How to Lower FPS on an Airsoft Gun

Stepping up to the chrono station and seeing your Airsoft gun shoot over the FPS limit is a fast way to miss the next game. Every Airsoft field sets velocity limits to keep matches safe, especially during close-range CQB play.

FPS (feet per second) measures how fast your Airsoft BB leaves the barrel, and even small setup changes can affect your readings. Gas type, spring strength, air seal, and BB weight all play a role, depending on your platform.

Here's how to safely lower FPS on AEGs (Automatic Electric Guns), gas blowback replicas, HPA systems, and spring sniper rifles.

Why You Might Need to Lower Your FPS

Every Airsoft field sets limits on the FPS of your Airsoft gun to reduce the risk of injury and keep matches fair. If your gun FPS reads too high at chrono, you're sitting out until adjustments are made.

Common FPS limits by field type:

• CQB arenas - 300 to 350 FPS
• Outdoor fields - 350 to 400 FPS
• Sniper rifles - 450 to 500 FPS with minimum engagement distances

Many fields now measure energy in joules (a unit of kinetic energy) rather than raw velocity, so swapping to heavier BBs won't fool the chrono.

Beyond compliance, reducing FPS also decreases mechanical stress on internals, improving reliability and longevity.

Lowering FPS can also improve control and consistency, which is why many newer players researching how accurate Airsoft guns are often start by tuning FPS for their local field and engagement distances.

Pictured: EMG x Daniel Defense DD5 Airsoft AEG Rifle - CYMA w/ Platinum Gearbox & Kestrel V2 MOSFET

How to Lower FPS on an AEG

AEGs (Automatic Electric Guns) are the most common platform players modify when they need to reduce the FPS quickly.

Best Method: Change the Spring

The easiest way to lower the FPS of AEGs is to change the spring inside the gearbox. A weaker spring lowers the amount of force pushing the BB forward.

Airsoft springs are rated by their theoretical muzzle velocity using a 0.20g BB, so an M110 spring is tuned for roughly 110 meters per second, an M120 for 120, and so on. These ratings mean that dropping from an M120 to an M110 typically reduces output by 10 to 20 FPS.

Many modern AEG Airsoft replicas feature quick-change spring systems, making it easy to adjust FPS through the buffer tube without fully opening the gearbox. If your gun uses a standard gearbox, a tech can usually handle the swap pretty quickly.

Other AEG Methods

When a spring swap isn't practical, consider these alternatives:

• Shorter inner barrel - A shorter inner Airsoft barrel slightly lowers acceleration time and can reduce the FPS without major internal work.
• Cut the spring - Remove one or two coils, test after each cut, and sand the end flat. This is permanent and easy to overdo.
• Minor air leak - Slightly decreasing the air seal between the gearbox and hop-up can temporarily lower FPS, though consistency usually suffers.
• Short-stroke the piston - This advanced modification reduces piston travel, helping decrease your FPS while also improving cycle speed.

Pictured: EMG x Black Rain Ordnance BRO 9mm Gas Blowback Airsoft Rifle

How to Lower FPS on a Gas Gun (GBB Pistols and Rifles)

Gas blowback rifles and gas blowback pistols operate differently. Gas pressure drives velocity rather than a spring.

Switch to a Lower-Pressure Gas

Moving from CO2 to green gas, or from green gas to duster gas, can lower FPS by roughly 30.

The trade-off is a softer recoil and slightly reduced responsiveness.

Temperature also matters. A replica that shoots fine during a cool morning game may suddenly have higher FPS due to the afternoon heat increasing gas pressure.

Adjustable Nozzle / NPAS

An NPAS (Negative Pressure Air System) helps regulate the amount of gas reaching the BB. In many systems, adjusting FPS is as simple as turning a nozzle inside the bolt assembly.

This lets you increase or decrease velocity depending on your field's requirements.

Aftermarket kits are available for popular platforms, and many GBBR (Gas Blowback Rifle) owners build DIY versions using existing internal parts.

CO2 Guns: Limited Options

CO2 capsules deliver fixed high-pressure output that's difficult to regulate.

You can lower the FPS slightly with recoil spring or hammer spring changes, but meaningful drops usually require switching Airsoft magazine types or moving to an HPA adapter setup using compressed air.

Pictured: G&P / Polarstar Full Metal M4 R3 HPA Powered Airsoft Rifle

How to Lower FPS on an HPA Gun

An HPA Airsoft gun is the easiest platform to tune for a specific FPS target.

To lower the FPS, simply reduce regulator pressure until your setup meets field requirements. Since HPA uses compressed air, the adjustment process is fast, repeatable, and easy to reverse.

You can also fine-tune dwell settings, which control the amount of time the solenoid stays open per shot.

This level of control is why many players prefer HPA when visiting multiple fields with different limits. It's one of the easiest ways to adjust power output without replacing internal parts.

What NOT to Do

Two common mistakes can cost you time, money, or your spot on the field.

Don't Use Heavier BBs to Cheat Chrono

Using heavier Airsoft BB weight may show a lower FPS reading, but the energy output often stays the same or even increases due to joule creep.

This happens because heavier BBs stay in the barrel longer, allowing more gas pressure to build behind them.

Most fields already account for this by testing with their own BBs or checking replicas measured in joules.

Don't Wear the Spring by Mag-Dumping

Some players try lowering FPS on Airsoft guns by repeatedly firing full auto to weaken the spring naturally.

Technically, it works eventually, but FPS isn't going to drop quickly enough to make it worthwhile. Meanwhile, you're putting unnecessary stress on gears, pistons, and compression parts.

A proper spring swap costs far less than replacing damaged internals later.

Find Springs and FPS Upgrade Parts at Evike.com

Whether you need a softer Airsoft spring for CQB, an NPAS for your GBBR, or a shorter inner barrel, Evike.com stocks springs, barrels, nozzle components, and adjustment parts across all major platforms.

Pair a properly tuned Airsoft gun with the right Airsoft gear, and you'll arrive at any field confident, compliant, and ready to play. At Evike.com, we've been the trusted source for millions of Airsoft players since 2001.

From upgrade parts to complete loadouts, we carry everything you need to get your Airsoft gun field-ready.