The Science of Airgun Projectiles
Once upon a time, shooters learned about the little quirks of their guns through trial and error. That method is still an excellent learning tool today, but you can certainly shorten the learning curve of how your gun will shoot, how a particular pellet performs in your gun, and a whole list of things by understanding some of the science behind shooting air guns.
In this article, let's take a look at a term that is thrown around quite a bit in the air gun world, and on the various forums. If you've never heard it before, you are bound to eventually. The term is "ballistic coefficient". 7 syllables. Two words. But what does it mean, and how does it affect you as a shooter.
First, let's define the term "ballistic coefficient". You can look it up online, or like me, you just borrow the accepted definition from the many posts on various forums when they talk about the ballistic coefficient of a certain pellet. Basically, the two words "ballistic coefficient" refer to the behavior of a projectile in the air. Another way of putting it is to say that a pellet's BC refers to how well the pellet retains its velocity in relation to the drag of the atmosphere it is moving through.
Since the diabolo-shaped pellet, one with a pinched waist, sheds velocity much faster than the solid projectiles used in rifle bullets, it is handy to know the BC of a particular brand of pellets. Pellets will shed over half of their velocity in the first 100 yards. (One definition I looked up has a pellet losing .30% to 1.3% of its velocity for each yard it goes through the air.) Knowing this ahead of time allows you to punch in the BC into a calculator, which will give you an idea of what to expect from your pellet at known distances. This is immensely useful to Field Trial competitors, as well as hunters who shoot targets at varying distances. Once you know what to expect from your projectile, you are better able to stay on target since you will know the drop of the pellet at known distances.
You can find the BC tables of most common brands of pellets by searching the internet. Here is a link to one such resource provided by individuals that host the Little Rock Airgun Show each year.
http://www.airgunexpo.com/airgundb/pelletBC.cfm
Understand that these numbers are submitted by different individuals, so bear in mind that there could be errors. However, it is a place to start. Once you've determined the BC of your pellet, you can punch in the numbers into a computer program such as Chairgun, and you will have an idea of what to expect from your chosen projectile.
Since airguns are meant to be enjoyable when you can hit your target, it just makes sense to make use of all the tools available to you for determing how your gun and the pellet will behave. That, and practice, will turn you into a better marksman, able to call your shots in competition, or place your shots effectively on game or pests.
So go to Airgun Depot's ammo selection, select the projectile of your choice, and anticipate the fun of figuring out where each shot will land now that you have a better understanding of ballistic coefficient. Or.....just go out and shoot your gun a lot to figure it out!
