There are lots of ways to upgrade your airsoft gun to improve its performance, but this guide is about one of them: how to increase your airsoft gun's FPS.

What about downright power and speed? While there are limits to how powerful your airsoft gun can be (as designated by the organizers of airsoft events), what if you have a mid-range AEG or spring-powered, bolt-action sniper rifle and you want to tune the FPS rating to your field's limit?

Here are some of the things you can do.

Key Insights: How to Increase Airsoft FPS

• Check your field's FPS limit before you buy anything, since going over it gets your gun benched until it passes a chronograph test.
• The spring sets your FPS most directly, and the motor, gears, and battery have to be able to pull whatever spring you install.
• Air leaks, worn O-rings, and a cylinder that doesn't match your barrel waste power before it reaches the BB.
• A tight-bore barrel gives a slight boost, and a flat hop-up bucking steadies the BB's flight and cuts velocity loss downrange.
• Chrono your gun after every change so you know your real FPS.

In this airsoft FPS guide:

• Before You Upgrade Your Airsoft Gun's FPS
• Airsoft FPS Upgrades at a Glance
• Adjusting and Upgrading Airsoft Springs
• Change the Airsoft Inner Barrel
• Match the Airsoft Cylinder to Your Inner Barrel
• Create a Better Airsoft Air Seal
• Upgrade the Airsoft Hop-Up and Bucking
• Match Airsoft Gear Ratio to Your Spring
• Choose the Right Airsoft AEG Motor
• Why Is My Airsoft Gun's FPS Low or Dropping?
• Build Your Own Airsoft FPS Upgrade Plan
• Airsoft FPS FAQ

Before You Upgrade Your Airsoft Gun's FPS

Check your field's limit and your gun's current FPS before you buy a single part. Fields measure FPS with a chronograph, usually with a specific airsoft BB weight, so test your gun with the same weight your field uses.

Remember, all airsoft fields and organized games have regulated FPS by airsoft gun type. Increasing your FPS beyond the limits of the field will result in your airsoft gun being banned from the field, or until you can pass a chronograph test. 

Also consider, when upgrading your power source, or modifying the electronics, be sure your wiring can handle increased loads. Electronics and wiring that aren't properly fit can create increased heat and cause electrical fires, or damage to the gun. A MOSFET can also protect the trigger contacts.

Airsoft FPS Upgrades at a Glance

Prices are typical ranges from our current listings and change with stock.

Adjusting and Upgrading Airsoft Springs

Swapping the springs is one of the easiest ways to make your airsoft gun more powerful, whether you're operating an AEG, or sniper rifle, any spring-powered airsoft gun will benefit from a spring upgrade.

The stiffer the spring, the more force it exerts on the airsoft gun's internals, and the faster it can propel an airsoft BB.

Airsoft springs are rated with an M number, like M100 or M120, that roughly estimates the resulting muzzle velocity. An M120 spring typically produces somewhere around 400 FPS, depending on the rest of your build. Chrono your gun after installing a new spring to confirm the real number.

However, you can't just blindly upgrade your airsoft gun's springs. Be sure to check your owner's manual for specifics on the limits on the types and sizes of springs you can use.

Also, for some airsoft guns, you'll need to change the spring guide and piston head to make sure these are properly matched to the spring.

For electric airsoft guns, you may also need a more powerful (or more efficient) battery or motor with a more powerful spring. Again, consult the model's manufacturer recommendation in the owner's guide or consult us.

Change the Airsoft Inner Barrel

In some instances, changing the inner barrel to a tight-bore barrel may be able to give your airsoft gun a slight boost in FPS.

Many airsoft guns come with a barrel in the 6.08mm to 6.10mm range. This standard size is just good enough, but if you want to give a slight boost to muzzle velocity, opt for a tight bore 6.01mm, 6.03mm, or 6.04mm barrel.

Side note: if you have a GBB airsoft pistol and want to increase accuracy but not necessarily FPS rating, opt for a Maple Leaf Crazy Jet inner barrel, which will create a cushion of air around the BB as it leaves the barrel, which will boost short-range accuracy.

If you change barrel length, make sure your cylinder still matches it.

                                      

Match the Airsoft Cylinder to Your Inner Barrel

Cylinder porting, the holes cut into the side of the airsoft cylinder, needs to match your inner barrel length. A full, non-ported cylinder suits a longer inner barrel that needs the full compression stroke, while a ported cylinder releases some air early and suits a shorter barrel. Running a full cylinder with a short barrel wastes air and adds strain instead of adding power.

Do not upgrade to a non-ported cylinder without also upgrading to a compatible barrel. Many airsoft guns use ported cylinders because they protect the platform's internals with an extra safeguard against over-compressed air, which can damage them.

Still, with a long enough barrel, changing to a non-ported cylinder will deliver more highly compressed air before the BB passes through the barrel. The higher pressures will effectively improve the airsoft BB's FPS as it leaves the barrel.

By the way, use a metal one if you do make this upgrade. Metal parts are more durable than synthetic polymers and will last longer. They're also less likely to fail.

Create a Better Airsoft Air Seal

There are a few places to check inside the airsoft gun to make sure that you have a good seal, which will in turn affect speed at the muzzle.

First, check around the cylinder head. There are ways to check if there's a good seal, but a good practice is just to seal the cylinder head with thread tape to prevent leaks.

The cylinder head-air nozzle connection is a weak point for many models, even high-quality airsoft guns. This is something you can't easily fix with thread tape. Instead, replace the O-ring.

