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Pellet Speed and Accuracy – Don’t be fooled!
By: Matthew Dubber – Air Arms Hunting South Africa
“The faster your gun can shoot, the more accurate it will be”. It has to be true, right? That’s what many of the major airgun manufacturers are telling everyone, but the answer is a little more complicated then that. Sure, a higher velocity will result in a flatter trajectory, but there are more factors at play than one may think. Let’s take a closer look at these factors, shall we?
To answer the question of Pellet Speed vs Accuracy, we need to first understand why a pellet was designed the way it was. Have you ever wondered why a pellet has such an odd shape compared to a bullet? The answer is quite simple: Bullets are designed for supersonic flight, and pellets are designed for subsonic flight. Because pellets are traveling at low speeds, they need be stabilized by drag, and the skirt of the pellet does just that – It keeps the center of gravity near the front of the projectile, and keeps the nose pointing forward. However, this high-drag design causes problems at speeds approaching Mach 1.
A pellet traveling at really high speeds will begin to tumble because of the forces that are exerted on the pellet as it nears the transonic zone (roughly between 900 and 1300 fps or between Mach 0.8 and Mach 1.2). A pellet traveling 900 FPS will begin to experience the problems caused by supersonic flight, because the high-drag design speeds up the air passing over certain parts of the pellet. This means that in order to achieve stable flight, a pellet needs to be traveling at 900fps or lower (theoretically). Some pellets can retain their stability at higher speeds, but I have seen very few that can stay accurate after being fired at more than 1000 FPS.
In the UK, airgunners are limited to 12 ft.lbs muzzle energy. This can actually be a blessing in disguise, as it ensures that the shooters aren’t sucked into the belief that cranking the power up is always a benefit. In South Africa, this is a huge problem. Many of the big airgun manufacturers are using velocities to market their airguns instead of muzzle energy, and as a result everybody wants that 1200 or 1400 FPS airgun. I’m sure the USA is experiencing a similar problem.
To achieve the best possible accuracy in your rifle, you will want to find the point at which you begin to lose pellet stability and then track back a bit, so that the pellet is flying fast enough to maintain a fairly flat trajectory while still maintaining its stability. If you own a gun that’s shooting really hot (950 FPS or higher), send it in to be tuned down a bit – You’ll lose some of that knock-down power, but the accuracy you’ll get will make up for that.
Is it the end of the world if you’ve bought a rifle that’s shooting too fast and you can’t do anything about it? Well, that depends on what you intend to use it for. If you’re just plinking in your backyard, then certainly not. If you’re shooting at longer ranges, however, it is absolutely vital that the pellet can maintain a stable flight if you intend to hit anything!
When the time comes to choose a rifle, don’t be fooled – Faster isn’t always better, and a lack of power may actually be a blessing in disguise. High Power means nothing if you can’t hit what you’re aiming for…but find an accurate rifle that can hit a pea at 50 Meters, and suddenly you’ll find that the power you thought you needed may not have been so important after all!