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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Canting - the right answer
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<blockquote data-quote="TiroFijo" data-source="post: 109648" data-attributes="member: 974"><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>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>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>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>But when you have a hunting rifle you don't normally change the scope's settings, so you may take a shot at 400 m even if your zero is 200 m using holdovers. In this case the angle between LOS and bore line corresponds to the 200 m zero and the effect of canting would be smaller than if the rifle was zeroed at 500. The sight height does have an effect in this case. </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></blockquote><p></p>
[QUOTE="TiroFijo, post: 109648, member: 974"] The basic formulas we are using are: horizontal projection: X = drop*sin ß vertical projection: Y = drop*(1 - cos ß) ß = cant angle 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. 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] ) 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. But when you have a hunting rifle you don't normally change the scope's settings, so you may take a shot at 400 m even if your zero is 200 m using holdovers. In this case the angle between LOS and bore line corresponds to the 200 m zero and the effect of canting would be smaller than if the rifle was zeroed at 500. The sight height does have an effect in this case. 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]
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Canting - the right answer
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