In short
- Green gas is the default. Propane with silicone oil added: the fuel most gas pistols and gas rifles are built around.
- CO2 is a different system. 12 g capsules at about seven times the pressure, only for guns made for CO2.
- Propane with an adaptor is green gas without the oil. Cheaper per fill, but the oiling becomes your job.
- Cold halves the push. At 0 °C propane has little more than half its pressure at 20 °C.
- Gas does not travel by post. Royal Mail takes neither cans nor capsules, and our webshop cannot ship gas to the UK.
The gases in one table
A gas airsoft gun, what many call a gas BB gun, carries its fuel in the magazine. Each shot lets a little gas escape: it fires the BB, the 6 mm plastic ball, and on most guns also throws the slide or bolt back to load the next one. That is gas blowback: GBB for a pistol, GBBR for a rifle.
Three fuels do that job, and one question decides between them: which pressure was your magazine built for?
Airsoft gas side by side
| Green gas | Propane with an adaptor | CO2 | |
|---|---|---|---|
| What it is | Propane with silicone oil, in a can | Plain propane from a camping cylinder | Carbon dioxide in a 12 g steel capsule |
| Pressure at 20 °C | About 8 bar; winter grades sit higher | About 8 bar | About 57 bar |
| Lubricant | In the gas | None: you oil the gun | None |
| On a cold day | Loses pressure fast | The same | Still has plenty |
| Best for | Almost every gas gun, most of the year | Heavy users who do their own upkeep | Guns built for it, and winter |
The magazine decides the gas, not the other way round.
Green gas and its strength grades
Green gas is what you get when you ask a shop for airsoft gas. Abbey Supply, a British maker, describes it as usually propane with a silicone lubricant. You press the can onto the valve in the base of the magazine.
British shops sell it by strength. Nuprol numbers its cans from 1.0 to 4.0; others print a pressure in psi (pounds per square inch). More pressure means a harder kick and more strain on the gun.
Four strengths, as Nuprol describes its own range
Low (1.0)
Low pressure, for warm days and light pistols with a plastic slide, the top half that moves. Also for a pistol whose manual asks for weak gas.
Standard (2.0)
The medium grade: an all-purpose gas for the whole year and for most gas blowback pistols and rifles. Start here unless your manual says otherwise.
High (3.0)
High pressure, for full-metal pistols and rifles and for cooler outdoor days. The winter can, for guns built to take it.
Ultra (4.0)
The strongest in the range, made for heavy gas rifles with a lot of metal to move. Not a pistol gas.
Propane with an adaptor
Because green gas is mostly propane, some players skip the airsoft can. An adaptor is a small fitting that screws onto a camping-type propane cylinder and gives it the filling nozzle of a green gas can.
What comes out is the fuel without the extras: no silicone oil, so the rubber seals of the magazine dry out unless you oil them yourself, and a strong smell that is added so leaks get noticed.
Propane with an adaptor in short
Why players do it
- A large cylinder gives many more fills than an airsoft can.
- It behaves like standard green gas.
- No oil ends up on the hop-up rubber, the part that puts backspin on the BB.
What it asks of you
- You oil the seals yourself, regularly, or they start to leak.
- The smell is unwelcome indoors, and not every site wants it where players reload and rest.
- One strength only: there is no winter grade.
CO2 capsules
A CO2 airsoft pistol takes no gas from a can. A 12 g steel capsule goes into the magazine or the grip, where a pin pierces it, and it feeds the gun until it is empty.
The pressure is in another league: about 57 bar at room temperature against about 8 for propane. That is why CO2 pistols kick harder and keep working in the cold, and why their magazines are built differently.
Temperature: what works in a British winter
The gas in your magazine is a liquid with a little vapour above it, and the vapour does the work. How hard it pushes depends on the temperature of that liquid, so a winter skirmish just above freezing is a different day for a gas gun than a June afternoon. Spare magazines kept in an inside pocket are the cheapest fix.
- Propane at 20 °C
- 8.4 bar
- Propane at 0 °C
- 4.7 bar
- CO2 at 20 °C
- 57.3 bar
- CO2 at 0 °C
- 34.9 bar
Source: NIST Chemistry WebBook: vapour pressure of the pure gas, absolute. Green gas blends can differ.
Green gas at freezing point has lost almost half its push, so the slide moves lazily and a fill gives fewer shots. CO2 on the coldest morning still has four times the pressure propane has on a warm one. Firing fast makes it worse for both: evaporating gas cools the magazine with every shot.
Which gas for your game day?
When and where do you play most?
Outdoors, spring to autumn
Standard green gas
A medium grade, sold as 2.0 or at around 135 psi. On a hot day a pistol with a plastic slide is happier on a low grade.
Gas and CO2 in the webshopOutdoors in winter
A winter grade, or a gun built for CO2
A high grade (3.0, or a red gas) if the maker of your gun allows it. If not, standard gas and warm magazines. A pistol made for CO2 copes best.
Gas and CO2 pistolsIndoors all year
Standard green gas, checked at the chrono
Indoors the site limit matters more than the cold. Standard gas keeps most pistols inside it; ask before you bring a CO2 pistol.
Spare magazinesGas and CO2 are delivered within the EU only. In the UK you buy them from a British shop or at your site.
Wear, power and the site chrono
Every shot of a blowback gun slams the slide or the bolt backwards, and more pressure means a harder slam. It lands on the nozzle, the plastic part that pushes each BB into the barrel, and on the front of the slide.
