G1 vs G7 Drag For Long Range Bullets

Beng · #8 11-12-2012, 05:32 PM

Hi Mike
Buy "Applied Ballistics for Longrange Shooting" from Bryan Litz and read it.
All Problems solved after that.

Joe King · #9 11-13-2012, 12:24 AM

Quote:

Originally Posted by LongRangeMike

Thanks for the link but I'm a little more lost now because I'm not sure if Nosler references to G1 or G7.
I use the same B/C for both... might be the issue. I use 165 and 180 grain Nosler BST. I got the BST from the Nosler website on the bullets. And correction my Velocities were for the 165, not the 180.
B/C for 165 Grain is .475 for the BST Spitzer
B/C for 180 Grain is .507 ''....
Ballistic Tip - Nosler - Bullets, Ammunition, Rifles, Brass, Reloading Data, Hunting, Shooting, Reloading, Load Data
Not sure if those are referenced to G1 or G7... But need to know.

your G7 BC's are
165 - .227
180 - .241

G7 will give you more accurate results, to get a good drop using G1 BC's with SBT bullets of any kind you need to to model several velocities and tie them together. The more you get into VLD type bullets the more G1 will be off.

LongRangeMike · #10 11-13-2012, 03:34 PM

Joe & Others,

Thanks for the clarification and getting the G7's for me. Nosler got back to me today and suggested I use the JBM ballistics calculators to convert their G1 values to G7 especially at yardages 800+.

Now I'm much more clear on G7 vs G1 just need to put it into practice!

gebhardt02 · #11 11-13-2012, 09:36 PM

The G7 standard more closely resembles modern bullets (pointy tips and boat tails) than the G1 standard and thus the drag curves are a better match. You can get the job done with the G1 BC's but as Joe King said, you'll want to utilize the different BC's for stepped velocity boundaries. If you have a program that'll accept G7's, then you can basically just use that one number as provided above. Given the choice between the two BC values, the G7 is a better model. If you are stuck using the G1's, it'll work best to set it up with the different BC's for different velocities. And I second the recommendationon Litz's book, I have it sitting in front of me right now. Good luck.

Geb