It is a cold Saturday morning at your local Kent site. You draw your gas pistol, squeeze the trigger, and instead of a crisp crack you get a limp puff and a slide that barely moves. The gas has not run out. It has gone cold, the seals have not seen oil in months, and now you are sitting out the first game of the day.
Almost every problem like this is preventable. Gas guns are some of the most satisfying kit in airsoft, with real recoil and a proper cycling action, but they ask for a little care in return. Look after the propellant and the seals, and a Gas Blowback (GBB) pistol will run reliably for years. Here you will learn how to store green gas and CO2 safely, keep the seals healthy with silicone oil, avoid over-filling, and get the best from a gas gun through a British winter.
We have been servicing and resealing gas guns at our Rochester workshop on the Medway City Estate since 2006. In that time hundreds of leaking magazines have crossed the bench, and the same handful of habits fix nearly all of them.
In this guide:
- Green gas and CO2: two fuels, two temperaments
- Storing green gas and CO2 safely at home
- Seal care and silicone oil
- Running gas guns through a British winter
- Travel, posting and the law
- Common gas gun faults and fixes
- When to bring it in for servicing
Green gas and CO2: two fuels, two temperaments
Before you think about storage, it helps to know what you are actually handling. The two common propellants behave very differently, and that difference shapes every care decision that follows. We cover the buying side in our green gas vs CO2 comparison, but the care side matters just as much.
Green gas is a propane-based propellant supplied in a refillable bottle. It runs at a relatively modest pressure at room temperature. Crucially, it comes with silicone oil already blended in. Every time you charge a magazine, a little lubricant travels in with the gas and coats the seals as the gun cycles.
That built-in lubrication is why green gas is so forgiving. It is the propellant most players start with, and the one that punishes neglect the least.
CO2 is a dry gas supplied in sealed 12g capsules, and it runs at a far higher pressure than green gas. That extra pressure gives snappier recoil and stronger performance in the cold. It also carries no lubricant of its own, so it dries out seals faster and puts more stress on internal parts. In short, a CO2 gun asks for more attention than a green gas one.
| Factor | Green gas | CO2 |
|---|---|---|
| Pressure and recoil feel | Softer, smoother | Sharper, snappier |
| Cold-weather performance | Drops off noticeably | Holds up better |
| Built-in lubrication | Yes, silicone blended in | None, a dry gas |
| Seal wear | Gentler on O-rings | Harder on O-rings |
| Supplied as | Refillable bottle | Sealed 12g capsules |
| Best suited to | Everyday play, beginners | Winter games, higher power |
If you are still weighing up which platform suits your play, our overview of AEG, GBB and HPA gun types puts gas guns in context alongside the alternatives. It is worth a read before you commit to a propellant.
Storing green gas and CO2 safely at home
Green gas is propane-based, which means it is flammable. That single fact drives every storage rule below. Handled sensibly it is perfectly safe, but it deserves the same respect as any pressurised aerosol.
Storing green gas bottles
- Store the bottle upright. This keeps the valve seated correctly and reduces the chance of a slow leak.
- Keep it cool and shaded. Heat raises the pressure inside the bottle, so a cool, dry, dark spot is ideal.
- Ventilate the space. A garage or shed away from living areas, heaters and ignition sources beats a warm indoor cupboard.
- Never puncture or incinerate it. Keep the bottle away from open flames and do not force a nearly empty one.
Green gas is a form of liquefied petroleum gas, so the sensible-storage principles the Health and Safety Executive sets out for LPG apply in miniature. Cool, ventilated and away from ignition covers the essentials.
Marcus, a regular at one of our local sites, learned this the hard way last July. He left a nearly full green gas bottle on the parcel shelf of his car during a heatwave, then forgot about it for a fortnight. When he came back the bottle had vented most of its contents through the safety of the valve, leaving a faint propane smell and a wasted tenner. Nothing dangerous happened, but a shaded footwell would have saved the gas. Heat is the one thing green gas will not forgive.
Running low? Keep a spare in so you are never caught short on game day. Our airsoft gas and consumables range covers green gas and CO2 alongside the BBs and batteries you top up most.
Storing CO2 capsules
Capsules are simpler to store than a bottle, but they still hold a great deal of pressure. There is one habit in particular that saves both money and frustration.
- Keep unpierced capsules cool and dry. Sealed capsules are stable and last for years, so simply keep damp away to stop the steel corroding.
- Never leave a pierced capsule under load. Once pierced, a capsule should be used up and removed, or the constant pressure flattens the O-rings and causes leaks.
