Understanding the Power of Airguns: FPS and Calibre Explained

By Published On: 1 February 2024Categories: Air Gun

When selecting a quality air rifle or pistol for your needs, decoding technical specifications proves essential yet often confusing. Terms like “FPS”, “ft-lbs”, and “calibres” define critical performance metrics, but remain a mystery to most beginners.

We demystify these key specifications that determine an airgun’s capabilities and help match the ideal gun for your planned uses. From target practice to pest control, understanding the power and projectile characteristics enables choosing the perfect airgun for you.

Defining FPS Velocity

The most referenced metric, FPS, denotes “Feet Per Second” or the speed at which a pellet travels when leaving the muzzle before drag slows its flight. Put simply, higher FPS equals a flatter trajectory and extended range as gravity has less time to curve the pellet’s path before it reaches the target.

So why does velocity matter in your air rifle selection? Airguns designed for competitive target shooting demand ultra-high 1,000+ FPS velocity for flatter long-range ballistics. On the other hand, a 500 FPS plinking gun presents a cheaper option for casually perforating cans at closer distances.

Calculating Muzzle Energy Foot-Pounds

While FPS defines pellet speed, “foot-pounds” energy indicates the kinetic power and impact force generated based on velocity and projectile weight as per the equation Energy = (FPS^2 x Pellet Grains)/450240.

In practical terms, the ft lbs measurement converts a rifle’s FPS performance into usable impact force on the target. This means two 500 FPS air rifles can demonstrate vastly different effective power depending on their calibrated pellet weights and resulting ft-lb energy. Heavier pellets hit harder!

This makes muzzle energy a key statistic when selecting an airgun. Hunting rifles require higher foot-pounds within your air gun licence UK possession limits to ensure clean kills. 

Understanding Calibres

The final key metric ‘calibre’ generates much confusion! Calibre refers to the pellet diameter or bore size rather than any power measurement. The most common recreational airgun calibres include .177, .22, .25 and .357 inch bores.

Despite larger size, bigger .25 or .357 pellets are NOT inherently more powerful than smaller .177 calibre if their FPS velocities are equal. Their additional weight only enables higher ft lbs energy calculation.

Instead, ideal calibre depends on your unique shooting application. Light .177 pellets offer flatter trajectories for long-range target shooting. Heavy .22 pellets provide extra mass for stability in windy conditions. Large .25 calibre pellets enable big game hunting within air gun laws.

Choosing Your Perfect Airgun

Armed with clearer understanding around industry terminology, focus specifications to your applications, be it plinking targets or pest control hunting.

Here at The Wolfman, we stock famous brands offering supreme accuracy and reliability across power levels and firing actions. And remember, we pride ourselves on top tier UK delivery and customer support, so never hesitate to contact us for guidance finding your ideal airgun!

About the Author: The Wolfman Store

After over 30 years experience in the Airgun trade, The Wolfman Store are delighted to announce our new website, enabling us to supply direct to the shooting community for the first time. Combining a vast stock of established favourites with exciting products new to the UK, The Wolfman Store will be striving to provide unparalleled service at the most competitive prices.

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