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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Slope/Angle ballistics (again!)
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<blockquote data-quote="Dave King" data-source="post: 21977" data-attributes="member: 3"><p>I was just now falling asleep and it came to me. I also believe I've read or was told this method at one time also.</p><p></p><p> I use the cosine of the angle against the overall correction for the entire "slope" distance rather than calculating the "base" distance and using the drop for that shorter "base" distance.</p><p></p><p> For example:</p><p></p><p> 200 yards total drop for .308 175SMK BC .507 MV of 2750. Total drop 10.1 inches, drop beyond 100 yard zero 3.5 inches, correction (scope) 1.66 MOA. 45 degree angle (cosine .707) correction amount = 10.1 * .707. Correction required is 7.14 inches for the 200 yards. About the correction required for a 170 yard "flat land" shot, 1 MOA over my "flat land" 100 yard zero.</p><p></p><p>This method invalidates the 100 yard zero as it isn't valid for an angled shot either. The 100 yard zero would be now placing the round .7 inches high and would have effectively become a 141 yard zero.</p><p></p><p> Hope this is correct, maybe I'm off in left field again.</p><p></p><p>[ 02-20-2002: Message edited by: Dave King ]</p></blockquote><p></p>
[QUOTE="Dave King, post: 21977, member: 3"] I was just now falling asleep and it came to me. I also believe I've read or was told this method at one time also. I use the cosine of the angle against the overall correction for the entire "slope" distance rather than calculating the "base" distance and using the drop for that shorter "base" distance. For example: 200 yards total drop for .308 175SMK BC .507 MV of 2750. Total drop 10.1 inches, drop beyond 100 yard zero 3.5 inches, correction (scope) 1.66 MOA. 45 degree angle (cosine .707) correction amount = 10.1 * .707. Correction required is 7.14 inches for the 200 yards. About the correction required for a 170 yard "flat land" shot, 1 MOA over my "flat land" 100 yard zero. This method invalidates the 100 yard zero as it isn't valid for an angled shot either. The 100 yard zero would be now placing the round .7 inches high and would have effectively become a 141 yard zero. Hope this is correct, maybe I'm off in left field again. [ 02-20-2002: Message edited by: Dave King ] [/QUOTE]
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Rifles, Reloading, Optics, Equipment
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Slope/Angle ballistics (again!)
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