Big_John Wrote:Well.... good point at the speed of sound increases with altitude..... 1,500@ at 5k feet.....
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BJ:
Not really sure what you want out of all of this. The longer bullets are more capable of higher BC's because there is enough room on them to streamline their design. Pay back is that they are higher only in a narrow velocity band. BC's change as velocity changes. And the longer bullets suck up powder space which means they are so slow that they will probably never get the BC that is hyped on them at Grendel velocities.
BC doesn't correlate to accuracy either. You are buying good things with them, if you can get them to the speeds they were designed to be most efficient. Faster to the target means you can make more mistakes in wind doping and get away with them. Also, for guys who do PRC on unknown distance ranges where they have to estimate range, faster means flatter trajectory which means more danger space and the shooter can make more mistakes in range estimation and get away with them. Just note that this assumes the load and bullet you are using is capable of holding the target size at those distances. Missing with a high BC bullet doesn't do you any more good than the same with a low BC bullet.
I am sure it gets to a point where you are losing so much powder space in return for bullet length (an maybe higher BC), that a bullet of less BC going a lot faster will also go farther. Not sure where it is with your bullets.
5K feet is an elevation where you sure will see a improvement in effective range and you will need to come down on elevation compared to sea level. The guys here having the best performance at long ranges with the relatively low velocity Grendel are shooting at 5K and over.
I think what we are all getting at is that finding a bullet that does what you want is more important than shooting a bullet with a higher BC.
LR-55