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Drag Functions in Ballistic software What is it???

Re: Drag Functions in Ballistic software What is it???

I'm glad you asked this question...haha I was actually just thinking about that today. My ballistic program lets me choose between G1, G2, G3 etc...and I have no idea what the differences are...
 
Re: Drag Functions in Ballistic software What is it???

The best explanation available is Bryan Litz's book "Applied Ballistics For Long Range Shooting."

I would highly recomend it to anyone serious about shooting.

Basically, they are different models of determining ballistic coefficients (BC). The G7 conforms best to long range rifle projectiles...the caveat is that most (if not all) ballistics programs only include G1 data.

Most bullet manufacturers only give G1 datum as well. Therefor, unless you know the G7, it is best to use G1.
 
Re: Drag Functions in Ballistic software What is it???

But to actually answer the question - BC (Ballistic Coefficient) of the bullet (or other projectile) relates to Drag Coefficient of that projectile. Obviously projectile shape (e.g. round nose, pointed, flat base, bottom tail...) impacts drag. There are several "standard" projectile shapes for which those coefficients were computed (so G1, G2,..., G7, ...). G1 is for projectiles that look like an old pistol round-nose bullet. G7 is for projectiles that look like Lapua Scenar bullet. This is why for long-range shooting (which involves Scenar-like bullets and not 45ACP FMJ ones) G7 BC reflects the bullet shape and its associated drag better.

Now buy and enjoy Bryan Litz's book!
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Re: Drag Functions in Ballistic software What is it???

g1g7standardprojos.jpg

Pick the one that most resembles your bullet.

G1 actually was written to model 19th Century artillery rounds.

Somebody invents a new Gee model about every other week but I wouldn't get wrapped around the axle about them until some manufacturer starts listing that Gee in their data.