Question about bc's and form factors

[mooger31]

How do you know what form factor a bullet manufacturer uses. Currently trying to figure out what form factor nosler uses in their own reloading manual. Thanks in advance.

 

[Juster]

If you have the BC from the website, ff=sd/bc, sd from the diameter and weight.

 

[mooger31]

If you have the BC from the website, ff=sd/bc, sd from the diameter and weight.

Thanks for the info. But I was wondering if nosler prints the g7 bc's or if the print g1 bc's? And if they need to be converted to a g7 form factor.

 

[Juster]

You can have a G1 Form factor and a G7 Form Factor.That formula is fine for G1, which Nosler uses http://www.nosler.com/Bullets/Partition.aspx . SD is lb/in[SUP]2.[/SUP]

 

[AlexF]

How do you know what form factor a bullet manufacturer uses. Currently trying to figure out what form factor nosler uses in their own reloading manual. Thanks in advance.

Do you have a copy of Brian Litz's "Applied Ballistics for Long Range Shooting"?
From Litz's data, Nosler Ballistic Tip and Accubond have a 1.10-1.20 form factor while Nosler Partition have a 1.25-1.35 form factor
Currently all Nosler bullets are tangent ogive but any new Nolser bullet with a secant ogive should get a 15% better form factor.

Alex

 

[mooger31]

Thanks alot guys. Really appreciate the quick responses.

 

[Juster]

I was just looking at my formula for form factor:

bcx = (0.00045 / bc) - 0.00006;
form factor=(weight / 7000.0) / ((bcx+1) * bc * bulletDiameter * bulletDiameter);

bulletDiameter inches, weight grains

 

[.284]

I think that nosler's bc's are pretty optimistic for most of their bullets so your result may be a bit off using that formula.