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Topic: G1 or G7 (Read 377 times) previous topic - next topic

G1 or G7

Need guidance on which to use G1 or G7. I will be shooting Hornady 140 grain ELD match and the Hornady reloading manual lists a different BC for G1 or G7 for this bullet. I'm getting ready to put information into a ballistics calculator and don't know which I should use or if it even make a difference. Why do you need 2 different BC's . Easy to understand explanations appreciated Thanks in advance for your replies.

 

Re: G1 or G7

Reply #1
I was told G1 is old school and better for flat base bullets, shorter range.
G7 is for boat tail bullets, long range.
Whatever one you pick you will still need to verify and fine tune the calculator to real world drop.



Re: G1 or G7

Reply #4
By all means read the Accurate Shooter article.  That should settle the question.  If you plan to use a ELD-Match bullet the G-7 BC is the right one.  Good luck.

Re: G1 or G7

Reply #5
Here is the recommendation from Bryan Litz from on of his app manuals:

Drag Model - This is the drag model of your ballistic coefficient(s) (BC). Most manufacturers are going to give you a G1 ballistic coefficient and they should specify that. If you're using a long range boat tail bullet, it's actually better to use a G7 BC as the G7 model more accurately plots the trajectory of those bullets, but that doesn't mean you can enter a G1 BC then select G7 and expect to get a better calculation. You must enter G7 BC(s) if you choose G7 and you must enter G1 BC(s) if you choose G1 here. Some manufacturers will give you both a G1 BC and a G7 BC. In this case, it's probably a boattail bullet and you should prefer the G7 BC.