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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Hornady ELD-X bullets
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<blockquote data-quote="Bullseye" data-source="post: 1133673" data-attributes="member: 3351"><p>Bryan, If I look at my McCoy book on page 71 where he has the meplat chart, I think you're over estimating the tip size change a lot. His graph only goes up to mach 1.8 so I would guess that at 2.5 the change of Cd vs meplat diameter gets even worse. At mach 1.8 your only talking about .030" of meplat change for a .264" diameter bullet to get a 10% increase in drag. It's probably less than that at Mach 2.5. </p><p></p><p>No offence, but radar data of actual aerodynamic bullet performance is more compelling than Bic lighter data. </p><p></p><p>If you look at those meplat curves you can also see that the meplat diameter has less and less effect on the drag as the projectile slows down to the point that at 1.3 it almost doesn't matter, at least up to the limit of the graph at .3 calibers. I think they even kind of said something like that in the FAQ.</p><p></p><p>As far as your force calculation goes you need to convert that to pressure. Concentrate .78 lbs. of force on .040" diameter of hot plastic and I'd be willing to bet it will deform. </p><p></p><p>Lastly, the way I read their FAQ and white paper they aren't saying you can't hit anything with the current AMAX. They are saying that if a BC determined over short range is used to calculate trajectories that you will have a lot of error at long range. That's why in the white paper they put the 800 yards BC's for the old AMAX. I think what they are trying to say is the new tip is a better mouse trap.</p></blockquote><p></p>
[QUOTE="Bullseye, post: 1133673, member: 3351"] Bryan, If I look at my McCoy book on page 71 where he has the meplat chart, I think you’re over estimating the tip size change a lot. His graph only goes up to mach 1.8 so I would guess that at 2.5 the change of Cd vs meplat diameter gets even worse. At mach 1.8 your only talking about .030” of meplat change for a .264” diameter bullet to get a 10% increase in drag. It’s probably less than that at Mach 2.5. No offence, but radar data of actual aerodynamic bullet performance is more compelling than Bic lighter data. If you look at those meplat curves you can also see that the meplat diameter has less and less effect on the drag as the projectile slows down to the point that at 1.3 it almost doesn’t matter, at least up to the limit of the graph at .3 calibers. I think they even kind of said something like that in the FAQ. As far as your force calculation goes you need to convert that to pressure. Concentrate .78 lbs. of force on .040” diameter of hot plastic and I’d be willing to bet it will deform. Lastly, the way I read their FAQ and white paper they aren’t saying you can’t hit anything with the current AMAX. They are saying that if a BC determined over short range is used to calculate trajectories that you will have a lot of error at long range. That’s why in the white paper they put the 800 yards BC’s for the old AMAX. I think what they are trying to say is the new tip is a better mouse trap. [/QUOTE]
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