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new twist on b.c.'s
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<blockquote data-quote="goodgrouper" data-source="post: 11983" data-attributes="member: 2852"><p><strong>Re: new twist on b.c.\'s</strong></p><p></p><p>Dave King</p><p> Yes Dave, all I did was chrono the bullets at the muzzle and then at 500 yards and then I called Dave Brown at Sierra to get the formula for calculating bc. He told me that the formula encorporates equational calculus and it was much easier to let the software he uses to calculate everything. So I told him the humidity, temp, elevation, barometric pressure, and wind conditions and he told me the bc over the phone. Another thing he told me which I did not know is that the distance between both chronos has to be measured exactly from center to center not just from the last skyscreen on the first chrono to the first skyscreen on the last chrono!</p><p> Just a side note: I actually chronoed several bullets that day out of some of my other wildcats. I did a 75 gr. a-max out of a 22-250 improved, a 55 gr. blitzking out of a different 22-250 improved with a slow twist, a 40 gr. v-max from a .223-4000, and a 180 scirroco from a .300 win mag. The results were .479 for the amax, .299 for the blitzking, .239 for the vmax, and .538 for the scirocco. All bc's were higher than the manufacturer's calculations!</p><p></p><p>[ 09-15-2004: Message edited by: goodgrouper ]</p></blockquote><p></p>
[QUOTE="goodgrouper, post: 11983, member: 2852"] [b]Re: new twist on b.c.\'s[/b] Dave King Yes Dave, all I did was chrono the bullets at the muzzle and then at 500 yards and then I called Dave Brown at Sierra to get the formula for calculating bc. He told me that the formula encorporates equational calculus and it was much easier to let the software he uses to calculate everything. So I told him the humidity, temp, elevation, barometric pressure, and wind conditions and he told me the bc over the phone. Another thing he told me which I did not know is that the distance between both chronos has to be measured exactly from center to center not just from the last skyscreen on the first chrono to the first skyscreen on the last chrono! Just a side note: I actually chronoed several bullets that day out of some of my other wildcats. I did a 75 gr. a-max out of a 22-250 improved, a 55 gr. blitzking out of a different 22-250 improved with a slow twist, a 40 gr. v-max from a .223-4000, and a 180 scirroco from a .300 win mag. The results were .479 for the amax, .299 for the blitzking, .239 for the vmax, and .538 for the scirocco. All bc's were higher than the manufacturer's calculations! [ 09-15-2004: Message edited by: goodgrouper ] [/QUOTE]
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