How does HPA in airsoft work?

16th Mar 2022

How does HPA in airsoft work?

What is an HPA gun?

Airsoft has evolved to have a multitude of different designs for the weapons you use. These include the weakest which are spring powered rifle, AEGs or electric airsoft guns, gas powered guns including green gas and CO2 and finally high-pressure air airsoft guns.

As apposed to the electric, CO2 guns which all do an amazing job of concealing their internals and methods of holding energy, HPA guns have an external store of high-pressure gas, fed into the gun through a tube or attached as part of the body.

Rather than relying on a mechanical process to propel the BB these guns provide an instant burst of pressurised air every time the trigger is pulled. This gives it the ability to fire at a higher rate than even its real counterparts.


Pro of using an HPA gun

As you can imagine having such a powerful source of power gives these weapons some impressing performance ability such as:

Rate of fire –

As mentioned earlier, HPA guns provide an incredible speed to your shooting. As well as having the potential to have a higher rate of fire than any other kind of gun these can also be purchased or modified with the feature to control that output. Usually reserved for the more expensive options this means you can manually alter the rate of your fire without affecting the FPS of your gun.



The storage tank on an HPA gun is rated to hold an incredible PSI inside it which is an incredible amount of pressure resulting in an extraordinary amount of force. With the ability to control the output from the tank the FPS can also be changed. The advantage of having such a high velocity is an increase in accuracy over a greater distance.

Either using an electronic circuit board or a mechanical valve attached to the trigger mechanism means that HPA airsoft guns can control the exact amount of air that can enter the chamber when firing. This offers a degree of consistency to every shot which is taken. As appose to CO2 guns which will have fluctuating output based on the pressure in the canister.


Quieter –

When compared to a real-life gun you may not describe it as loud, but when you are playing airsoft it can be very easy to hear others using their airsoft guns. These sounds are the gears, pistons and cylinders in AEGs moving to produce the air pressure needed to fire the BB and the gas in CO2 powered weapons rushing to fill the chamber and moving the mechanism inside. As you may imagine this is not an issue for the HPA gun. Despite being one of the most powerful types of airsoft guns they produce the least noise. Due to their simple internals, the only sound which is produced is the one made by the BB exiting the barrel and even this can be dampened further using a suppressor.


Simpler internal design –

Unlike AEGs there are very few moving parts involved in the running of an HPA gun. This is because it does not need pistons, motors, removable batteries, or gears to operate. The result of their simple design means they aren’t as liable to malfunctions. Provided the engine is installed properly there is little to no chance of something going wrong.



Whilst there are alot of positives to using an HPA gun there are a few points that you need to keep in mind before switching to one for your primary carry.

Weight –

One of the negatives involved in running an HPA set up is the weight required to operate it. In addition to the already heavy airsoft gun containing the working internals as well as the usual metal frame you will need a heavy-duty line as well as an external tank rated to hold a high enough pressure. One alternative is the typical external storage with a line is a smaller tan which can be screwed directly into the gun and usually acts as a stock. This will decrease the amount of air that can be held as well as increasing the weight of the gun further but will also grant you more mobility and lightens your personal load.


Cost –

The major factor which can put people off running with an HPA gun is the price, typically a HPA gun will cost £500+ for the gun alone. This is due to the fact HPA guns are not factory made but usually require a donor gun to be destroyed before they can be made. On top of this there is the added price of the line and external storage. Altogether it can cost nearly £1000 to get started, meaning these guns are usually used by experienced airsofters.


Lack of Realism –

One of the main selling points of airsoft is the ability to get a, as close as you can, real to life experience of what it would be like to be in a gunfight without the risk. However, having to attach your gun to a backpack or attaching a gas canister to the outside of the gun can break the immersion of realism. The ability of these weapons is also unrealistic, the rate of fire in an HPA gun can be far higher than a real gun.


Safety –

One of the most important things people who host airsoft need to maintain is safety which can pose an issue for anyone wanting to use an HPA gun. This is due to almost all airsoft grounds having a maximum FPS limit which any high-pressure air gun can easily break. This can result in some grounds outright banning them as they can be adjusted even once they have been checked for legality.


In conclusion, HPA guns are a very specialised piece of equipment which lend themselves to the more experienced airsofter. Before you get one you should do your research to get the best deal as well as to make sure that your local ground allows them.


Why not read our previous blog on the 10 best gifts you can buy for an airsofter?

Abbey Supply's airsoft Christmas list

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