No, you don't need "valid BC numbers" to kill big game at 400 yards--which was the point of my previous post.
Other "inputs" easily make as much or more difference, including height of the reticle over the bore, altitude and temperature. I know this from shooting quite a bit beyond 100-200 yards with various rifles.
John, I respect you - well - about as much as it is possible to respect a man, having bought most all your books, read every magazine article of yours I've ever found, and learned so much from you over the years. So please just bear with me a bit on this, and don't go crushing the curiosity you have done a lot to inspire:
I know you don't need "valid BC numbers" to kill game at 400 yards (and
you know that is not what I wrote above). I have done so, with and without valid BC numbers. But you presented a specific example comparing the flight path of the .270 Win and .308 Win, concluding their wind drift and trajectory are within 2" at 400 yards. There are two ways to draw this conclusion. The first is actual shooting of 400 yard groups, but we are now talking about a difference of only 1/2 MOA between the centroid of two groups, which for many of us is within the "noise level" of our shooting skill, and of course we would need both rifles to be very accurate to even be able to discern the centroid differences. The second way would be to run the numbers in a ballistics program. The former method has the referenced limitations. The latter requires valid ballistics coefficients as an input variable (along with the others you mentioned, but we must assume those variables are held constant in any reasonable comparison).
That's all I said.
It is perfectly OK for me and others to be curious about the BC of this particular bullet, and that curiosity does not warrant beratement, especially not from a man who has been such an incredible mentor and monumentally contributing mind to the body of knowledge that we only half-jokingly refer to as Rifle Looneyism.
Being curious about the BC of this bullet has nothing to do with whether or not I understand that particular parameter's contribution to killing game at reasonable hunting ranges is trivial. Knowing things like that is FUN, and adds to the enjoyment of our passion.
For the record, I understand that the BC difference between the .525 ogive 115 grain .257 Nosler Partition and that of its "parent" bullet is trivial to killing game effectively within 400 yards. But I would much rather know what that BC difference is than to remain ignorant of it. And there's nothing wrong with that.
I am also very interested in how this bullet performs for others here on this thread, and since it's kind of a one-off bullet, thought this would be a nice place to post those results. When I get a chance to run it in my Roberts I'll share what I learn too.
Most Respectfully,
Rex
