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Rifles, Reloading, Optics, Equipment
Reloading
Reloading Investment
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<blockquote data-quote="Kennibear" data-source="post: 874709" data-attributes="member: 51650"><p>Jachtrude</p><p></p><p>The closer in weight your bullet is to the stability limit of your rifleing twist rate the more form stable the bullet is @ long range. 22cal-55gr ideal twist is 1-14. 30cal-220gr is 1-10 etc. If you spin it too fast the bullet will lurch somewhere down range as it corrects its aerodynamic path with its spin stabilized direction. This is an over simplification of a complex subject. The lurch doesn't happen at the exact same range in the exact same amount for every shot so it causes dispersion. 308 target loads went to 168gr (an odd weight) to adjust for its 1-12 twist. Optimaly stabilized bullets adjust aerodynamicaly in a constant rate so they follow the ideal low drag point on path all the way to the target. No lurch. 556Nato went to 80gr bullets for extreme ranges to compinsate for the 1-7 twist.</p><p></p><p>Bottom line: heavy good, light bad. Heavy for caliber slugs= high BC. When the weight starts dragging the velocity down there is a comprimise. Use a ballistic program to run the "what ifs". </p><p></p><p>Hope this helps but whole books have been written about it. Can't hope to cover it here.</p></blockquote><p></p>
[QUOTE="Kennibear, post: 874709, member: 51650"] Jachtrude The closer in weight your bullet is to the stability limit of your rifleing twist rate the more form stable the bullet is @ long range. 22cal-55gr ideal twist is 1-14. 30cal-220gr is 1-10 etc. If you spin it too fast the bullet will lurch somewhere down range as it corrects its aerodynamic path with its spin stabilized direction. This is an over simplification of a complex subject. The lurch doesn't happen at the exact same range in the exact same amount for every shot so it causes dispersion. 308 target loads went to 168gr (an odd weight) to adjust for its 1-12 twist. Optimaly stabilized bullets adjust aerodynamicaly in a constant rate so they follow the ideal low drag point on path all the way to the target. No lurch. 556Nato went to 80gr bullets for extreme ranges to compinsate for the 1-7 twist. Bottom line: heavy good, light bad. Heavy for caliber slugs= high BC. When the weight starts dragging the velocity down there is a comprimise. Use a ballistic program to run the "what ifs". Hope this helps but whole books have been written about it. Can't hope to cover it here. [/QUOTE]
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