Demystifying Feet Per Second (FPS) for Guns

Hey friend! I wanted to shed some light on what FPS means when it comes to guns. FPS stands for "feet per second" and measures the muzzle velocity or speed of a projectile fired from a gun barrel. Understanding FPS is crucial whether you‘re target shooting for fun or competing at the highest levels.

Let‘s start by looking at some typical FPS ranges seen across different gun types:

• Airsoft pistols: Around 300 FPS
• Airsoft rifles: 300-500+ FPS
• BB guns: Up to 600 FPS
• 9mm pistol: Roughly 1,200 FPS
• 5.56 NATO rifle: Over 3,000 FPS

Higher FPS means increased range and more impact force. According to the Washington Post, 350 FPS is around where a projectile gains enough velocity to penetrate human skin. For safety, most recreational and competitive venues enforce limits on maximum FPS allowed.

But before we get into what FPS means for power and performance, let‘s look briefly at the history of FPS as a ballistic measurement…

A Brief History of FPS

While projectile velocity has surely been studied for centuries, feet per second as a standardized measurement emerged in the 1800s. Early ballistics pioneers like Charles Marvin used pendulums and strings to derive scientific velocity measurements for musket balls.

Later, chronographs became the tool of choice for quantifying muzzle velocity. Early designs used electromechanical sensors while modern electronic chronographs are exceptionally accurate. Today, measuring a gun‘s FPS is simply a matter of firing rounds across calibrated chronograph sensors.

Calculating Feet Per Second

There are a few ways to calculate the feet per second (FPS) of a gun:

• Chronographs: The gold standard. Place electronic sensors at a set distance to directly measure projectile transit time. Divide distance by transit time to get FPS.

• Shot string analysis: Fire a string of shots over a set distance. Measure overall time for string to traverse distance. Divide total distance by total time to calculate average FPS.

• Hand calculations: Take muzzle velocity in meters/second (from gun manufacturer specs) and multiply by 3.281 to convert to feet/second.

No matter the technique, key variables are distance traveled by the projectile and the time required. More distance between sensors improves measurement accuracy.

FPS and Gun Power

One way to assess a gun‘s power and potential range is looking at its FPS. Two airsoft guns with the same FPS will exhibit similar ballistic performance in terms of velocity retained over longer distances.

For example, one gun shooting 0.20g BBs at 300 FPS will have very similar range and trajectory compared to a different airsoft gun also shooting at 300 FPS with 0.20g BBs.

While not perfectly linear, higher FPS enables flatter trajectory and extended effective range. All else being equal, choose the airsoft rifle with 500 FPS over 300 FPS if you need to hit targets further away.

Firearms follow this same principle – a 9mm pistol round leaves the barrel at around 1,200 FPS, while a .308 Winchester rifle round achieves over 2,800 FPS. The rifle round shoots flatter and retains higher speed at longer ranges thanks to its much higher starting FPS.

Estimating Range Based on FPS

As a general rule of thumb, here is how FPS translates to effective range for airguns/airsoft (firing 0.20-0.25g BBs):

• 200 FPS or less: 75-100 feet max
• 300 FPS: Around 150 feet max
• 400 FPS: 200 feet+
• 500+ FPS: 250-300+ feet

These numbers can fluctuate based on projectile weight, barrel quality, and environmental conditions. Smaller calibers like .177 may experience shorter effective distances than larger .22 at the same FPS.

For firearms, typical centerfire rifle cartridges achieve 300-400 yard effective ranges, while big magnum rifle cartridges can shoot accurately beyond 1,000 yards given sufficient FPS (2,000+ FPS).

FPS and Energy – Introducing FPE

While FPS (feet per second) measures projectile velocity, another important ballistic metric is FPE – foot-pounds of energy.

FPE conveys the muzzle energy or stopping power of a gun taking into account the mass and size of the projectile.

