B.C. IM CONFUSED ON THE 6.5 CALIBER

[JimD]

.

I'm not sure exactly what this thread is supposed to be about, from the OP's p.o.v.
- he mentions ballistic coefficient first
- but the essence of the question seems to be about wind drift

Anyway... to the extent that it is about wind drift...

A long time ago, I really delved into this subject, looking for empirically derived information on "wind bucking", variables that effect why one bullet gets "pushed around" more than another, etc.
I satisfied myself that there are two, and only two, variables that effect wind drift as regards the rifle and the bullet:
- velocity of the bullet
- ballistic coefficient
(of the two, velocity has the greater influence)

There are, of course a slew of variables that might affect your ultimate wind correction: distance to target, velocity of the wind, direction of the wind, temperature, elevation, etc.
But these are things that we can only deal with, not control.

The only things we can control are velocity and BC.

Best regards,

JimD

.

 

[Susquatch]

.

I'm not sure exactly what this thread is supposed to be about - from the OP's p.o.v.
- he mentions ballistic coefficient first
- but the essence of the question seems to be about wind drift

Anyway... to the extent that it is about wind drift...

A long time ago, I really delved into this subject, looking for empirically derived information on "wind bucking", variables that effect why one bullet gets "pushed around" more than another, etc.
I satisfied myself that there are two, and only two, variables that effect wind drift as regards the rifle and the bullet:
- velocity of the bullet
- ballistic coefficient
(of the two, velocity has the greater influence)

There are, of course a slew of variables that might affect your ultimate wind correction: distance to target, velocity of the wind, direction of the wind, temperature, elevation, etc.
But these are things that we can only deal with, not control.

The only things we can control are velocity and BC.

Best regards,

JimD

.

In the third post, the OP clarifies his question as follows. "I guess what IM trying to solve is how the 6.5 scores higher BC than .308. Until you get in the 200 grain weight class. I am comparing calibers and still the question marks abound".

That probably explains your question.

But to your point, and to the extent that the question is about wind drift, I agree that velocity is more important than BC.

I would only try to help overall understanding of the whole issue by pointing out that both are really about time. Time is the essence of the whole matter. The longer the time that the bullet is in flight, the more it will drift. Higher velocity means less time. Same goes for BC. Anything we can do reduce the time that the bullet is in flight reduces wind drift and drop.

 

[JimD]

.

In the third post, the OP clarifies his question as follows. "I guess what IM trying to solve is how the 6.5 scores higher BC than .308. Until you get in the 200 grain weight class. I am comparing calibers and still the question marks abound".

That probably explains your question.

But to your point, and to the extent that the question is about wind drift, I agree that velocity is more important than BC.

I would only try to help overall understanding of the whole issue by pointing out that both are really about time. Time is the essence of the whole matter. The longer the time that the bullet is in flight, the more it will drift. Higher velocity means less time. Same goes for BC. Anything we can do reduce the time that the bullet is in flight reduces wind drift and drop.

Thanks Susquatch.
For your OP clarification, and "bottom lining" my post.

To me (regarding this issue), velocity just screamed "time of flight", but...
yeah... indeed I never said it in so many words.

Thanks for putting a little finer point on the issue than I did.

JimD

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[Antonio m]

I read, calculated and pontificate aerodynamic bullet performance myself.
As I see it , it is clear as mud.
It is about marketing, firstly, imo.
It really depends on industry push, the .264 dia bullet has no magic ingredient to fly better than others.
It is becoming more evident as more vld bullets become available and rifles to suit.
I remember the .284 bullet being touted as the ideal dia. in the 70's and 80's.
It is quite amazing watching the Creedmoor being sponsored industry wide as an all around chambering, in reality( mine) it is a fairly pedestrian choice and underperforms on Elk sized animals unless a tough tenacious bullet is used at moderate distances.
It needs a larger case capacity , like the .264 Win to be called decent Elk round.
The .308 in a long ,sleek, heavy , fast twist bullet will work better than any .264,imo.

 

[wbm]

Decent elk round? 50 BMG. Quit messing around with "girly cartridges" like 6.5 and 7.62. Get the job done right.

 

[Steelflight]

So I thank you for all the answers. It helps. B.c. and wind drift are held together is how I understand it. Winddrift is a part of how well a b.c. score is made.

With the mathmatics given it has been cleared up. You guys have been a great help