- Handle empties responsibly. A spent capsule holds a little residual pressure at first, so vent it fully before you recycle the steel, and never throw one on a fire.
Because both propellants are pressurised and flammable, the same broad thinking behind the HSE guidance on storing dangerous and flammable substances applies at home. You are not running a warehouse, but the logic is identical: keep quantities modest, cool and away from anything that could ignite them.
| Do | Don’t |
|---|---|
| Store bottles upright in a cool, ventilated space | Leave gas in a hot car or sunny windowsill |
| Keep capsules dry so the steel does not corrode | Store a pierced, live CO2 capsule in a magazine |
| Keep everything away from heaters and open flames | Puncture, dent or incinerate a bottle or capsule |
| Buy fresh gas locally as you need it | Hoard large amounts in a warm cupboard indoors |
| Vent empties fully before recycling | Bin a capsule that still holds residual pressure |
Seal care and silicone oil
The seals are the heart of any gas gun. Keep them lubricated and the gun stays gas-tight and cycles cleanly. Let them dry out and you get the classic symptoms: weak shots, gas escaping down the barrel, and magazines that will not hold a fill overnight.
Lubricate with pure silicone oil
Put a drop of pure silicone oil on the magazine fill valve every few top-ups. When you next charge the magazine, the incoming gas carries that oil through the system and keeps the internal O-rings supple. It is a two-second job with a real payoff.
Green gas guns need this less often, since the gas is already lubricated, but it remains good practice. CO2 guns need it more often, because the dry gas gives them nothing. Many players oil a CO2 magazine every couple of games as a matter of routine.
Only ever use 100 percent silicone oil. Petroleum-based lubricants such as WD-40 swell and destroy airsoft rubber seals. This is the single most common mistake we see on the bench, and it turns a healthy magazine into a leaking one.
Fill the magazine without over-filling
When charging a green gas magazine (never a clip), a few seconds is usually enough. Hold the bottle upright against the fill valve and stop once you hear the gas settle. Blasting gas in long after the magazine is full just wastes it and chills the seals.
If liquid gas spits back out of the valve, you have gone past full. Over-filling does not make the gun hit harder; it simply cools the O-rings and can leave the magazine venting on a warm day. Short, controlled fills are kinder to the seals and to your gas supply.
Wipe down and store charged
After a game, wipe the gun down to remove dirt, moisture and BB debris, then give the external metal a light protective coat. Store green gas magazines with a small amount of gas left inside. That residual pressure keeps the seals seated and stops the O-rings drying out between games.
Empty gas magazines mean dry seals, and dry seals mean leaks. Our general airsoft gun maintenance guide walks through the cleaning routines that apply across every platform, gas guns included.
Running gas guns through a British winter
This is where a lot of British players get caught out. Gas pressure is tied to temperature. As a magazine gets cold, the pressure inside falls, and with it your muzzle velocity and the force available to cycle the action.
Fire several fast shots and the gas expanding out of the magazine cools it further, so performance drops off mid-string. On a frosty morning a green gas pistol can feel sluggish and begin to short-stroke, where the slide fails to travel far enough to chamber the next BB.
CO2 copes noticeably better in the cold, because it starts from a much higher pressure. Even with a temperature drop there is plenty in reserve, which is exactly why many players switch to CO2 magazines for winter skirmishes.
Priya found this out at a January game near Maidstone. Her green gas pistol ran beautifully in the car park, then faded to a dribble after two magazines out on a frozen field. She had been dumping a full magazine in one long burst, which chilled the gas even faster. Once she started keeping spares in an inside pocket and firing in shorter strings, the pistol held up for the rest of the day. A warm magazine and a bit of patience did more than any upgrade could.
Whichever propellant you run, a few cold-weather habits help:
- Keep spares warm. Store magazines in an inside pocket close to your body, and rotate them so a warm one is always ready.
- Fire in shorter strings. Give the gas a moment to recover between bursts rather than emptying a magazine in one go.
- Never use direct heat. Body warmth only; a car heater vent or any flame can overheat a pressurised magazine and is genuinely dangerous.
Travel, posting and the law
Green gas and CO2 are pressurised, flammable items, so they are treated like aerosols in transit. That has real practical consequences for how you move them around.
Do not pack gas in aircraft luggage, checked or cabin. Pressurised gas cartridges and flammable propellants are restricted dangerous goods, and taking them on a flight is not worth the risk to you or anyone else on board.
Posting gas is a non-starter too. Aerosols and compressed gases sit on the Royal Mail list of prohibited and restricted items, so you cannot drop a bottle of green gas in the post. Buy your propellant locally instead, in store or delivered by an appropriate ground courier who is set up to carry it.
