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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
velocity in relation to barrle twist
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<blockquote data-quote="MAX" data-source="post: 31284" data-attributes="member: 184"><p>Looks like I was hanging out somewhere else for awhile. <img src="http://images/icons/wink.gif" alt="" class="fr-fic fr-dii fr-draggable " style="" /> Twist rate is the key because a) substantial change in velocity induced RPM(or S) requires gross change in velocity, which is counterproductive to the task or impossible to achieve; b) remember, GS is required because of that difference in position between CG and CP. You may gain additional GS with increased velocity, but the overturning moments grow as well. It is a fools errand. </p><p></p><p>Bullets with thin jackets are less tolerant of fast twist rates because of thin jackets(structural), and that the energy of angular momentum squares as a function of velocity like other energy calculations, in this case, RPM(S). These bullets tend to higher uniformity and accuracy, but their operational window is smaller. A smooth bore MAY stabilize one at a slower twist rate, all things being equal, but the difference is very small. So small in fact that changes in atmospheric density may undo that advantage.</p><p></p><p>I recognize the benefits of slower twists regarding accuracy, but in the main these advantages are discernable only to a small degree in very controlled circumstance, such as benchrest competition. If you wish to shoot a "55 gr bullet" and maybe leave the option open for heavier projectiles, optimize your twist for the heavies as your lighter projectiles will probably shoot about as well. It is a lot easier to deal with too much twist than not enough!</p><p></p><p> Personally, I would build the gun for the bullet and not play hopscotch.</p></blockquote><p></p>
[QUOTE="MAX, post: 31284, member: 184"] Looks like I was hanging out somewhere else for awhile. [img]images/icons/wink.gif[/img] Twist rate is the key because a) substantial change in velocity induced RPM(or S) requires gross change in velocity, which is counterproductive to the task or impossible to achieve; b) remember, GS is required because of that difference in position between CG and CP. You may gain additional GS with increased velocity, but the overturning moments grow as well. It is a fools errand. Bullets with thin jackets are less tolerant of fast twist rates because of thin jackets(structural), and that the energy of angular momentum squares as a function of velocity like other energy calculations, in this case, RPM(S). These bullets tend to higher uniformity and accuracy, but their operational window is smaller. A smooth bore MAY stabilize one at a slower twist rate, all things being equal, but the difference is very small. So small in fact that changes in atmospheric density may undo that advantage. I recognize the benefits of slower twists regarding accuracy, but in the main these advantages are discernable only to a small degree in very controlled circumstance, such as benchrest competition. If you wish to shoot a "55 gr bullet" and maybe leave the option open for heavier projectiles, optimize your twist for the heavies as your lighter projectiles will probably shoot about as well. It is a lot easier to deal with too much twist than not enough! Personally, I would build the gun for the bullet and not play hopscotch. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
velocity in relation to barrle twist
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