Velocity 101: The Science of Speed

ve·loc·i·ty /vəˈläsədē/ (noun): the speed of something in a given direction, for example: "the velocities of emitted particles." In general, velocity means speed, and that’s something we know a thing or two about here at Crosman!

In this article, we will dissect the science behind airgun trajectory and performance and reveal what puts the “power” in air-powered awesomeness. Let’s start with the basics, like the difference between velocity and energy and how it correlates to the accuracy of your shot.

 

21_10_22_CRS_CrosmanChallenge_00004Muzzle Energy:

When it comes to airgunning, we like to talk about “muzzle energy,” which is the kinetic energy of a projectile as it's expelled from the muzzle of an airgun. This type of energy, measured in Foot-Pounds of Energy or FPE, is an accurate representation of the power of an air gun.

A foot-pound is a unit of measurement of energy (FPE). One foot-pound (1 ft-lb) is defined as the amount of energy expended, or work done while applying the force of one pound-force (1 lb) to move an object for a distance of one foot (1 ft).

FPE correlates to the “kill power” of your shot. In layman’s terms, the higher the FPE, the bigger the animal you can take down. The bigger the ammo and the faster the ammo, the more FPE you’ll achieve. An easy way of determining or converting the energy output of your airgun is by using an online airgun calculator tool, which can easily be found via Google. FPE is definitely something to take into consideration when selecting the right airgun for you.

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Muzzle Velocity:

At Crosman, we list muzzle velocity in Feet Per Second or FPS, which is the primary way of measuring the speed of the projectile shot from your airgun. FPS is measured by how many feet your projectile will travel through the air each second. Typically an airgun shoots a steel BB around 400 fps and your typical break barrel will shoot a 7.9 grain pellet over 1000 fps.

But what does this mean with regards to performance? As soon as a pellet or BB leaves the muzzle, the force of gravity starts to work on pulling it downward, which results in that projectile following a curved path known as the “trajectory.” The point at which the projectile meets the line of sight is the distance at which a rifle’s scope is “sighted in.” In most cases, the trajectory crosses the line of sight as the pellet rises and then crosses it again as the pellet continues on its downward path.  

Essentially, higher velocities mean a flatter trajectory. Also when it comes to FPE it's a direct correlation to the grain weight of the projectile. The faster you can shoot a particular pellet the higher the FPE. For example, if you take a standard 7.9gr pellet shooting the average 1000fps out of a break barrel it will give you 17.52 FPE. If you shoot the same pellet out of a PCP and get 1100fps it will give you 21.2 FPE.

You can achieve higher FPE if the velocity remains constant but you are able to shoot a heavier pellet. For example, if you take a standard 7.9gr pellet shooting the avg 1000fps it will give you 17.52 FPE. If you shoot a heavier 10.5gr pellet at the same speed of 1000fps it will give you 23.3 FPE.

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Energy in is Energy Out:

Simply put, more air pressure in equals more power out. How much air pressure you can reliably get, depends on the type of airgun you’re using. Here we’ll break down the different styles of airguns and their energy output to help make it easier for you to choose.

  • Pre-Charged Pneumatics (PCP) use external elements like pumps, compressors, etc. to power up. That said, they get a ton of energy out.

  • Break Barrels are harder to cock, but you’ll get more power output.

  • Variable Pumps can be pumped up to different levels of pressure, so you get “tuneable” power output.

  • CO2 airguns are easy to use, but have a lower power output.

  • Spring-powered airguns are the easiest to use, but deliver the lowest power output.

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Alloy vs Lead Pellets:

Lastly, we can’t talk about airgun velocity without discussing the different BB or pellet options and how they correlate to the speed and power of your shot.

al·loy (noun) /ˈaˌloi/: a metal made by combining two or more metallic elements, especially to give greater strength or resistance to corrosion.

Alloy pellets are faster because they are comprised of lighter matter. They offer flatter shooting (a less curved trajectory) and, up close at shorter ranges have higher kinetic energy. Overall, alloys give you higher speeds but sacrifice accuracy when you start to break the sound barrier.

lead (Pb): a soft, silvery white or grayish metal in Group 14 (IVa) of the periodic table. Lead is very malleable, ductile, and dense and is a poor conductor of electricity.

Lead pellets, on the other hand, give greater penetration as their heavier weight means they have more momentum. For most types of shooting, lead pellets are better for accuracy and penetration, even if you sacrifice some speed.

You can learn more about the various pellet options and their use vs. speed by checking out Crosman’s Ammo collection here.

This should be a basic introduction on how to choose which airgun/pellet is right for you given FPS and FPE of your beloved airgun or rifle. Have more burning questions about the topic? Check out the FAQ Page on the Crosman website for some more detailed information. There are also tons more great articles that touch on this topic on the blog, browse all past articles here. Still have questions, we’re always here to help! Contact us anytime here.

Harness the power of air with Crosman.

 

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