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Hunting
Long Range Hunting & Shooting
SD and extreme spread?
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<blockquote data-quote="Doom2" data-source="post: 3062890" data-attributes="member: 108323"><p>It often seems to be overlooked that trying to compare 100yd group dispersion with chronograph data including SD and ES is not practical. The flight time to 100yds of most centerfire cartridges is so short that vertical dispersion is minimal. In the case of a 69gr SMK it requires about a 100 fps to move the vertical POI by about 0.2" or one bullet diameter. In the case of a 168 SMK (308) its about 130 fps to move the POI by about 0.3" or one bullet diameter. This essentially means that the dispersion in groups at 100 yds is a function of factors outside of velocity and incremental charge weight and is predominately a function of barrel harmonics and chamber/cartridge/barrel interface.</p><p></p><p>As for groups improving at distance that is observed but to the best of my knowledge is more related to shooter and small sample sizes. The trajectory of the bullets require some external force to change the path.</p></blockquote><p></p>
[QUOTE="Doom2, post: 3062890, member: 108323"] It often seems to be overlooked that trying to compare 100yd group dispersion with chronograph data including SD and ES is not practical. The flight time to 100yds of most centerfire cartridges is so short that vertical dispersion is minimal. In the case of a 69gr SMK it requires about a 100 fps to move the vertical POI by about 0.2" or one bullet diameter. In the case of a 168 SMK (308) its about 130 fps to move the POI by about 0.3" or one bullet diameter. This essentially means that the dispersion in groups at 100 yds is a function of factors outside of velocity and incremental charge weight and is predominately a function of barrel harmonics and chamber/cartridge/barrel interface. As for groups improving at distance that is observed but to the best of my knowledge is more related to shooter and small sample sizes. The trajectory of the bullets require some external force to change the path. [/QUOTE]
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