The Firearm Blog

Ballistics by the inch is an exhaustive ballistics experiment done by Jim Kasper, Jim Downey and Steve Meyer.

We decided to test thirteen common pistol calibers, each over a range of barrel lengths from 18″ down to 2″, and each using a variety of ammunition (most of it “premium” ammo made for self-defense purposes). In each case we fired three rounds of a given ammo at a given barrel length, recording the velocity of the bullets at 15 feet with two commercial chronographs. If we did not get two reliable readings for each of three rounds, we repeated the process until we did. Altogether we fired over 6,000 rounds of ammunition.

Thousands of rounds waiting to be shot in the name of science.

They throughly documented the results which are available on the website online and as Excel and PDF documents.

Jim Downey told me the project cost in excess of $15000, not including the man hours put into it. I asked Jim if they were going to do the same for rimfire and centerfire rifle cartridges, his reply: “Heh - we’re all too exhausted by doing this one . . . but talk to me again in a couple of years. :)”.

These guys have created a great resource that will likely settle some bets, resolve some arguments and be referenced by gun blogs, magazines and books for many years, maybe even decades!

From AccurateShooter.com

One of our readers asked “What effect does altitude have on the flight of a bullet?” The simplistic answer is that, at higher altitudes, the air is thinner (lower density), so there is less drag on the bullet. This means that the amount of bullet drop is less at any given flight distance from the muzzle. Since the force of gravity is essentially constant on the earth’s surface (for practical purposes), the bullet’s downward acceleration doesn’t change, but a bullet launched at a higher altitude is able to fly slightly farther (in the thinner air) for every increment of downward movement. Effectively, the bullet behaves as if it has a higher ballistic coefficient.

Worth a read. More here.