Heavier pellets or bullets will have higher FPE than lighter projectiles with the same FPS. FPE is calculated using the projectile weight and FPS:

FPE = (Projectile Weight in Grains x FPS^2) / 450240

Two 0.177 caliber air rifles shooting at 1,000 FPS – one with 7 grain pellets and one with 14 grain pellets. Assuming 1,000 FPS muzzle velocity:

• 7 grain pellets: (7 x 1,000^2) / 450240 = 15.5 FPE
• 14 grain pellets: (14 x 1,000^2) / 450240 = 31 FPE

Despite equal FPS, the 14 grain pellets deliver twice the muzzle energy on target!

This is why FPE presents a more complete picture of gun power and destructive potential than FPS alone. Higher FPS doesn‘t necessarily mean more energy delivered downrange.

Accuracy and Consistency Matter Too!

One myth about FPS is that higher numbers automatically equate to better performance and accuracy. This isn‘t always true.

Consistent shot-to-shot FPS produces better accuracy than wildly fluctuating FPS averages. A gun reliably hitting 500 FPS with match grade ammo will often outperform an inconsistent gun averaging 600 FPS.

All else being equal, I‘ll take the airsoft rifle delivering a string of shots within 2% FPS variance over the one jumping +/- 20 FPS shot to shot.

Likewise, factors like barrel quality, pellet/BB weight match, fit and finish also play crucial roles in accuracy regardless of FPS. Benchmarking guns by FPS alone doesn‘t tell the whole story.

High FPS Tradeoffs and Considerations

While beneficial in many respects, chasing ultra high FPS above all else does come with some tradeoffs:

• Increased recoil – More FPS increases slide/bolt cycling force. Not ideal for rapid, accurate follow up shots.
• Higher ammunition cost – Quality match pellets and BBs tuned for high FPS rigs are pricier.
• Greater wear-and-tear – The forces involved in generating 500+ FPS can shorten component lifespan if not engineered properly.
• Decreased shot count – Achieving high velocities often requires more air volume per shot, reducing shots per tank or CO2 cartridge.
• Less semi-auto functionality – Cycling velocity requirements can preclude semi-auto functionality for spring-piston airguns.

For airsofters, going above field limits like 400 FPS also means adding an adjustable muzzle device for velcoity control. Striking the right FPS balance for your needs and budget is part of the fun!

Legal Regulations Around FPS Limits

Since higher FPS corresponds to more power, many jurisdictions regulate airgun FPS via laws:

• United Kingdom: Legal limit of 12 foot-pounds of muzzle energy (FPE) for airguns. Roughly equates to 800 FPS or less for 0.177 caliber based on pellet weight.

• Canada: Airguns shooting over 500 FPS are classified as firearms subject to licensing.

• U.S.: No federal FPS limits, but some states and municipalities enforce restrictions. New Jersey limits airguns to 500 FPS.

• Australia: No specific FPS limits federally, but individual states restrict airguns over a certain power threshold.

Always consult your local laws before buying an air rifle. Certain configurations like high-FPS pre-charged pneumatic (PCP) rifles may be considered firearms in your jurisdiction.

FPS Limits in Competitive Shooting Sports

Most competitive shooting organizations prohibit extremely high FPS to maintain safety and fairness:

• IPSC (handgun): Major scoring threshold – 125 power factor (bullet weight x velocity). Usually a max around 1,300 FPS with 9mm.

• IDPA (handgun): Limit of 165 power factor. Typically a max of about 1,100 FPS with 9mm.

• Airsoft: 400 FPS limits for assault rifle replicas. 500 FPS for dedicated sniper platforms.

• Field Target (air rifle): 16 foot-pound (FPE) limit for the hunter class. Approx 930 FPS with 0.22 cal pellets.

These limits aim to prevent excessive power on the range and keep competition focused on marksmanship skills.

Parting Shots

There you have it amigo – the low down on feet per second (FPS) when it comes to all things guns! Understanding your equipment‘s FPS will clue you in on critical performance factors like power, range, and accuracy potential. While not the end all spec, tracking FPS with a chronograph provides quantified data to tune your gear and your skills for success.

As with most things ballistics, don‘t put blind faith in any single metric like FPS alone. All the specs together – FPS, FPE, projectile energy, consistency, fit and finish – determine on-target results. Happy shooting!