243 vs 6.5 creedmore.
- Thread starter Shooterjimi
- Start date
No… it doesn’t. BC is a constant, so there really shouldn’t be a “distance” that it does matter at. It matters that you know what it is for the drop chart. It’s bullet efficiency in air, really. Which then becomes all about wind. Generally speaking, stuff starts to get real at 500 yards plus.
R.
Alberta Bigbore
CGN Regular
- Location
- Edmonton, Alberta
7mm08 would compliment your 3006
Ballistic coefficient absolutely is not a constant.
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No.
You fellers, instead of being “more right”, could have asked a question, about what was meant in the answer?
It was framed in the distances mentioned. And how it is dealt with in most ballistic calculators.
So… feel free to expound ballistic gack about how BC changes with bullet speed, and how that correlates to distance, time of flight, and so on. Try to do it in such a way that most can understand, and definitely try and show how it really matters?
Or, it can be treated as a constant, as that is how it’s plugged into most calculators, and offered by far the quicker and the simplest answer.
R.
It was framed in the distances mentioned. And how it is dealt with in most ballistic calculators.
So… feel free to expound ballistic gack about how BC changes with bullet speed, and how that correlates to distance, time of flight, and so on. Try to do it in such a way that most can understand, and definitely try and show how it really matters?
Or, it can be treated as a constant, as that is how it’s plugged into most calculators, and offered by far the quicker and the simplest answer.
R.
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No it is NOT constant ! It varies a lot with so many factors affecting it - But one being bullet speed . 
I have a .243, in a Weatherby SUB MOA topped off with a Nikon x1000. purchased it for Antelope / Coyotes... awesome rifle ! (100gr)
6.5 Creedmoore, Springfield Armory 2020 Waypoint , all carbon, topped off with a Burris PH 4-20x. Whitetail Deer, Antelope, Coyotes (143gr)
Love both guns, both very similar, recoil is minimal for both.
6.5 Creedmoore, Springfield Armory 2020 Waypoint , all carbon, topped off with a Burris PH 4-20x. Whitetail Deer, Antelope, Coyotes (143gr)
Love both guns, both very similar, recoil is minimal for both.
Considering that the OP posted the original question a little over 2 years ago and after his initial 2 posts has not been seen since, 
I'm sure he either made a decision or was just trying to get a post or 2 in as a newbie however is has genreated 131 replies and some interesting debate to say the least. 5 years from now some newbie will dig it out of the archives and viola we're back
I'm sure he either made a decision or was just trying to get a post or 2 in as a newbie however is has genreated 131 replies and some interesting debate to say the least. 5 years from now some newbie will dig it out of the archives and viola we're backI see it your simple way.
Not sure how a bullets BC is not a constant as I understand it is calculated from the properties of the bullet in relationship to a standard referance.
Of course the effect of BC on a bullets flight is going to vary with wind, velocity, temp, barometric pressure, distance, and the full moon... but isn't it a more or less consistant number that is plugged into the formula?
Willing to learn if I am missing something!
It isn’t a “real” constant as it changes throughout the flight path at different speeds/distances. You will see different BC’s quoted at different speeds/distances. Sierra, of Match King fame,
started doing this in their provided load data. Brian Litz does a great job of explaining it better, as he is an actual rocket scientist.
It is a constant as it is entered into a ballistic calculator, and really this is how the average shooter should treat it. Anything more is just being more right and getting into a small percentages of actual shooters. Then it starts to get complicated, and the answers far too long for an internet forum.
R.
Fair enough i didn't kmow that, I just assumed all bullets BC was calculated on the G7 constants and while the BC changes in flight, that it is still the G7 based BC that is important as that is the one used to compare apples and oranges and make the calculations.
The G7 is the “new” calculation based on more modern shapes/information. Again, rocket scientists explain this better. Litz wrote a book about it, and tested most of the bullets available at the time. It is certainly suggested reading, and about as exciting a fart on a windy day….
The difference between the old and new to most shooters is negligible. You can see this by loading a calculator with the old and new, and then look at the difference in bullet drops. It won’t really be enough to matter.
Use the BC given and punch it in to the calculator and shoot.
One should easily see how BC should be treated as a constant, even if it really isn’t one.
There are far more important things to worry about long long before BC being treated as a variable. And no… spin drift still isn’t one of them.
R.
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