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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Super Fast Twist Barrels for Hammer Bullets
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<blockquote data-quote="RockyMtnMT" data-source="post: 2884057" data-attributes="member: 7999"><p>There is a point where bullet length hits about 6x caliber in length. At this point dynamic stability becomes very difficult and sometimes you just can't twist enough to overcome it. Particularly the higher the velocity gets. Technically all bullets have a speed limit where they will become dynamically unstable. Some bullets should have deployable fins. When we worked with [USER=30671]@HARPERC[/USER] 's 6.5 Ultracat the goal was to run a bullet around 160g. We designed a bullet that was pushing 2" long and about 155g. It was pushing a stability factor over 2.0sg calculated by the Miller formula. It shot well until we hit 3200 fps where it started swapping ends inside 200y. We have seen this happen with bullets that maintain sub half moa out to 1300y and then start tumbling even though they are very ballistically stable and still 800 fps above the sound barrier.</p></blockquote><p></p>
[QUOTE="RockyMtnMT, post: 2884057, member: 7999"] There is a point where bullet length hits about 6x caliber in length. At this point dynamic stability becomes very difficult and sometimes you just can't twist enough to overcome it. Particularly the higher the velocity gets. Technically all bullets have a speed limit where they will become dynamically unstable. Some bullets should have deployable fins. When we worked with [USER=30671]@HARPERC[/USER] 's 6.5 Ultracat the goal was to run a bullet around 160g. We designed a bullet that was pushing 2" long and about 155g. It was pushing a stability factor over 2.0sg calculated by the Miller formula. It shot well until we hit 3200 fps where it started swapping ends inside 200y. We have seen this happen with bullets that maintain sub half moa out to 1300y and then start tumbling even though they are very ballistically stable and still 800 fps above the sound barrier. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Super Fast Twist Barrels for Hammer Bullets
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