A commonly asked question by both new players and more experienced ones alike is often which power source is best for airsoft. Or at a minimum which is better for a given weapon type. This article aims to answer which is better for airsoft, green gas vs. CO2! Today we are going to concentrate on two of the most common gas options used in airsoft and how they relate to certain uses, regions, systems, and climates.

This topic can be a very hotly discussed one with passionate fans in both camps but in reality, it really depends on what YOU need it to do. So let's get started with Green gas vs CO2


green gas vs. CO2

Method of charging

Firstly, aside from both being a propellant gas used in airsoft they are very very different in terms of properties and practical use. So which is the better gas for airsoft when it comes to CO2 Vs Green gas?

The first point we will look at in regards to green gas Vs CO2 is the method of getting that gas into your airsoft gun. 

With Green Gas, this is generally very easy as it comes in a large can that you basically inject directly into your gas magazines or in some cases bolt.

CO2 on the other hand is usually delivered into the system by way of a special magazine that has a space in it to accept 12gram bulbs which are pierced once installed. Some systems can take injected CO2 which uses an adapter that holds and pierces the bulb to inject it into the magazine.

The main thing to consider on that point is one of convenience. Green gas can easily be topped up whenever the user likes, such as between games when you know you have fired half a magazine for example. CO2, on the other hand, cannot be topped up and once the bulb is pierced it cannot be removed until empty (or risk freezing the magazine and your hand as it releases all its gas).

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Operating Pressures

The next point we are going to address is operating pressure. CO2 is usually higher pressure at a given temperature than green gas which is essentially Propane gas. This has a couple of important effects for us. Firstly CO2 operated airsoft guns will usually have higher muzzle energy than green gas although this is not always the case! Secondly, CO2 can usually handle working at lower temperatures than Green gas.

Some brands such as KJW do build in restrictors to the CO2 magazines of their pistols so that you see very little increase in muzzle energy when changing from a green gas magazine to a CO2 one in the same pistol.

Usually, gas guns do cycle a little quicker and sometimes with more felt recoil on CO2 than they would on green gas, especially in colder climates.

Also, the power drops off with CO2 over the course of the magazine is usually more gradual, especially in rapid-fire!

Storage and Maintenance

The third thing to consider when deciding between green gas and CO2 is storage. 

Green gas magazines like to be stored “wet” which means you should leave a small amount of gas in the magazines at all times but especially when storing them. This is to ensure the o-rings do not dry out and shrink would cause the magazines to leak the next time you fill them up.

CO2 magazines should be stored “dry” which means they should be stored without the CO2 bulb in them as CO2 will perish and compromise rubber o-rings over time.

It is worth noting that neither magazine should ever be emptied by pressing the gas relief valve as this can damage the outlet valve!


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The next point is availability. Some models are only available with one or other of these power sources available. Where this is the case the product is usually optimized for that power source and therefore should be used only with that power source for best results.

Brands such as KJW, WE, VFC, and GHK usually offer both CO2 and green gas magazines for their most popular systems, however brands such as KWC and RWA often only offer some products as CO2 powered.

Some brands, especially the Japanese brands such as Tokyo Marui and KSC are not designed to take higher pressure gas due to Japanese law and therefore you should avoid using CO2 in those brands!


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Another big factor when considering CO2 Vs Green gas is cost. CO2 compatible guns are usually similarly priced to their green gas counterparts. However, the magazines often are a little more expensive. Generally, you can expect to pay 5-7 USD more per pistol magazine over the green gas version and 10-15 USD more per rifle magazine. 

Also, the cost of running CO2 bulbs is generally quite a bit higher than if you were running green gas. However, this depends on how much both green gas and CO2 costs you locally as some regions will find one is far cheaper than the other depending upon the local market.

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The arguments in favor of green gas, meanwhile, include the fact that green gas is much cheaper than Co2 as well as the fact that it is easier to "top off" a green gas gun since you can add more gas to the gun from a green gas canister anytime you like as opposed to being forced to swap in a new Co2 bulb. 

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Green Gas Airsoft Rifle

Of course, there are cons to each propellant as well. The biggest drawback of Co2 is that it is more expensive than green gas. Another drawback to Co2 is that once the bulb is pierced, you have to wait until the bulb is completely empty or decide to waste the remaining Co2 in the bulb before you can top off your gun; there's no way to swap in a new Co2 bulb and still preserve whatever Co2 might be remaining in the bulb that you are removing. Co2 bulbs also cannot be stored inside the gun for long durations and need to be removed beforehand, once again forcing you to waste Co2 in many instances. 

Some of the drawbacks of green gas, meanwhile, include the fact that green gas canisters are much larger and more cumbersome to carry around than Co2 bulbs. The fact that green gas produces less muzzle velocity and cools down faster (and thus needs to be refilled more often) than Co2 guns are some other cons of green gas guns.

Pros and Cons of Green Gas vs Co2

Co2 Pros

  • Good Cold Weather Performance
  • More Felt Recoil
  • Less Cool-Down
  • More Consistent Power Curve Across Magazines
  • Smaller, More Portable Bulbs

Co2 Cons

  • More Expensive Than Green Gas
  • Somewhat Corrosive to a Guns's Rubber Components
  • Inability to Top Off the Gun

Green Gas Pros

  • The Ability to Easily Top-Off Gun
  • Cheaper and More Widely Available
  • The Ability to Store Green Gas Inside the Gun Between Uses

Green Gas Cons

  • Larger, More Cumbersome
  • Lower muzzle Velocities
  • Poorer Cold Weather Performance
  • Cools Down Faster


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Can I Use Green Gas in a Co2 Gun?

There are a few airsoft guns that offer the ability to use both green gas and Co2 magazines. Unless your gun is designed to use both, however, a green gas gun will not function correctly with Co2. Likewise, most Co2 guns will not function correctly with green gas. 

Is Green Gas Dangerous?

"Is green gas safe?" is a common question we get here at RedWolf Airsoft. Under normal conditions, green gas is completely safe. It is non-toxic unless an extremely large amount is inhaled. The only danger involved with green gas is the fact that it is quite flammable. As long as you keep it away from open flames, there is no risk of green gas combusting on its own.

Are There Other Kinds of Airsoft Propellants?

Aside from green gas and Co2, other popular airsoft propellants include HFC134a and high-pressure air (HPA). HFC134a is a weaker form of green gas that is only able to power plastic airsoft guns that require less pressure to operate. However, it is a gas called Freon which is illegal in most countries due to being a CFC and therefore harmful to the-Ozone. There is the aforementioned 144a replacement in Europe which is not a CFC. HPA airsoft guns, meanwhile, operate using compressed air as the propellant much like most modern paintball guns. HPA guns can be filled at home using an air compressor if you have the right attachment, but they can also be filled at airsoft shops as well as scuba shops.