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ballistic coefficient questions . 6.5 mm bullets

 
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  #78  
Old 01-18-2013, 06:34 AM
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Re: ballistic coefficient questions . 6.5 mm bullets

Quote:
Originally Posted by Edd View Post
I agree, I only use one load per cartridge. I sometimes switch bullets but I get rid of the old ones when I do.

You do know Cutting Edge makes them without the hole drilled in the nose?
No I didn't. I'll check it out.

I didn't realize the BC changed so much with velocity.
Ignorance sure is bliss,

So, now I'm confused again, I known, regular occurance.

But, as I understand it the 6.5 Cm IS proven to be reliably accurate to 1000 yards / meters with the 140 gr A Max with an 8" twist . And it seems to have a similar BC as the 130 CEB. So wouldn't the 130 CE work well at 6.5 Cm / 260 Rem/ 6.5x47/6.5 Sweede velocities. ??
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  #79  
Old 01-18-2013, 07:43 AM
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Re: ballistic coefficient questions . 6.5 mm bullets

G1 bc's are very velocity sensitive, but that is because of the model used to calculate a G1 bc. G7 bc's are much more stable because the model used is closer in form to modern streamlined bullets. Bryan Litz has written some pretty informative stuff on that subject, if you care to have your head spin a bit.

The problem, as I see it, with the CE 130g bullet is two fold:

First, most factory 6.5's come with a 9 twist. That means, if I want to shoot this bullet, I have to have a custom barrel. Now, it is said that the 140 class VLD's also require an 8 twist. However, I have found them to shoot very well in my 9 twist rifles. Go figure. The only way I found that out was to try them. However, at 3-4x the cost of Bergers or AMAX's, I am reluctant to experiment with these bullets. I might feel differently if there were a gain in performance to be had, which brings me to my second point...

Secondly, even if we accept CE's bc numbers, which appear almost certain to be optimistic, the CE 130g bullet will not shoot as flat as the conventional 140 VLD's at long range. Yes, the 130 may be able to be launched a bit faster, but that difference won't hold up as the range increases. So, in the balance of bc/velocity, we have a tie, at best.

Yes, the CE is more likely to perform better than the VLD's at shorter ranges where the impact velocity is still high. But, there are already bullets like Barnes, GMX, and E-Tip that do this just as well and at less expense.

To me, the CE bullets in the smaller calibers have two possible advantages over other bullet designs:

1. They offer a one bullet solution for close and long range shooting. However, close range terminal performance is still gained at the expense of long range ballistic performance. The loss of long range ballistic performace will just be smaller than with other mono metal bullets.

2. If you have a rifle/cartridge case combination that is capable of driving conventional 6.5mm bullets fast enough to make them come apart, the 130 CEB is the best of all possible worlds for you. Its monometal construction will eliminate bullet blow up in flight and give good terminal performance on impact and it will do that with the best bc obtainable in a monometal bullet.

The kicker, IMO, is that neither of the possible benefits of the CE bullets are going to be realized at the velocities produced by any 6.5 cartridge from the .264WM on down. Especially with the short action 6.5's, there is no advantage at all to shooting this bullet.

So, unless you are shooting a 6.5STW or a 6.5-300 Wby, I don't see an advantage to these bullets. And, for 3x the price of Bergers, you are going to have to show me a pretty decisive advantage to even interest me in shooting them.

For .338 and up, these bullets offer performance increases that cannot be had in other bullets. It doesn't look to me like those benefits translate to the lighter calibers, however.
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  #80  
Old 01-18-2013, 08:33 AM
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Re: ballistic coefficient questions . 6.5 mm bullets

They will work to a certain range depending on the necessary terminal velocity and the muzzle velocity.
If you want to shoot game at a mile, it will propably not work that good.
To 500yard it should be ok, farther and on heavy game i'd use a bigger caliber magnum.
But that's just me.
The game I'm hunting doesn't weigh more than 200lbs also, most boars come in at about 100lbs, the young tasty oned atleast.
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  #81  
Old 01-18-2013, 09:00 AM
Edd Edd is offline
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Re: ballistic coefficient questions . 6.5 mm bullets

Quote:
Originally Posted by Cold Trigger Finger View Post
No I didn't. I'll check it out.

I didn't realize the BC changed so much with velocity.
Ignorance sure is bliss,

So, now I'm confused again, I known, regular occurance.

But, as I understand it the 6.5 Cm IS proven to be reliably accurate to 1000 yards / meters with the 140 gr A Max with an 8" twist . And it seems to have a similar BC as the 130 CEB. So wouldn't the 130 CE work well at 6.5 Cm / 260 Rem/ 6.5x47/6.5 Sweede velocities. ??
Look at their match/tactical bullets instead of the match/tactical/hunting bullets.

One thing you need to consider with Cutting Edge and Berger bullets in a Creedmoor is overall length. A SAAMI Creedmoor chamber has .200 freebore. Your magazine can be too short to get the Bergers against the lands and to keep the Cutting Edge sealtite band out of the case neck. That much freebore may also keep the bore rider on the Cutting Edge from parking in the bore.
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  #82  
Old 01-18-2013, 09:38 AM
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Re: ballistic coefficient questions . 6.5 mm bullets

Quote:
Originally Posted by Beng View Post
They will work to a certain range depending on the necessary terminal velocity and the muzzle velocity.
If you want to shoot game at a mile, it will propably not work that good.
To 500yard it should be ok, farther and on heavy game i'd use a bigger caliber magnum.
But that's just me.
The game I'm hunting doesn't weigh more than 200lbs also, most boars come in at about 100lbs, the young tasty oned atleast.
Basically, what I am getting at is that the smaller caliber CE's seem to pretty much be niche bullets, that is to say that they only offer an advantage over more conventional bullets in a very narrow set of conditions.

To be fair, of course, I also have to admit that this is how it looks from an armchair perspective. If someone comes up with real world data that shows otherwise, I would be forced to retract what I have said so far.

Generally, I don't see an advantage to these bullets under most circumstances and certainly not within the circumstances you mentioned. I am not knocking these bullets, per se. I just don't see a compelling reason to run out and buy them. The bullets I already have will outperform them.

That's all I am sayin'. Other than that, different strokes for different folks, as they say...
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  #83  
Old 01-18-2013, 10:06 AM
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Join Date: Sep 2011
Location: Germany
Posts: 125
Re: ballistic coefficient questions . 6.5 mm bullets

Most modern hunting bullets work, it's just a question of preference which one you use.
I'm curious how they perform and one guy on whoms lease I hunt requires me to use nonlead bullets, that's sufficient excuse to use something new and unusual for me.
I like experimenting with new bullets.
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  #84  
Old 01-18-2013, 10:26 AM
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Join Date: Dec 2009
Posts: 850
Re: ballistic coefficient questions . 6.5 mm bullets

The no lead requirement is an angle that makes perfect sense and one that, to be honest, I keep forgetting about. If one is restricted to no lead bullets only, it is always nice to have additional options.

In general, I think the CE bullet design is pretty darn interesting, even intriguing. I recently bought some of the 300g .375 CE's to try in my H&H. In that caliber, even if the bc numbers are optomistic, there is still nothing in the same performance class for that case capacity. For me, that easily justifies the cost. If I want to plink, I will use something else.

In the .338 diameter, the potential performance offered by the 225g and 250g bullets looks to me to be capable of boosting the performance of the smaller cased .338's considerably. That also has my interest.

In the smaller diameters, I might be tempted to use them if I wanted to use a large case/high velocity rifle to take on heavier game than would be attempted with a conventional bullet. A 130g 6.5mm CE doing 3500 fps or so might be pretty interesting.
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