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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Canting - the right answer
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<blockquote data-quote="JBM" data-source="post: 109656" data-attributes="member: 1969"><p>[ QUOTE ]</p><p>The basic formulas we are using are:</p><p></p><p>horizontal projection: X = drop*sin ß</p><p> </p><p>vertical projection: Y = drop*(1 - cos ß)</p><p></p><p>ß = cant angle</p><p></p><p></p><p></p><p>[/ QUOTE ]</p><p></p><p>Do you have a derivation for these?</p><p></p><p>[ QUOTE ]</p><p></p><p>I think these formulas should be pretty accurate for the small angles we are discussing, normal cant in LR shooting should be 6º or less.</p><p></p><p></p><p>[/ QUOTE ]</p><p></p><p>If I have time, I'll see what I can do with my formulas and a small angle approximation.</p><p> </p><p>[ QUOTE ]</p><p></p><p>The sight height has no effect when you zero the scope at any distance, since you are basically converging the LOS and bore line at that range, and then compensating for drop (see images A, B and C in this article: <a href="http://www.tirofusil.com/canting01.php" target="_blank">http://www.tirofusil.com/canting01.php</a> )</p><p></p><p></p><p>[/ QUOTE ]</p><p></p><p>The effects of sight height are an offset to the zero in both the elevation and windage. It's very small and probably be neglected though. I didn't because I wanted everyone to see the accuracy when everything is taken into a ccount.</p><p> </p><p>[ QUOTE ]</p><p></p><p>When you cant the rifle you do it rotating on the LOS, so drop is the "diameter of the circle". This is normally done in target or long range shooting.</p><p></p><p></p><p>[/ QUOTE ]</p><p></p><p>I'm not sure what you mean by "drop is the diameter of the circle".</p><p> </p><p>[ QUOTE ]</p><p></p><p>The formulas Gustavo posted take this into account:</p><p></p><p>X(R)=H(R)*sin ß </p><p>Y(R)=H(R)*cos ß - Drop(R)</p><p></p><p>where H(R) is the height of bore line in relation to sight </p><p>line, as a function of range R:</p><p></p><p>H(R) = R/R0*(SH + Drop0)- SH</p><p></p><p>SH = sight height</p><p>R = range </p><p>R0 = zero range</p><p>Drop0 = drop at zero </p><p></p><p>[/ QUOTE ]</p><p></p><p>I'd just like to see the derivation for the formulas. I'll check the link you posted.</p></blockquote><p></p>
[QUOTE="JBM, post: 109656, member: 1969"] [ QUOTE ] The basic formulas we are using are: horizontal projection: X = drop*sin ß vertical projection: Y = drop*(1 - cos ß) ß = cant angle [/ QUOTE ] Do you have a derivation for these? [ QUOTE ] I think these formulas should be pretty accurate for the small angles we are discussing, normal cant in LR shooting should be 6º or less. [/ QUOTE ] If I have time, I'll see what I can do with my formulas and a small angle approximation. [ QUOTE ] The sight height has no effect when you zero the scope at any distance, since you are basically converging the LOS and bore line at that range, and then compensating for drop (see images A, B and C in this article: [url="http://www.tirofusil.com/canting01.php"]http://www.tirofusil.com/canting01.php[/url] ) [/ QUOTE ] The effects of sight height are an offset to the zero in both the elevation and windage. It's very small and probably be neglected though. I didn't because I wanted everyone to see the accuracy when everything is taken into a ccount. [ QUOTE ] When you cant the rifle you do it rotating on the LOS, so drop is the "diameter of the circle". This is normally done in target or long range shooting. [/ QUOTE ] I'm not sure what you mean by "drop is the diameter of the circle". [ QUOTE ] The formulas Gustavo posted take this into account: X(R)=H(R)*sin ß Y(R)=H(R)*cos ß - Drop(R) where H(R) is the height of bore line in relation to sight line, as a function of range R: H(R) = R/R0*(SH + Drop0)- SH SH = sight height R = range R0 = zero range Drop0 = drop at zero [/ QUOTE ] I'd just like to see the derivation for the formulas. I'll check the link you posted. [/QUOTE]
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Canting - the right answer
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