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G1 differences ?


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Sorry if this has been covered but ballistic shows the G1 Bc as .550 for the 140amax whereas hornady them selves use .585 (g1) so how do I change ballistic or are they right?

 

What's to do?

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Sorry if this has been covered but ballistic shows the G1 Bc as .550 for the 140amax whereas hornady them selves use .585 (g1) so how do I change ballistic or are they right?

 

What's to do?

There is probably more than one way to calculate BC,and I believe it varies in the same bullet at different velocities.Different manufacturers might legitimately use this,selectively-but they don't 'put it on the tin'(ie which BC calculation they are using...)

At a pinch,as you are dealing with the same bullet,you might use both and average(.567 ish) Less than .02 'error' won't be the biggest factor in the overall picture.

george

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0.585 is. the average to 1000yards ( ie the BC will be a little low at higher velocities and a touch high as it slows) you'll get better results by getting a calculator that will take a multi bc or a g7 it depends how far you want to shoot if under 5-600 you'll not be far off with a single g1 figure, over that and the difference between reality and the program will start to show. as with any program *#%@ in *&%# out.

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thanks all ,

 

any ideas on how to change it now then ?

Absolutely! The G7 is based on 'subtleties' like a pointed nose and a boat tail (G1 isn't!)and this much reduces 'bullet speed' differences in quoted BC,which begin to matter beyond say 500 yards. (for 155 berger vld at3000 and 2000 fps,the differences in BC for G1 are 14%,for G7 3%,( G1 .465 and .422; G7 .228 and .223).If you can use a G7 program,and of course G7 BC's,as Rabbit Fingers advises.Bryan Litz too,and he's the man!

george

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