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FPS Increase & Decrease Guide

Sometimes the FPS (or here in Japan m/s (metres per second) /Joule) is too high or too low and needs fixing.

For example, if your weapon is barely reaching 30m before the BB drops, flies upwards, or maybe at a field it was chrono'd in a little too hot and you cannot use it.


Most Airsoft field limits cap out at 98 m/s to comply with the Japanese firearm laws as well as reducing the risk of injury on the field. Sadly, they will fire three shots, if just one of them goes over the field regulation, they will not allow the weapon to be used. I have been shot with a gun that was firing at 150 m/s, it broke skin and was embedded. Suffice to say, it was not a fun day when I was hit with them at full auto and had to dig 6 of them out of my thigh.


 

How to Lower power


Downgrade the Springs

There are two ways to weaken your springs.

  1. Wearing This is an easy, but time-consuming method where you simply fire the gun in full auto a few hundred times to essentially wear the spring a little and make it less rigid. However, this also will wear out the other parts of the gun and could lead to possible damage.

  2. Spring replacement If you install a softer spring, it will reduce your weapon's overall power. If you change from an M110 spring to an M90 spring, you can lower the power output by around 18 metres per second.


Shortening The Inner Barrel

Generally the length of the barrel will affect range and in the case of a BB, power. When the BB leaves the barrel, the elements such as wind, rain etc. will hinder the BB's flight. By effectively shortening the barrel slightly, you expose the BB to more external forces that will hi8nder the flight path and reduce the power and speed. But, you do need to bear in mind that the adjustments need to be precise as cutting off too much can end in misery.


Changing Cylinder types

Cylinders can be ported or non-ported. Ported cylinders are often called "vented" and non-ported cylinders are "unvented".

Vented cylinders will draw air from the rear of the piston.

Unvented cylinders will draw air from the end of the barrel.

As a result, a vented cylinder offers more air flow and can lower the power of the gun itself and the most common type of cylinder on replica guns.

 

How to Increase power


Upgrading Springs

Any Airsoft modder knows that the quickest, and easiest way to upgrade your velocity is through the main spring. As the heart and soul of your Airsoft’s gearbox, changing out the the main spring can have a big impact on your BB's velocity.

If you install a harder spring, it will be effective in increasing the velocity. But, it also means you will need to change some plastic parts to metal such as the spring guides. Ideally ones with ball bearings.


Because a harder spring exerts more pressure, which requires a stronger mechanism to hold it. If you forgo a proper bushing replacement, your plastic guide can break, dropping shards of plastic in the gearbox, creating more serious issues.

You may also need to replace or reinforce the piston heads and change the motor for a higher torque, to ensure that full compression is properly delivered and ensure that the gears go through a full cycle for each shot.


Switching From Ported To Non-Ported Cylinders


Ported cylinders are better for all-rounder Airsoft guns, and non-ported cylinders are better for boosting BB velocity. In a ported cylinder set-up, the air sealing process is faster and delivers faster speeds. But be aware that metal cylinders are much better and last longer than their plastic counterpart.


Check your Hop-Up

Sometimes people set their hop-up too high, this can cause the metres per second to suffer. Ideally reduce it down to basically nothing and chrono it to check if it makes a difference. If it doesn't, then keep troubleshooting. Another issues can be the bucking being worn. I have seen them with tears and part of it interferes inside the barrel causing a reduction in overall velocity.


Air Leaks

Check your Airsoft gun around the air nozzle, if you can fire a few shots and feel air bleeding out, then you have an air leak. Leaky air nozzles will reduce the effectiveness of the seal between the barrel of the gun and the gear box, which can significantly impact the velocity of each shot.

Air nozzles with an O-ring are better for creating a strong seal, but order the best type for your weapon model if you need a replacement. The cheap ones tend to deteriorate quickly.


Adjusting The Barrel

Another simple way to upgrade m/s on your airsoft weapon is to replace the inner barrel. Since the factory default for Airsoft guns is typically a 6.10mm barrel, you can upgrade your weapon’s m/s by replacing it with a narrower 6.03 or 6.01 mm tight bore.

Upgrading to a tight bore barrel means fitting a new hop up nub and bucking set, but capitalizes on air compression in your gun. However. This does not always offer a great advantage in improving the velocity of BB's.

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