How to lower FPS on an Airsoft Gun

Lowering your gun FPS isn’t rocket science. In this blog post, we will provide you with the basics of how you can achieve lower fps on your replica.

Why lower FPS on an airsoft gun?

You might want to lower the FPS of your airsoft gun for several reasons:

  • To comply with the rules of various airsoft fields and events.
  • To decrease the stress on internal parts of airsoft guns.
  • To get your gun in a different rule category. For instance, if you want to play a game that allows for full auto under 1 Joule, etc.

The options you have differ if you need lower FPS on electric or gas airsoft replicas. Let’s dive right in.

Lowering FPS on AEGs

Spring exchange

The most obvious and effective method to change FPS. If your replica has a quick spring exchange feature, it’s pretty straightforward. If not, you will have to open up your gearbox, change the spring and assemble it again, which can prove quite challenging if you’ve never done it before.

Cutting the spring

If you have no weaker spring at hand, you can remove a few twists from the spring coil, which will dial down FPS. Do this procedure slowly and regularly check the power after every cut so you don’t end up with too weak of a gun. After finding the correct spring length, flatten the cut-off part of the coil with sandpaper or a file till it’s flat. But be careful. This “upgrade” will be permanent, and you may destroy your spring.

Here is a video of StayFreshShoe explaining cutting sniper rifle spring

Creating Air Leakage

Intentionally creating a minor air leak in an airsoft gun is somewhat unconventional yet effective in reducing its FPS. This technique typically involves altering the seal between the gearbox and the hop-up unit or within the piston head in AEGs.

By slightly loosening these seals, the airsoft gun is made to intentionally bleed off a small amount of air during each shot. This air leakage means less air is available to propel the BB out of the barrel, resulting in lower FPS. It’s a method often used as a quick fix or a temporary solution when other methods of reducing FPS aren’t available.

However, it’s crucial to approach this method with caution as it can impact the consistency and reliability of the gun’s performance.

Shortening the piston travel

By removing a few teeth from the piston, you can decrease a few FPS, and the welcomed side effect rate of fire will increase. Nonetheless, this procedure should be done by skilled tech since it’s quite complicated, and you can break your replica pretty quickly. Here is an animation to help you understand.

Shortening the Inner Barrel

Shortening the inner barrel of an airsoft gun is a practical method to decrease its FPS. This technique works because a shorter barrel reduces the distance over which the air can propel the BB, thereby decreasing its exit velocity. Essentially, the BB has less time to accelerate, resulting in a lower FPS.

This method quickly adapts your guns to comply with specific field FPS limits or for those seeking a more CQB-friendly setup. It’s a straightforward physical modification that, when done correctly, can effectively bring down the FPS without drastically altering other aspects of the gun’s performance. However, it’s important to note that this change might slightly affect the gun’s range and accuracy.

Lowering FPS on spring-powered sniper rifles

For sniper rifles, you can use the following tips already shown with AEGs:

  • Spring exchange
  • Cutting the spring
  • Shortening the inner barrel

And also:

FPS adjustment rings

FPS adjustment rings are a convenient and effective solution for the muzzle energy in airsoft spring sniper rifles. These small rings are designed to fit around the spring guard, allowing for less travel distance of the spring.

This is a simple, non-invasive way to alter the rifle’s power, allowing for quick adjustments without disassembling the entire gun. They are ideal for players who need to frequently adjust their FPS based on different game scenarios or regulations. Moreover, these rings provide a way to maintain the rifle’s longevity, as they prevent the need for constantly replacing springs for FPS regulation.

Lowering FPS on Airsoft Gas Pistols and Rifles

Pickup a weaker gas

Gas Blowback airsoft guns typically use gases like green gas, propane, or CO2. Each gas type has its own pressure level, which directly influences the FPS of your GBB gun. Green gas and propane are generally lower in pressure compared to CO2, making them suitable choices for reducing FPS. Try looking into Green and Blue Gas if needed. Just keep in mind that if it’s too cold for a given gas, your replica may also fail to work due to the lack of power.


You can HPA tap your GBB or buy a specific HPA adapter for your replica.
How will this help? You will be more flexible and consistent with the power since your gun is connected to an adjustable regulator that limits the amount of compressed air flowing into your replica. With just a few turns of a screw, you can change your power. We went more in-depth with this topic:

Adjustable Nozzle & NPAS

An adjustable nozzle allows you to limit the amount of gas you let through to the BB. More gas = more FPS, and vice versa. Interestingly enough, if you already run a GBBR, you can make this one with the parts already in your replica, essentially for free.

Nozzle restrictor

Nozzle restrictors offer a precise and straightforward means to lower the FPS in gas blowback airsoft guns. These small components are installed in the gun’s nozzle, where they function by constricting the flow of gas each time a shot is fired. This restriction limits the amount of gas propelling the BB, effectively lowering the FPS. However, this is not something you could make at home easily.



If you need to decrease your FPS with AEGs, start by checking if you can change the spring. With snipers, you can do pretty much the same or simply get FPS rings. They cost under 10 bucks and are non-invasive. With GBBs, the easiest is to choose a different gas. A DIY NPAS is also a doable low-cost solution.

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