When you travel to a game by car, keep bottles and capsules cool, upright and out of direct sun. A shaded footwell is fine; a sun-baked parcel shelf is not. The goal is simply to stop heat driving the pressure up while the kit is out of your hands.
Common gas gun faults and fixes
Most gas gun grumbles trace back to seals, gas or temperature. Before you assume the worst, run through the quick diagnostics below. Many are a five-minute fix at the kitchen table.
| Symptom | Likely cause | Fix |
|---|---|---|
| Magazine will not hold gas overnight | Dry or worn fill-valve or output O-rings | Oil the valve; if it persists, have the seals replaced |
| Weak shots, gas venting down the barrel | Worn nozzle or output seal | Reseal the magazine or gun; book a service if unsure |
| Sluggish cycling on a cold day | Low gas pressure from the cold | Warm spare magazines in a pocket; fire shorter strings |
| Gas spits back when filling | Over-filling the magazine | Fill for a few seconds only, then stop |
| Seals swollen or sticky | Petroleum lubricant used by mistake | Replace the seals; only ever use pure silicone oil |
If a fault survives fresh gas, a drop of silicone oil and a warm magazine, it is usually a seal that has reached the end of its life. That is a workshop job rather than a field fix.
When to bring it in for servicing
Routine care handles most things, but seals do wear out eventually, especially on higher-pressure CO2 guns. Some jobs need the magazine or gun stripped and the O-rings and valve seals replaced properly.
Bring it in for a reseal or service if you notice any of the following:
- A magazine that will not hold gas overnight even after oiling the fill valve
- Gas venting continuously from the barrel or valve
- A hissing leak you cannot trace by eye or by ear
- A steady drop in power that fresh gas and lubrication do not fix
Tom brought in a CO2 pistol last winter that vented every capsule within a minute. He assumed the gun was finished and had half-priced a replacement in his head. In fact a single perished output O-ring was the culprit, and a fresh seal had it holding gas again the same afternoon. A reseal is almost always cheaper than a new magazine, let alone a new gun.
Our workshop has been servicing gas guns for players across Kent and the South East since 2006. If something is not behaving, our repair and servicing team in Rochester can diagnose it and get you back on the field.
Frequently asked questions
Should I store airsoft magazines with gas in them?
Yes, for green gas magazines. Leaving a small amount of gas inside keeps the O-ring seals seated and pressurised, so they do not dry out and shrink between games. CO2 is different. Never store a magazine with a pierced, live CO2 capsule in it, because the high pressure sits on the seals constantly and wears them out. Use the capsule up and remove it.
How long does green gas last in storage?
A sealed green gas bottle keeps for a long time, well over a year, provided it is stored upright, cool and out of direct sunlight. It does not really go off. The bottle only loses pressure if the valve leaks, which is why storage conditions matter more than any date on the label. Sealed CO2 capsules last even longer.
Is green gas safe to keep at home?
Yes, with sensible precautions. Green gas is propane-based and flammable, so store it upright in a cool, ventilated space such as a garage or shed. Keep it away from heaters, open flames and direct sun, and never leave it in a hot car. The main risk comes from heat raising the pressure, so temperature control is the priority.
Why does my gas pistol lose power in the cold?
Because gas pressure falls as temperature drops. A cold magazine holds less pressure, so you get lower velocity and weaker cycling, and rapid firing chills the gas further mid-string. Green gas is more affected than CO2. Keeping spare magazines warm in an inside pocket and firing in shorter strings both help a great deal.
How often should I put silicone oil on a gas gun?
As a rough guide, a drop of pure silicone oil on the fill valve every few top-ups keeps the seals healthy. CO2 guns need it more often than green gas guns, because CO2 is a dry gas with no built-in lubricant, so many players oil a CO2 magazine every couple of games. Only use 100 percent silicone oil, never petroleum-based products, which destroy rubber seals.
Can I use CO2 in a green gas gun?
Only if the gun is specifically designed and rated for it. CO2 runs at far higher pressure than green gas, and a gun built for green gas can be damaged or made unsafe by the extra load on its seals and internals. Always check the manufacturer’s rating for your model, and if you are unsure, ask us before you fill it.
The short version: store your propellant cool and upright, keep the seals fed with pure silicone oil, fill without over-filling, and keep spare magazines warm in winter. Do those four things and a gas gun will reward you with years of crisp, reliable cycling.
When a seal finally gives up, do not write the gun off. Our Rochester workshop reseals and services gas guns for players right across Kent, and it is nearly always cheaper than a replacement. Drop it in during opening hours and we will get you back on the field.
