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swift bullet?

 
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  #1  
Old 01-05-2013, 12:01 AM
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swift bullet?

Just trying to figure out why the scirocco 2 is so high in bc. The 6.5 130 grn accubond is .488 and the swift 130 is .571. Why is this? any ideas? Thanks Rob.
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  #2  
Old 01-05-2013, 12:05 AM
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Re: swift bullet?

Quote:
Originally Posted by Stick View Post
Just trying to figure out why the scirocco 2 is so high in bc. The 6.5 130 grn accubond is .488 and the swift 130 is .571. Why is this? any ideas? Thanks Rob.
Not absolutely sure on this but I think the Swift is a secant ogive and the AB is a tangent which gives the Swift a more streamlined nose.....Rich
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  #3  
Old 01-05-2013, 12:25 AM
Edd Edd is online now
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Re: swift bullet?

From another thread.............

I measured a G1 BC of .491 for that bullet. G7 BC is .251.

It's got a decent ogive design, but a poor (short and steep) boat tail for base drag reduction. Certainly not a design that could possibly produce a .571 average G1 BC. Even at 3000 fps, the G1 BC is just .515, degrading to .453 at 1500 fps.

A thick jacket for a long bullet...? Sure it makes the bullet longer, but that doesn't mean high BC. Lengthening the nose and tail will reduce drag, but lengthening the bearing surface does nothing for drag so it's irrelevant.

None of my analysis included group shooting (precision) testing so I can't comment on that. They may be extremely precise, but the BC claim is not accurate.

-Bryan
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  #4  
Old 01-05-2013, 12:47 AM
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Re: swift bullet?

Quote:
Originally Posted by Edd View Post
From another thread.............

I measured a G1 BC of .491 for that bullet. G7 BC is .251.

It's got a decent ogive design, but a poor (short and steep) boat tail for base drag reduction. Certainly not a design that could possibly produce a .571 average G1 BC. Even at 3000 fps, the G1 BC is just .515, degrading to .453 at 1500 fps.

A thick jacket for a long bullet...? Sure it makes the bullet longer, but that doesn't mean high BC. Lengthening the nose and tail will reduce drag, but lengthening the bearing surface does nothing for drag so it's irrelevant.

None of my analysis included group shooting (precision) testing so I can't comment on that. They may be extremely precise, but the BC claim is not accurate.

-Bryan
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Bryan Litz
Ballistician
Are "decent" and "secant" synonymous? Just kidding!......Rich
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  #5  
Old 01-13-2013, 03:11 PM
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Join Date: Jan 2009
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Re: swift bullet?

Stick,
I have the wonderful BS Buster investment book APPLIED BALLISTICS FOR LONG-RANGE SHOOTING, it is a cheap way to cut thru the crap.[Much cheaper to read about Bryan's work than have to load, shoot and decipher the data myself] Ref. page 420 on this 130 gr Scirocco. I bought some from Swift in their booth at the DSC Convention a few years back, kind of like a buxom blonde butt with a flat arse.
I am hoping Bryan will offer online updates to his book.
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