It pains me to see the extent to which you�re �dug in,� now doing anything and everything in an attempt to win an argument. You�re jumping through hoops like a circus animal trying to sweep your errors under the rug, just so you can avoid being seen as �being wrong.�
It happens. It�s OK. It�s how we learn. No need to feel shame.
I�ll skip right to the important stuff, so only the truly interested need read the details.
You began this thread saying the G1 BC of .545 Berger provided for their 115 VLD was not accurate. You showed another method and came up with a G1 BC of .559. You accused them of using poor methodology to cause the error and due to that suspected their G7 BC�s may also be inaccurate.
Since I believe you�d rather recite the entire text of
War and Peace than do any of the simple calculations which I told you to do and which prove you wrong, I have done the important one for you. Using the bullet you chose, using the exact same assumptions you used, using the exact same methodology you used, when launched at 2500 fps that bullet has an average G1 BC of .548 from the muzzle to Mach 1.2.
It is very clear to anybody who can read, that you were wrong. The large difference was caused not by Berger�s methodology, but by your choice of a very high muzzle velocity and the fundamental fact that one G1 number will only be correct at one velocity for this bullet. By now, this should be painfully obvious to everybody and I suspect, had you understood it in the first place, you never would have started this thread.
The number Berger uses is actually very close to this value. This value is the one that will be closer for the vast majority of users for that bullet. For the few shooting 378�s necked down to 6mm, your value will be closer.
That no single G1 value works for all applications with this bullet is most obviously not a fault of Berger�s methodology. It�s due to the fact the bullet follows a different curve.
That is all. Case closed. You started the thread for nothing. You were wrong. I know that is painful to admit (maybe try and prove yourself right using the Pejsa method now?) but it would be for the best.
For more details:
I picked 3200 fps for the MV
Yeah sure, by all means, just keep changing the inputs and methods until you get the answers you want. That�s how real science is done, right?
Of course JBM doesn't support Sierra's multiple BC values, so your TOF, and thus, your BC is off�..You got to use the right tool, and when dealing with Sierra's multiple BC values JBM is not it.
What in the hell are you doing using multiple BC values? Your first post, the reason you started this thread, was not to declare how accurate Sierra�s stepped BC method was. Quite the contrary. It may help confuse the issue so you can sweep the important stuff under the rug, but the rug can be lifted.
The only reason I used a Sierra bullet is because you asked for one as an example. Forget it and go back to the 115 Berger (or any other closely following the G7 curve) that you chose and the methodology you were advocating in the beginning of the thread.
You didn�t start this thread to prove using multiple G1 BC�s could give you accurate results. It is quite revealing that your final number-crunching comparison to prove you are correct did not contain the methodology you started the thread advocating as the best. That�s a concession without saying it outloud.
Every shot is subject to random variations in MV and barrel movement�.
Again, more gibberish to cover up ballistics errors. You claimed a
more accurate ballistics method. I have demonstrated it is
less accurate. You can argue that variations less than 0.5 moa are significant all day long, but most shooters and manufactures know better.
What kind of shooters do you hang out with? Have you ever actually shot something at long range? I doubt there�s a single person who tries for first round hits at 1000 or beyond who will agree with you.
I did say "at a given velocity" in that sentence and then went on to expand the definition for velocity ranges in the following sentences. How did you miss them?
If I missed them, would I have highlighted them? You said them, you just failed to apply them. That�s why I highlighted them for you.
Had Bryan tripled his testing of the 107 SMK the results would likely have been different.
Isn�t it nice how things work out so well when you can simply make up data? From what basis do you �guess� the above? Again, your first claim word for word:
a G7 form factor of 0.9972 and a G1 form factor of 0.5105. A form factor of 1.0 is the exact match for the referenced standard projectile, so Beger's #24530 is nearly a perfect form factor match to the G7 standard projectile and a poor match for the G1 standard projectile,
I gave you an example to illustrate your misunderstanding, a bullet with a i7 of near 1 and an i1 of near 0.5 that happens to follow the G1 curve better than the G7. And your response is if Bryan had kept shooting longer he would have gotten the opposite results? Very weak.
Your initial belief also suggests any bullet with an i7 closer to 1.0 than its i1 will follow the G7 curve better. This is untrue for a multitude of bullets. Bryan�s book is filled with examples.
Of course, what happens outside the convergence velocity zone affects the rest of the flight, but it can be calculated and for those of us who understand significance, useful conclusions can be made.
It sure can. Most easily and accurately by using the drag curve that matches the bullet or using stepped G1 BC�s as Sierra does�neither of which did you advocate in your first post. Your first post allowed that divergence to give you a final G1 BC that will actually be less accurate than the one provided by Berger for most users. You claimed it would be more accurate than Berger�s number. You were wrong. Proven by your own methods.
Yes, but none of them can use this .308 cal. Bullet
Purposely missing the point.
I said I don't know of any long range shooter in their right mind who would waste their time on such a load.
Then you must not know many. You see, long range shooters like to shoot. A giant magnum that burns the barrel in less than 1000 rounds is great for taking some of the guesswork out of a single shot when hunting and provides a sure kill, but it�s a poor choice if you want to shoot thousands of rounds a year�or even a month as some here do. For that, most of us have other rifles that burn a lot less powder. With that comes much lower working velocity ranges.
If Dave T was using the 240 SMK in a 30-378 Weatherby he might get it up to 2600 fps or so.
Uhm, he was using it in the .308 Winchester at a much slower velocity than that. I believe he won a national trophy out to 1000 yds with it. Maybe you wouldn�t consider him a �real long range shooter� though.
Thing is, you could lower the MV to 3200 or even 3000 and my example still works out better for the equal TOF BC.
So you think most users are using, what, 240 WBY�s instead of 6mm-378�s? Just how popular do you think rounds like that are compared with 243�s, 6mm Rem�s, etc?
I really do hope you can keep from bursting a vein and use this as a learning experience. You began a thread based upon a faulty premise. You were proved wrong. It�s OK, really. It happens.
In the end, you should now know why Berger�s G1 BC�s won�t necessarily match what you come up with if you chose a wildly different muzzle velocity. You should also understand the reason for the difference and how that has no bearing on the accuracy of the G7 numbers for bullets which follow the G7 curve relatively well. I hope you can put that to good use. Maybe try going out and actually shooting every now and then.
