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375-408 CheyTac (Kirby Alert!!!!!!) question
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<blockquote data-quote="Mountainsheep" data-source="post: 120673" data-attributes="member: 5875"><p>Kirby,</p><p>I am very pleased that in some areas my formula correlated with your actual application results. I am extremely impressed that you caught the deceleration ratio discrepancy at the 2000-yard range, do not kid yourself, this stuff is by no means above you. That was no typo, that is just evidence of application vs. theory. According to Sierra, the B.C. of the 300-grain SMK abruptly changes at 1800 fps; this figure is not in correlation to the constant decline in the FC (frequency of collision) variable. The faster bullet did not speed up; it just did not cross the deceleration factor until sometime after the slower bullet's program had made a parameter adjustment causing a spike in its ratio of deceleration. (sorta like hitting a bug in cyberspace /ubbthreads/images/graemlins/grin.gif). I did use altitude as a factor, but the air temp, humidity, pressure and barometer figures are an average of atmospheric conditions at 3500' obtained from a GOOGLE search. (I'm too lazy to call the Billings airport.) The cyber model atmosphere was constructed from perfect little cubic particles that were forced away from the meplat at a 168° or a 192° angle and simply ceased to exist after rising or falling .169" from the bullets centerline. In other words there was very little resistance past the oglive and no posterior turbulence effect. I did not allow for any pitch or yaw from the projectile and also no gravitational pull. I omitted these factors just to compare the deceleration and energy depletion ratio and because I'm lazy. This example should prove three things: 1.) Your observations through experience are likely correct. 2.) If the bullets become unstable the increased drag could affect the faster bullet enough to bring it to sub-sonic velocity sooner than the lighter load. 3.) Doing math calculations like this on a weekend indicate I do not have a life /ubbthreads/images/graemlins/grin.gif. I think a 6.5 Allen Xpress would solve that problem!</p><p>This thread is very entertaining, if not somewhat off the original subject, I hope it continues.</p><p>Dave</p></blockquote><p></p>
[QUOTE="Mountainsheep, post: 120673, member: 5875"] Kirby, I am very pleased that in some areas my formula correlated with your actual application results. I am extremely impressed that you caught the deceleration ratio discrepancy at the 2000-yard range, do not kid yourself, this stuff is by no means above you. That was no typo, that is just evidence of application vs. theory. According to Sierra, the B.C. of the 300-grain SMK abruptly changes at 1800 fps; this figure is not in correlation to the constant decline in the FC (frequency of collision) variable. The faster bullet did not speed up; it just did not cross the deceleration factor until sometime after the slower bullet’s program had made a parameter adjustment causing a spike in its ratio of deceleration. (sorta like hitting a bug in cyberspace [img]/ubbthreads/images/graemlins/grin.gif[/img]). I did use altitude as a factor, but the air temp, humidity, pressure and barometer figures are an average of atmospheric conditions at 3500’ obtained from a GOOGLE search. (I’m too lazy to call the Billings airport.) The cyber model atmosphere was constructed from perfect little cubic particles that were forced away from the meplat at a 168° or a 192° angle and simply ceased to exist after rising or falling .169” from the bullets centerline. In other words there was very little resistance past the oglive and no posterior turbulence effect. I did not allow for any pitch or yaw from the projectile and also no gravitational pull. I omitted these factors just to compare the deceleration and energy depletion ratio and because I’m lazy. This example should prove three things: 1.) Your observations through experience are likely correct. 2.) If the bullets become unstable the increased drag could affect the faster bullet enough to bring it to sub-sonic velocity sooner than the lighter load. 3.) Doing math calculations like this on a weekend indicate I do not have a life [img]/ubbthreads/images/graemlins/grin.gif[/img]. I think a 6.5 Allen Xpress would solve that problem! This thread is very entertaining, if not somewhat off the original subject, I hope it continues. Dave [/QUOTE]
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