Ballistic Coefficient

I don't reload(but plan to as soon as I get a rifle), but find the information facinating. What is Ballistic Coefficient? How is it relative to bullet performance? WHat factors contribute to it? Thanks for the info.

PS-I was wondering if there is a good resource(book) that discusses much of rifle shooting/reloading?? I want to learn.

Most any of the relaoding manuals has answers to these questions and more. The Speer Manual is a good one, for example, and has very good articles covering ballistics, sectional density, ballistic coefficient, etc. but so do most of the other manuals.

The ballistic coefficient (BC) of a small-arms bullet is a figure that shows how well it holds its velocity, energy, trajectory, etc, down-range — as compared with a thoroughly studied standard projectile (typically the G1 artillery projectile).

The three factors that determine a bullet's BC are its diameter, its weight, and its shape (its "form"). Its diameter and weight establish its sectional density. Its sectional density and a "form factor" determine its sectional density.

Using the arbitrary figure 1.000 for the G1, the BC of the 75-grain Hornady .224 A-Max — 0.440 — suggests that this particular .224 bullet plows through the air about 44% percent as efficiently as the G1 projectile does.

But the only projectile that sheds velocity in the same general manner as the G1 is the G1 — no other. So a small-arms bullet cleaves the air at some percentage like the G1 along some parts of its trajectory, but at some other percentage like the G1 at other points.

So the comparison between a small-arms bullet and the standard projectile is always inexact but good enough for practical comparisons between one small-arms bullet and another. And a few of the newest rifle bullets have BCs higher than 1.000. They're even more aerodynamic than the G1!

Well stated Ken. I don't mean to correct what you wrote, but if someone read that "sectional density and form factor combine to determine sectional density", they may be confused. What he meant to say was that "sectional density and form factor combine to determine ballistic coefficient". It's interesting to note the relationship between ballistic coefficient and veloctiy on some bullets and how one will change in relationship to the other.

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Dan AZ www.huntandlodge.com

Thanks, Dan!
You're absolutely right — that's what I meant to say, and I'm glad you caught my mistake and corrected it.
I can't figure out which is worse — thinking faster than I can type or typing faster than I can think. Tried both. Can't tell.