The hop-up housing around the barrel is another weak point on many airsoft guns, especially gas blowback airsoft guns. If the connection is weak, air will leak out between the two parts.

This problem, however, is easy to fix. Simply make a few passes around the connection with thread tape to create a more effective seal that will substantially boost FPS.

Airsoft Piston Heads and Air Nozzles

The piston head is the other place to check. It carries an O-ring that seals against the cylinder wall on every compression stroke, and a worn piston head O-ring is a common cause of FPS that slowly drops on an older build.

The air nozzle matters too. It moves with the tappet plate and presses against the hop-up bucking to seal the chamber, which sends compressed air through the BB. Many upgraded nozzles add an internal O-ring that stops air leaking past the nozzle itself.

Nozzle length is sensitive, since a difference of even a tenth of a millimeter can cause feeding jams or double-feeding. Measure your stock nozzle with digital calipers before ordering a replacement.

Upgrade the Airsoft Hop-Up and Bucking

Increasing the hop-up might not directly increase your FPS, but it can stabilize the flight of the airsoft BB and can potentially diminish the loss of airsoft BB power downrange.

Specifically, opt for a flat hop-up bucking that has a greater contact surface area with the BB and can substantially decrease wobble. Diminishing wobble and creating a more consistent backspin will stabilize the BB flight, resulting in less loss of velocity and greater accuracy.

A new bucking can also bring FPS back up if the old one was leaking air around the BB. If you'd rather replace the whole assembly, hop-up units are sold separately.

Match Airsoft Gear Ratio to Your Spring

The gear set converts your motor's spinning into the pull that cocks the piston against the spring on every shot. A standard AEG gearbox runs three gears in sequence: the bevel gear connected to the motor, the spur gear in the middle, and the sector gear that engages the piston.

Gear ratio, written as 12:1, 16:1, or 18:1, is how many times the motor spins per full gear cycle. A lower ratio, closer to 12:1, favors rate of fire. A higher ratio, 18:1 and up, turns slower with more mechanical advantage, which suits a heavy spring on a high-FPS or DMR build.

Gear sets are sized to a gearbox version, commonly V2 or V3, so confirm yours before ordering. Hardened or stainless sets resist stripped teeth better under heavy use.

                                                                 

Choose the Right Airsoft AEG Motor

One more thing to look at on an electrically powered airsoft gun is whether to upgrade the motor.

First thing, upgrade to a motor with rare earth magnets or neodymium magnets if your stock motor is made with ferrite magnets. Neodymium magnets are stronger and longer lasting.

Second, if your motor is a high-speed motor and you're running a heavier spring, switch to a high-torque motor. This might not sound like it makes sense, but high-speed motors deliver higher RPM, which enables them to deliver a higher rate of fire. They don't improve the power of the airsoft gun.

A high-torque motor (22 TPA or higher, TPA being turns per armature) pulls a heavier spring reliably, and the spring is what sets FPS. A high-speed motor (14 TPA or lower) gives you a higher rate of fire, but paired with a heavy spring and a high-torque gear set it can bog down and strain your battery.

Why Is My Airsoft Gun's FPS Low or Dropping?

If your airsoft gun's FPS has dropped, or you can't hit the number you expected after an upgrade, an air leak is a common cause. The same few spots tend to be responsible:

• A worn piston head O-ring or cylinder head seal, which lets compressed air leak instead of fully reaching the BB
• The cylinder head to air nozzle connection, where the fix is a new O-ring
• A weak connection at the hop-up housing, especially on gas blowback guns, where thread tape helps
• A cylinder whose porting doesn't match your inner barrel length
• A spring heavier than your motor and battery can comfortably pull

Chrono the gun after each fix so you know which one made the difference.

Build Your Own Airsoft FPS Upgrade Plan

There's no single FPS upgrade plan that works for everyone. Before you buy parts, run through these questions:

• What is your field's FPS limit, and what is your gun shooting now?
• Is it an AEG or a spring-powered gun?
• Can the rest of the gearbox handle a stronger spring, including the motor, gears, battery, and wiring?
• Is this gun worth upgrading, or would a new one make more sense?

Airsoft FPS FAQ

Will a Stronger Spring Damage My Airsoft Gun?

It can add stress. A stiffer spring puts more load on the gears and gearbox, and a linear spring, with evenly spaced coils, stresses them more than a progressive one at the same power rating. Match the motor, gears, battery, and wiring to the spring you choose.

How Do I Lower My Airsoft Gun's FPS?

Drop to a lower M-rating spring, or fine-tune within a narrower range with spacers or carefully clipped coils. Chrono the gun after any change.

Does BB Weight Change My Airsoft FPS?

Yes. At the same power, a heavier BB leaves the barrel slower than a lighter one, which is why fields state their limits with a specific BB weight. Test your gun with the weight your field uses.

Do I Need to Open My Airsoft Gearbox to Change the Spring?

Yes, unless you're running a quick-change spring system built to avoid it.

Questions? Call Us!

Interested in making some of these upgrades to boost your airsoft gun’s FPS but not sure where to start? Get in touch with us at 800-581-6620 and we’ll help you figure out where to start.

We also sell a lot of different types of airsoft guns including beginner airsoft guns and cheap airsoft guns that are perfect blank slates for upgrades and customizations.

We also sell rechargeable batteries, green gas, and CO2 for gas-powered airsoft guns, airsoft ammo, and parts, too - everything you need to upgrade your favorite platform whether it’s a Tokyo Marui GBB airsoft pistol or a G&G Raider AEG. 

If you have any questions about how to make any of these upgrades, get in touch with us via the number above.