.039 moa </p><p>Azimuth: 0.000 moa </p><p></p><p>Range Velocity Energy Momentum Drop Windage Lead Time </p><p>(yards) (ft/sec) (ft-lbs) (lbs-sec) (moa) (moa) (moa) (sec) </p><p>100 3063.7 2917.8 1.90 -0.0 0.5 16.0 0.095 </p><p>200 2884.8 2587.0 1.79 -0.6 1.0 16.5 0.196 </p><p>300 2712.9 2287.8 1.69 -2.1 1.5 17.0 0.303 </p><p>400 2547.6 2017.5 1.58 -4.0 2.0 17.5 0.417 </p><p>500 2388.8 1773.9 1.49 -6.2 2.6 18.1 0.539 </p><p>600 2236.0 1554.1 1.39 -8.6 3.2 18.7 0.669 </p><p>700 2088.1 1355.3 1.30 -11.2 3.9 19.4 0.808 </p><p>800 1946.1 1177.3 1.21 -14.2 4.6 20.1 0.957</p></blockquote><p></p>
[QUOTE="milanuk, post: 35204, member: 376"] Jerry, It would be helpful if you could tell us what your scope height above the bore is... using JBM on the web, it appears to make a significant difference. Me thinks your chrono may be b0rked? That's the only way I could come close to your numbers: Trajectory (Basic) Output -------------------------------------------------------------------------------- Input Data Muzzle Velocity: 3250.0 ft/sec Ballistic Coefficient: 0.520 Drag Function: G1 Bullet Weight: 140 grains Sight Height: 2.50 inches Wind Cross Speed: 10 mph LOS Angle: 0 degrees Target Speed: 10 mph Zero Range: 100 yards Temperature: 85.0 °F Barometric Pressure: 29.50 in Hg Relative Humidity: 30.0 % Altitude: 0 feet Air Density: 93 % of Sea Level -------------------------------------------------------------------------------- Calculated Table Elevation: 4.039 moa Azimuth: 0.000 moa Range Velocity Energy Momentum Drop Windage Lead Time (yards) (ft/sec) (ft-lbs) (lbs-sec) (moa) (moa) (moa) (sec) 100 3063.7 2917.8 1.90 -0.0 0.5 16.0 0.095 200 2884.8 2587.0 1.79 -0.6 1.0 16.5 0.196 300 2712.9 2287.8 1.69 -2.1 1.5 17.0 0.303 400 2547.6 2017.5 1.58 -4.0 2.0 17.5 0.417 500 2388.8 1773.9 1.49 -6.2 2.6 18.1 0.539 600 2236.0 1554.1 1.39 -8.6 3.2 18.7 0.669 700 2088.1 1355.3 1.30 -11.2 3.9 19.4 0.808 800 1946.1 1177.3 1.21 -14.2 4.6 20.1 0.957 [/QUOTE]
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Help with BC calculation
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