More pressure also means more energy at the muzzle. Sites measure it on a chrono, short for chronograph, which reads the speed of the BB. A gas gun shoots harder at 20 °C than at 5 °C, so a pistol that passed on a cold morning can be over the limit after lunch. Worth asking about when you look at used gas blowback guns too.
Three fuels, five criteria
- Green gas
- CO2
- Propane + adaptor
-
Power
- Green gas
- 3 out of 5
- CO2
- 5 out of 5
- Propane + adaptor
- 3 out of 5
CO2 is often more than an indoor site allows
-
In the cold
- Green gas
- 2 out of 5
- CO2
- 4 out of 5
- Propane + adaptor
- 2 out of 5
-
Kind to the gun
- Green gas
- 4 out of 5
- CO2
- 2 out of 5
- Propane + adaptor
- 3 out of 5
propane only if you keep up the oiling
-
Ease of use
- Green gas
- 5 out of 5
- CO2
- 4 out of 5
- Propane + adaptor
- 2 out of 5
-
Cost in use
- Green gas
- 3 out of 5
- CO2
- 2 out of 5
- Propane + adaptor
- 5 out of 5
Four things people say about airsoft gas
Myth
Green gas is just propane, so any propane does the same.
Fact
The fuel is the same, the extras are not. Camping propane carries no silicone oil: use it without oiling and the magazines start to leak.
Myth
CO2 always wrecks a pistol.
Fact
In a pistol built for CO2 it is the fuel the design expects. The damage happens when CO2 goes into guns and magazines made for green gas.
Myth
Stronger gas makes a better pistol.
Fact
It makes a pistol that kicks harder, wears faster and may fail the chrono. Accuracy comes from the barrel and the hop-up.
Myth
A magazine should be stored empty.
Fact
Seals keep their shape best with a little pressure behind them: a short burst of gas before storage, not empty and not full for months.
Looking after a gas gun
0 of 5 ticked
Maintenance products in the webshop
Silicone oil, loading tools and cleaning kit: these we can send to the UK.
In stock, ships right away
Maintenance Kit P99 DAO Metal Version Co2
In stock, ships right away
Universal Cleaning Kit
In stock, ships right away
Accu-Punch Hammer & Punches
In stock, ships right away
Gun Care Pro Silicone Spray 200mlCost per shot
You will not find a pence-per-shot figure here: we have none we can stand behind, because it changes with the can, the weather and the gun. This is what moves it.
What decides what a shot costs
-
The gun. A heavy metal slide or a rifle bolt needs more gas per shot than a light plastic slide.
-
The temperature. Cold gas gives fewer shots per fill, so a winter shot costs more than a summer one.
-
The container. A camping cylinder holds far more than an airsoft can, which is the whole case for propane. A pierced CO2 capsule cannot be saved for next month.
Reader poll
What do you run in your gas gun most of the year?
- Standard green gas
- A stronger winter grade
- Propane with an adaptor
- CO2
Storing and transporting gas
At home and on the road
-
Below 50 °C. The makers print 50 °C as the ceiling for a pressurised can. Out of the sun, and never in a parked car in summer.
-
Away from flame. Green gas and propane burn. Fill magazines in fresh air, far from sparks and cigarettes.
-
Never pierce or burn a can. Not even an empty one, and keep it out of reach of children. Once completely empty it goes with the household waste in most places; check with your council.
Frequently asked questions
What is green gas?
The standard fuel for gas airsoft guns: propane with a silicone lubricant added, sold in a can. You fill it into the magazine as a liquid and each shot uses a little.
Is green gas the same as propane?
Nearly. The fuel is propane, but green gas has silicone oil mixed in for the seals and camping propane does not. Fill from a propane cylinder and the oiling is up to you.
Green gas or CO2: which is better?
Green gas, for most players: it is gentler on the parts and stays inside indoor limits more easily. In green gas vs CO2, CO2 wins on winter performance, but only in a gun built for it.
Which gas should I use in winter?
A stronger grade of green gas, sold as 3.0 or as a red or winter gas, if the manual of your gun allows it. If not, stay on standard gas and keep the magazines warm.
Can strong gas damage my pistol?
Yes. More pressure throws the slide back harder, and a plastic slide can crack under gas that a full-metal gun shrugs off. ASG advises against its winter gas in such pistols.
Can gas be posted or shipped in the UK?
Not by you in the post: Royal Mail lists compressed gases, propane and carbon dioxide canisters included, as not allowed in the mail. Our webshop ships gas and CO2 within the EU only, so buy it from a British shop or at your site.
Sources
- Saturation properties for propane NIST Chemistry WebBook, 12 November 2026
- Saturation properties for carbon dioxide NIST Chemistry WebBook, 12 November 2026
- Airsoft Jargon Buster Abbey Supply Company, 12 November 2026
- NUPROL Airsoft Gas 1.0 to 4.0, product pages NUPROL, 12 November 2026
- Ultrair gas, product pages ActionSportGames, 12 November 2026
4 more sources
- Prohibited and restricted items, personal customers Royal Mail, 12 November 2026
- Firearms Act 1968, section 57A legislation.gov.uk, 12 November 2026
- Firearms (Northern Ireland) Order 2004, Schedule 1 legislation.gov.uk, 12 November 2026
- Batteries, gas and safety Airsoft Bazaar help centre
