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ballistic coefficient questions . 6.5 mm bullets

 
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  #64  
Old 01-17-2013, 09:56 AM
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Re: ballistic coefficient questions . 6.5 mm bullets

Quote:
Originally Posted by Beng View Post
If the 140gr's form factor is the same as the 130gr's and assuming the .56 bc of the 130gr is correct, then the 140gr bullet would have a bc of .603.
The 130gr CEB's form factor is similar to the Berger 140gr VLD's form factor, so, if you have one of the latter at hand, just compare the 130gr CEB's ogive and boattail to the Berger's.
I'd wager the ogive is shorter than the Berger's ogive.


Ask & ye shall receive

130 CEB flanked by the 140 VLD & Hybrid.

ballistic coefficient questions . 6.5 mm bullets-cebs-vlds-2-.jpg


t
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  #65  
Old 01-17-2013, 10:54 AM
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Re: ballistic coefficient questions . 6.5 mm bullets

Great thanks Outlaw6.0

CEB 130gr
Sd=0.267
Published bc = 0.56
Bc=sd/i
i=0.267/0.56
i1=0.477

Berger 140gr vld
i1=0.471

For comparison
Hornady 140gr a-max
i1=0.493

Judging from the picture the 130gr CEB's ogive is quite a bit shorter than the Berger's.
Both bullets have long boattails with similar angle.
The CEB thus has to have a formfactor higher than the Berger's and with more difference than .006.
I doubt that the CEB' s bc is correct and averaged for sea level altitude longrange shooting.

Btw I don't like my mobile, it always sends posts I have not finished
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  #66  
Old 01-17-2013, 02:01 PM
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Re: ballistic coefficient questions . 6.5 mm bullets

Quote:
Quote:
Originally Posted by Beng View Post
Great thanks Outlaw6.0

CEB 130gr
Sd=0.267
Published bc = 0.56
Bc=sd/i
i=0.267/0.56
i1=0.477

Berger 140gr vld
i1=0.471

For comparison
Hornady 140gr a-max
i1=0.493

Judging from the picture the 130gr CEB's ogive is quite a bit shorter than the Berger's.
Both bullets have long boattails with similar angle.
The CEB thus has to have a formfactor higher than the Berger's and with more difference than .006.
I doubt that the CEB' s bc is correct and averaged for sea level altitude longrange shooting.

Btw I don't like my mobile, it always sends posts I have not finished
The ogive of the CE is actually almost the same length as the Berger. If you look closely at the pic you'll see the seal tite band then just above it you'll see the driving band which runs about .100 up the bullet. The driving band tapers form about .262 to .259 Just above the driving band you'll see a shiny band which is the bore rider which runs about another .100 up the barrel. The bore rider maintains at .259 which is about .005 narrower than the Berger's bearing surface. The Berger's nose is narrower and changes more abruptly @ the bearing shank of the bullet. I suspect the Berger does have a higher BC (.618), especially with a higher SD but the CE probably isn't too far behind.
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  #67  
Old 01-17-2013, 03:06 PM
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Re: ballistic coefficient questions . 6.5 mm bullets

Am I about right with this?




I don't want to bad mouth the CEB's in any way, pls don't misunderstand my comments. They are propably the ballisticly best monolithic hunting bullets readily available. To me some of their form factors seem to be a bit too high to be true though. Litz measurements seem to agree there.
They have a very smooth transition from ogive to "bearing surface", so maybe I'm just not able to see the lengths of their ogives on pictures.
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  #68  
Old 01-17-2013, 03:13 PM
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Re: ballistic coefficient questions . 6.5 mm bullets

Quote:
Originally Posted by Beng View Post
Am I about right with this?




I don't want to bad mouth the CEB's in any way, pls don't misunderstand my comments. They are propably the ballisticly best monolithic hunting bullets readily available. To me some of their form factors seem to be a bit too high to be true though. Litz measurements seem to agree there.
They have a very smooth transition from ogive to "bearing surface", so maybe I'm just not able to see the lengths of their ogives on pictures.


Beng, you're not bad mouthing at all, I enjoy an in depth discussion. Here's a pic to help you out:

ballistic coefficient questions . 6.5 mm bullets-ceb-bullet-design.png


T
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  #69  
Old 01-17-2013, 03:23 PM
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Re: ballistic coefficient questions . 6.5 mm bullets

No, I didn't consider your comments as bad mouthing at all. I was just making some clarifications and observations.

You got the seal tite band and end of driving band correct. The start of ogive is farther down the bullet. You can see the transition between the ogive and bore rider by the difference in color shade.

The Berger has a narrower nose, but the CE's transition is smoother and it has a narrower bore riding shank. Not really sure how all that plays out in form factor but as I hold and look at the CE 130, it appears to be a sleek bullet. The seal tie band is a bit of a bump on the surface, but not sure how it would affect laminar flow as it is fairly far aft. Alos the transition from bore rider to driving band might disturb laminar flow as well? not sure.
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  #70  
Old 01-17-2013, 05:22 PM
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Re: ballistic coefficient questions . 6.5 mm bullets

The point where it gets a bit darker in color then, about a third of a caliber above my db mark.
Well, I underestimated the ogive's length quite a bit, I've always had problems with finding the point of transition with tangent ogives.
I can't make a comment on driving band, seal tite band &c, I just don't know how to figure those in.
Yes, the 130gr CEB is onehell of a sleek looking bullet, I still don't think it's in the Berger's league, but I'd have to guess blindly on the real form factor and even at .5 it would be a superbly low drag hunting bullet.
I'd love to see more of the CEBs being measured by Bryan Lith, those three that have been measured didn't do that good. Especially the .338 and .264 bullets look much better than the measured ones though.

I'll order some and try them in a 6.5x55 project I'm working on, the hog's won't like them I think
A waste though to use them at short range.
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