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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Canting - the right answer
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<blockquote data-quote="Brown Dog" data-source="post: 109713" data-attributes="member: 1622"><p>JBM, Gustavo, Tiro et al,</p><p></p><p>Firstly, I need to get out more! /ubbthreads/images/graemlins/smile.gif but this is interesting, and JBM's very low (in my opinion! /ubbthreads/images/graemlins/smile.gif) horizontal displacement value is causing me dissonance!</p><p></p><p>JBM, I still can't see how you're getting such small (0.5MOA) lateral deviation. </p><p></p><p>I've sketched things out for myself to check my reasoning (and having looked at Tiro's link; I think I'm singing off the same song sheet as him! -Tiro correct me if I'm wrong!)</p><p></p><p>If the whole thing is examined in terms of angular subtension; the horizontal displacement for 10 deg cant at 1000yds must be far greater than 0.5MOA……I still think you're off by a factor of 10 or so!</p><p></p><p>[I worked this eg out for myself, metres and mils are easiest for me. Standby for a pleasing mix of metric and imperial /ubbthreads/images/graemlins/smile.gif :</p><p>My eg is 3000fps, BC 0.5, scope height 1.5in, zero range 100m. For simplicity, the boreline and the angle of departure are considered to be the same]</p><p></p><p><img src="http://i19.photobucket.com/albums/b162/thebrowndog/Slide2.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p><img src="http://i19.photobucket.com/albums/b162/thebrowndog/Slide3.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p><img src="http://i19.photobucket.com/albums/b162/thebrowndog/Slide4.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p><img src="http://i19.photobucket.com/albums/b162/thebrowndog/Slide5.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p>……well, I did say they were intended to make the issue clearer for me! </p><p></p><p>…as regards needing to factor in 'range'; to my mind this is done automatically if you think in terms of angular subtension…......in zeroing (at 0 cant) at a particular range I 'shoot out' range (drop and subtension) issues unwittingly. </p><p></p><p>In my example, the 10 deg cant effect is the same as if I had changed my scope setting by Az 3.28mils and El 0.28mils.</p><p></p><p>I can't see why it's more complicated than that, the cant simply has the same effect as a bearing and elevation change. Drop remains unchanged. The miss simply equates to the magnitude of the bearing and elevation change /ubbthreads/images/graemlins/smile.gif /ubbthreads/images/graemlins/confused.gif /ubbthreads/images/graemlins/smile.gif</p><p></p><p></p><p>Right, please now all tell me why I'm wrong! /ubbthreads/images/graemlins/smile.gif /ubbthreads/images/graemlins/smile.gif</p><p></p><p></p><p></p><p>PS...before Gustavo's original post on the 5th of this month, I have to admit that my 'interogation' of cant had never gone deeper than remembering the mnemonic "ELXEL" for work ....top prize to anyone who recognises it!</p></blockquote><p></p>
[QUOTE="Brown Dog, post: 109713, member: 1622"] JBM, Gustavo, Tiro et al, Firstly, I need to get out more! [img]/ubbthreads/images/graemlins/smile.gif[/img] but this is interesting, and JBM's very low (in my opinion! [img]/ubbthreads/images/graemlins/smile.gif[/img]) horizontal displacement value is causing me dissonance! JBM, I still can’t see how you’re getting such small (0.5MOA) lateral deviation. I’ve sketched things out for myself to check my reasoning (and having looked at Tiro’s link; I think I’m singing off the same song sheet as him! -Tiro correct me if I'm wrong!) If the whole thing is examined in terms of angular subtension; the horizontal displacement for 10 deg cant at 1000yds must be far greater than 0.5MOA……I still think you’re off by a factor of 10 or so! [I worked this eg out for myself, metres and mils are easiest for me. Standby for a pleasing mix of metric and imperial [img]/ubbthreads/images/graemlins/smile.gif[/img] : My eg is 3000fps, BC 0.5, scope height 1.5in, zero range 100m. For simplicity, the boreline and the angle of departure are considered to be the same] [img]http://i19.photobucket.com/albums/b162/thebrowndog/Slide2.jpg[/img] [img]http://i19.photobucket.com/albums/b162/thebrowndog/Slide3.jpg[/img] [img]http://i19.photobucket.com/albums/b162/thebrowndog/Slide4.jpg[/img] [img]http://i19.photobucket.com/albums/b162/thebrowndog/Slide5.jpg[/img] ……well, I did say they were intended to make the issue clearer for me! …as regards needing to factor in ‘range’; to my mind this is done automatically if you think in terms of angular subtension…......in zeroing (at 0 cant) at a particular range I ‘shoot out’ range (drop and subtension) issues unwittingly. In my example, the 10 deg cant effect is the same as if I had changed my scope setting by Az 3.28mils and El 0.28mils. I can't see why it's more complicated than that, the cant simply has the same effect as a bearing and elevation change. Drop remains unchanged. The miss simply equates to the magnitude of the bearing and elevation change [img]/ubbthreads/images/graemlins/smile.gif[/img] [img]/ubbthreads/images/graemlins/confused.gif[/img] [img]/ubbthreads/images/graemlins/smile.gif[/img] Right, please now all tell me why I'm wrong! [img]/ubbthreads/images/graemlins/smile.gif[/img] [img]/ubbthreads/images/graemlins/smile.gif[/img] PS...before Gustavo's original post on the 5th of this month, I have to admit that my 'interogation' of cant had never gone deeper than remembering the mnemonic "ELXEL" for work ....top prize to anyone who recognises it! [/QUOTE]
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