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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Hammer ballistic coefficient tests...
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<blockquote data-quote="Pdvdh" data-source="post: 2613543" data-attributes="member: 4191"><p>I set my LabRadar to collect velocity at 20yd increments out to 100yds. As 100 is about as far as my LabRadar will collect accurate data on the 30 and 338 cal bullets.</p><p></p><p>I then compare recorded velocity amongst each group of bullets to ensure consistent velocity loss for each bullet fired. I compare velocity loss at every 20yd increment down range. It becomes obvious in short order what the average rate of velocity decay is for the bullet being tested. After I've fired, say 4 or more bullets, I develop an "averaged" MV and an "averaged" velocity for the bullet at 20 40 60 80 and 100yds. </p><p></p><p>I then input the "average" MV into my Ballistic software, along with the station pressure, temp, and RH, and adjust the bullet BC value until the Ballistic software accurately predicts my "average" downrange LabRadar velocities. </p><p></p><p>I don't know of any method of mimicking my process using a Magnetospeed Speed. Since to my knowledge, it provides only one velocity, at the muzzle.</p><p></p><p>My Labradar will commonly/normally collect bullet velocities out to 100yds for 30 and 338 cal bullet diameters. Normally 80 to 100yds for 28 cal bullets. 60-80yds for 25 cal bullets. And ~60 yds for 22 cal bullets.</p><p></p><p>If you collect accurate velocity out to 60yds, that's sufficient to calculate an accurate BC value. More distance velocities are of course, better. But the LabRadar isn't able to collect velocity past ~125yds. I used to set my LabRadar to collect velocity out to 125yds, but feel I get better / more accurate velocity data running it with the 100yd max range setting. So I set mine to report velocity at the 20 40 60 80 100yd settings.</p><p></p><p>This is somewhat similar to the method used by shooters to develop a BC value for a bullet based on measured downrange bullet drops. Reverse calculation of a bullet's BC value using a ballistics program by inputting BC values into the ballistics program, until a BC value accurately predicts the measured downrange bullet drops. Except my method eliminates the human and rifle-caused errors involved in accurate placement of bullets on target at long distance, especially under variable wind shooting conditions.</p></blockquote><p></p>
[QUOTE="Pdvdh, post: 2613543, member: 4191"] I set my LabRadar to collect velocity at 20yd increments out to 100yds. As 100 is about as far as my LabRadar will collect accurate data on the 30 and 338 cal bullets. I then compare recorded velocity amongst each group of bullets to ensure consistent velocity loss for each bullet fired. I compare velocity loss at every 20yd increment down range. It becomes obvious in short order what the average rate of velocity decay is for the bullet being tested. After I've fired, say 4 or more bullets, I develop an "averaged" MV and an "averaged" velocity for the bullet at 20 40 60 80 and 100yds. I then input the "average" MV into my Ballistic software, along with the station pressure, temp, and RH, and adjust the bullet BC value until the Ballistic software accurately predicts my "average" downrange LabRadar velocities. I don't know of any method of mimicking my process using a Magnetospeed Speed. Since to my knowledge, it provides only one velocity, at the muzzle. My Labradar will commonly/normally collect bullet velocities out to 100yds for 30 and 338 cal bullet diameters. Normally 80 to 100yds for 28 cal bullets. 60-80yds for 25 cal bullets. And ~60 yds for 22 cal bullets. If you collect accurate velocity out to 60yds, that's sufficient to calculate an accurate BC value. More distance velocities are of course, better. But the LabRadar isn't able to collect velocity past ~125yds. I used to set my LabRadar to collect velocity out to 125yds, but feel I get better / more accurate velocity data running it with the 100yd max range setting. So I set mine to report velocity at the 20 40 60 80 100yd settings. This is somewhat similar to the method used by shooters to develop a BC value for a bullet based on measured downrange bullet drops. Reverse calculation of a bullet's BC value using a ballistics program by inputting BC values into the ballistics program, until a BC value accurately predicts the measured downrange bullet drops. Except my method eliminates the human and rifle-caused errors involved in accurate placement of bullets on target at long distance, especially under variable wind shooting conditions. [/QUOTE]
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