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Rifles, Reloading, Optics, Equipment
Long Range Scopes and Other Optics
What defines 'Sight Height'?
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<blockquote data-quote="Jay Kyle" data-source="post: 304601" data-attributes="member: 347"><p>This thread is a bit old but there seems to be a lot of mystery around this measurement.</p><p> </p><p>Here's the theory - what I call the Sight Height Rule:<div style="margin-left: 20px">With respect to ballistic software, the effective distance between the LOS (Line of Sight) and the LOF (Line of Fire) should be measured at a point where the measured muzzle velocity is valid.</div> <div style="margin-left: 20px"></div><p>This is normally the "0" yard point with respect to your external ballistics software - this is an arbitrary datum point most folks assign to the end of the barrel. However muzzle velocity is measured at some distance away from the barrel and must therefore be corrected back to the muzzle. The problem with this method is that the pivot point for the LOS is located near the center of the scope, far behind the muzzle. So the LOS-LOF distance increases or decreases as you dial in more (or less) height on the scope. But since we sight in at 100 yards, and today's ballistic software doesn't account for more than a single scope height value we're stuck again.</p><p> </p><p>Now for the practical:<div style="margin-left: 20px">Best to measure the sight height at the center of the scope (LOS pivot point), and correct muzzle velocity back to that point - done.</div> <div style="margin-left: 20px"></div><p>This is the simplest and most correct way I know of to get the right values for your charts.</p><p> </p><p>Jay</p></blockquote><p></p>
[QUOTE="Jay Kyle, post: 304601, member: 347"] This thread is a bit old but there seems to be a lot of mystery around this measurement. Here's the theory - what I call the Sight Height Rule:[INDENT]With respect to ballistic software, the effective distance between the LOS (Line of Sight) and the LOF (Line of Fire) should be measured at a point where the measured muzzle velocity is valid. [/INDENT]This is normally the "0" yard point with respect to your external ballistics software - this is an arbitrary datum point most folks assign to the end of the barrel. However muzzle velocity is measured at some distance away from the barrel and must therefore be corrected back to the muzzle. The problem with this method is that the pivot point for the LOS is located near the center of the scope, far behind the muzzle. So the LOS-LOF distance increases or decreases as you dial in more (or less) height on the scope. But since we sight in at 100 yards, and today's ballistic software doesn't account for more than a single scope height value we're stuck again. Now for the practical:[INDENT]Best to measure the sight height at the center of the scope (LOS pivot point), and correct muzzle velocity back to that point - done. [/INDENT]This is the simplest and most correct way I know of to get the right values for your charts. Jay [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Long Range Scopes and Other Optics
What defines 'Sight Height'?
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