Comments on: Coefficient Conundrum: G1 vs. G7, Which BC Should You Use

By: Rodney

Rodney — Sun, 26 Jul 2015 23:26:31 +0000

It should be noted that while the G7 profile will in general fit boat tail bullets better when using a simplistic ballistics system which only fits bullets with a single coefficient, systems like Sierra Bullets Infinity which profile bullets with multiple coefficients at different speeds will results in a better fit than a single coefficients regardless of the drag model. Drag coefficients are all speed sensitive, even G7, (hence why the drag curves even exist in the first place).

The G1 through G7 drag functions are simply a curve that fits one particular bullet, and the coefficients are an adjustment factor to try and make the curve fit a specific different bullet. Systems like Infinity allow the curve to be fit in segments to increase the accuracy of the fit at varying velocities.

By: JPeelen

JPeelen — Mon, 28 Jul 2014 18:35:19 +0000

I hope many shooters will follow Bryan Litz’s advice.

A reason for the frequent use of G1 (which originates from French naval projectiles of the 19th century) in my view is that it lets projectile ballistics look better. If you base your BC on short range (high velocity) measurements, the G1 curve shape will show a lower drag at the longer ranges. This may look attractive in catalogues, but is too optimistic compared to actual measured range data. For modern slender bullets G7 always results in more realistic data.

By: JPeelen

JPeelen — Sun, 27 Jul 2014 18:31:47 +0000

I hope that many shooters will follow Bryan Litz’s recommendation.

I think one of the reasons G1 is still used is that it makes bullet’s ballistics look better. Especially when you base BC on short range velocity measurements. Due to its curve shape, the G1 model then shows drag values at longer ranges that are way too optimistic. This is good for factory catalogues, but on the range only the real aerodynamics count. For slender bullets G7 is always closer to reality.