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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Bullet stability
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<blockquote data-quote="MajorSpittle" data-source="post: 1952143" data-attributes="member: 53101"><p>I think that the only relevance that "length of plastic ballistic tip (Drag coefficient and CG parameters)" has is in calculating the center of gravity of the bullet. Basically a bullet with a better center of gravity (more forward) has a better chance of launching with better SD "less wobble" and it will slightly reduce the distance the tip is from the CG so there is less leverage against the CG per X amount of SD. As far as Drag coefficient it doesn't matter what the tip is made of because air pressure will act upon the surface the same and that air pressure is what the SG has to over come.</p><p></p><p>So I would go with Berger while keeping in mind that basically both stability calculators are based on; you need X amount of RPMs in a bullet of X diameter that is X weight to overcome X amount of off axis force on a surface X amount of distance from the CG. </p><p></p><p>Berger uses a static "X amount of off axis force per Air Pressure"</p><p></p><p>JBM uses a dynamic "X amount of off axis force per Air Pressure" because it attempts to account for leverage with distance to CG and could possibly increase the RPMs needed with longer poly tipped bullets due to resistance being farther from the CG.</p><p></p><p>But I am just guessing and have been drinking a lot tonight.</p></blockquote><p></p>
[QUOTE="MajorSpittle, post: 1952143, member: 53101"] I think that the only relevance that "length of plastic ballistic tip (Drag coefficient and CG parameters)" has is in calculating the center of gravity of the bullet. Basically a bullet with a better center of gravity (more forward) has a better chance of launching with better SD "less wobble" and it will slightly reduce the distance the tip is from the CG so there is less leverage against the CG per X amount of SD. As far as Drag coefficient it doesn't matter what the tip is made of because air pressure will act upon the surface the same and that air pressure is what the SG has to over come. So I would go with Berger while keeping in mind that basically both stability calculators are based on; you need X amount of RPMs in a bullet of X diameter that is X weight to overcome X amount of off axis force on a surface X amount of distance from the CG. Berger uses a static "X amount of off axis force per Air Pressure" JBM uses a dynamic "X amount of off axis force per Air Pressure" because it attempts to account for leverage with distance to CG and could possibly increase the RPMs needed with longer poly tipped bullets due to resistance being farther from the CG. But I am just guessing and have been drinking a lot tonight. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Bullet stability
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