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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Come on bullet makers!!!
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<blockquote data-quote="groper" data-source="post: 467148" data-attributes="member: 12550"><p>Increasing velocity only has a very small effect on increasing gyroscopic stability. The primary factor effecting a bullets ability to be stabilized is its length.</p><p></p><p>The berger 210vld would have a stability factor of around 1.4xx from the 11 twist barrel and you dont want to make it any less than this or you will run into stability problems when shooting in cold conditions at low altitudes. Bullet makers must have sufficient safety margin when quoting required twists for conditions like this.</p><p></p><p>The new hornady 225gr bullet will be about as good as you will get from a 1:10twist barrel, and its only a small improvement from the 210grainers... if you want more BC than this in 30cal, you have no choice but to design a significantly longer bullet which means you have to goto a faster twist barrel.</p><p>BC is not just gained purely from increasing mass alone, its only half the story. The rest of the equation comes from the drag of the bullet which is governed by its shape. Aerodynamically efficient shapes with low drag, are very long pointy shapes and due to their volume, a pointier bullet with a longer secant nose will be lighter for the same length. so in reducing aerodynamic drag your also reducing its weight for the same length and you end up chasing your tail with regard to BC... so you very quickly run out of room for improvement which is exactly what has happened in 30cal due to the common 1:10twist barrel.</p><p></p><p>So designing a bullet for a significantly higher BC than whats already available in 30cal, just isnt feasable when your limited by a 1:10twist rate. Sure berger could design a slightly heavier bullet of 225-230grains and specify a 1:10 minimum... but dont expect the BC to be much better than their 210gr nad youll be running them a bit slower so youll loose most of what you gained anyway... go down to a 1:9 or 1:8 twist and then we can push the designs to much higher BC`s well above 0.7... same goes for alot of calibers tho... but whos gonna make bullets for barrels that dont exist, or are only able to be stabilized above 7000ft altitude and 60deg temps?</p></blockquote><p></p>
[QUOTE="groper, post: 467148, member: 12550"] Increasing velocity only has a very small effect on increasing gyroscopic stability. The primary factor effecting a bullets ability to be stabilized is its length. The berger 210vld would have a stability factor of around 1.4xx from the 11 twist barrel and you dont want to make it any less than this or you will run into stability problems when shooting in cold conditions at low altitudes. Bullet makers must have sufficient safety margin when quoting required twists for conditions like this. The new hornady 225gr bullet will be about as good as you will get from a 1:10twist barrel, and its only a small improvement from the 210grainers... if you want more BC than this in 30cal, you have no choice but to design a significantly longer bullet which means you have to goto a faster twist barrel. BC is not just gained purely from increasing mass alone, its only half the story. The rest of the equation comes from the drag of the bullet which is governed by its shape. Aerodynamically efficient shapes with low drag, are very long pointy shapes and due to their volume, a pointier bullet with a longer secant nose will be lighter for the same length. so in reducing aerodynamic drag your also reducing its weight for the same length and you end up chasing your tail with regard to BC... so you very quickly run out of room for improvement which is exactly what has happened in 30cal due to the common 1:10twist barrel. So designing a bullet for a significantly higher BC than whats already available in 30cal, just isnt feasable when your limited by a 1:10twist rate. Sure berger could design a slightly heavier bullet of 225-230grains and specify a 1:10 minimum... but dont expect the BC to be much better than their 210gr nad youll be running them a bit slower so youll loose most of what you gained anyway... go down to a 1:9 or 1:8 twist and then we can push the designs to much higher BC`s well above 0.7... same goes for alot of calibers tho... but whos gonna make bullets for barrels that dont exist, or are only able to be stabilized above 7000ft altitude and 60deg temps? [/QUOTE]
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