How to Lower FPS Airsoft

The question of “how to lower fps airsoft” comes up often in online forums. While it is well known that high FPS are generally the most powerful airsoft guns, there is a school of thought that says they are more dangerous as well. Here, we explain how to lower fps on airsoft guns so that you can have a safer, more enjoyable airsoft experience.

So, how to lower FPS airsoft? You can lower your velocity of pellets, measured in FPS (feet per second), using several methods. Because some methods can potentially damage your weapon, only two are really recommended:

• The first is to replace the spring in the gearbox with softer springs, either M100 or M90.
• The second is to “grind” the spring by firing the airsoft gun in full auto for a few hundred shots to weaken the current spring.

We recommend hiring a professional to complete this work, rather than DIY, if you are worried about damaging your weapon.

These are the simple answers, but they don’t get in-depth enough. Read on to learn the details of reducing FPS on airsoft guns!

How to Lower FPS on Your Airsoft Gun

Whether for recreation or competition, the power of airsoft guns are measured in the velocity of the pellet (BB) as it is fired from the gun. Specifically, it is measured in FPS (feet per second). Local airsoft fields and competitions use a special machine called a chronograph to measure FPS. The higher the FPS, the faster and farther a BB will travel. 

The reason an airsoft player might need to reduce FPS is because airsoft fields and competitions typically have rules and regulations which limit FPS for player safety and to create a fair playing environment.  After all, airsoft is about honing your skills and having fun, not injuring or causing other players pain. Lowering your FPS will lower your range. You will not be able to shoot as far with a lower FPS, but that might be the point!

Note: All of the following methods are DIY. If you are at all worried about damaging your weapon, or if you do not know how to disassemble and reassemble your weapon, you should consider hiring an expert to do so for you. Further, ask them to teach you so that you can help yourself in the future!

Method 1, 2, and 3: Spring manipulation

Method 1: Spring grinding

This is the easiest DIY method. Fire in auto for a few hundred shots. This is called grinding; this will make the spring weaker through use. It is easy, but it can also increase stress on other airsoft gun parts. 

Method 2: Spring replacement. 

Replace the current, overpowered spring with a low tension, softer spring. For example, M110 to M110 or M90 to get closer to 350FPS. Here are the steps to replace a string. 

• Open gun using basic tools like allen keys and phillip head screwdrivers. 
• Take out gearbox
• Open gearbox
• Swap or cut the spring
• Make sure you properly assemble the gearbox

Method 3: Cut the spring 

This is not recommended, but it can reduce FPS. If you cut the spring too short, you may accidentally render the airsoft gun unusable. If you choose this method, only cut by half a coil rotation and then reassemble and check your FPS. If it is still too high, open the gun again and repeat until the FPS is to your liking or to regulation. Use the same instructions as above for removing and manipulating the spring. 

Methods: 4 and 5: Use Different BBs

These methods will have you using different BBs than the standard. Know that some competitions and fields require a standard BB for chronograph testing and for use on the airsoft course. Therefore, substituting BBs based on size or weight may not help you depending on the rules and regulations being used. Also, make sure you are not using low quality BBs which could break and damage or cause issues in your weapon. 

Method 4: Use smaller BBs

Instead of using BBs of standard size, you could purchase BBs that are smaller. Smaller BBs will allow more air to flow around them when fired. This air becomes wasted and may reduce FPS, but it is not the best or most reliable method.

Method 5: Use heavier BBs

Instead of using BBs of a standard weight, you could purchase BBs that are heavier. When using heavier BBs, they will not travel as quickly because they require more energy to be propelled through the barrel. This could be considered cheating if you are bringing an overpowered gun into competition.