Why Does My BB Gun Leak CO2?

Why Does My BB Gun Leak CO2?

I’d say this is arguably the most common problem when it comes to BB guns and can be mightily frustrating!

The symptoms are this – you load a 12 g CO2 canister into your gun (or the bigger 88 g with a rifle) and take a few shots. You then store it overnight and come back to it the next day only to find it’s either empty or almost empty.

How do you prevent this from happening all the time?

Why Does a BB Gun Leak CO2? A BB Gun will most likely leak due to a problem with the seal. A quick solution to this is to tape any CO2 canisters before they are inserted and also lubricate the seal itself.

Why Does a BB Gun Leak CO2

The CO2 canister that you have inserted into your pistol or rifle contains pressurized gas. This gas is doing everything it can to get the hell out and the only escape route for it is the tiny hole made in the top of it when you initially screw it in.

Now, carbon dioxide molecules are small so they don’t need much space to escape. In fact, they are only 5 Angstroms wide. That’s 0.0000000005 of a meter! My point here is if they have an opportunity to escape, they will.

Another reason it can happen is that the shape of the top of the CO2 canisters that you use can de-form the seal slightly. This doesn’t happen overnight but over a long-time and typically only if you’re using the same type of canisters over and over again.

You won’t be able to see the deformation visibly, but it’ll be there. You may notice the leaking more if or when you switch to a new type of canister that has a very slight difference in its shape.

So, is it possible to create a seal that will prevent the release of any carbon dioxide? Well, in a word, no. All CO2 powered guns (whether they are BB guns or pellet guns, it doesn’t matter) will leak CO2 over time. The only control you have is the rate of loss, so you just need to minimize this the best you can.


How Can I Fix It?

If you notice, over time, that your CO2 canisters are giving you fewer shots than they used to then it’s probably time to address the problem.

Typically, there will be two types of CO2 leaks. You will either have leakage through the valves or seepage due to a seal problem. Or, you could be really unlucky and have a bit of both!

So, what can we do about this? If your leakage is slow then it’s more likely to be a seal problem. If you can literally hear the gas escaping, then it’s more serious and could well be to do with the valves.

Well, if you’re not sure where the leak is coming from, concentrate on the seal first. This is actually where most of the problems are so check this out and only if it doesn’t sort the problem out, then look at the valve possibility.


Seal Leaks

Firstly, get everything out on a table in front of you.

This will include the gun (err obviously), some plumbers tape (usually Teflon), a nice new CO2 canister and some lubricant. For this, I’d recommend a silicon-based spray.

Now, if you don’t have any of these items I’ve included links below where you can check the current price and purchase if you like.

It’s a bit annoying buying the silicon spray initially as it’s more expensive than you think. But, it’ll last you ages and you’ll find other gun-related uses for it, don’t worry!

Step 1 – Lubrication Of The Seal

Lubrication Of The Seal

I don’t know why but that title sounds like something a film would be called. “Harry Potter – The Lubrication of the Seals”. Hmm, I think I need to get out more.

Anyway, turn your pistol down so you can clearly see the seal where the CO2 cartridge is inserted into. The little pin that will pierce the canister is tiny but it shouldn’t be too hard to find (see my pic above).

Most pistols will have the CO2 canister located in the magazine but rifles (although it does vary of course) can have them in the stock.

Before you do this next bit, make sure your gun is on some old paper if you’re doing this inside or alternatively do it outside if conditions allow. If you’re inside, just ensure there’s a bit of ventilation. Now, get your way-too-expensive lubricant and spray the seal with it. Do a little more than you think it needs. It won’t do it any harm and you can wipe-off any that will no doubt end up everywhere else. If married, try not to get the lubricant on the interior walls or you’ll be dealing with a much more serious problem when your better-half discovers it.

This isn’t a one-time thing. Try and remember before you load a new cartridge to give the seal a quick spray. I keep my spray right next to the spare canisters so I don’t forget. I still manage to forget sometimes. Sometimes on purpose. It doesn’t matter though, just remember the next time as the more you do this the better though.

Step 2 – Taping the Cartridge

Taping the Cartridge

“Harry Potter – The Taping of the Cartridge”. No, see it doesn’t work with that one.

Right, now that your seal is lubricated and your wife’s nice wooden coffee table has a shiny new coat to it, we’re going to work on the CO2 cartridge itself.

Now, I think I know what you’re thinking – am I going to have to do this every single time I load a new cartridge in? Well, probably yeah. It might sound like a pain in the backside but actually, it adds about 15 seconds to it when you know what to do. Yes, I did actually time myself doing it.

The fastest was 7 seconds and the slowest was around 30 but that was because I dropped the tape onto my jeans and it picked up loads of cat fur.

Anyway, get your small bit of tape and wrap it around the to top of your canister a few times, covering the top bit as well. You don’t need that much and yes, it will be a bit fiddly at first.

What I’d recommend is when you’re watching television or YouTube one day, just plonk all your unused canisters on your lap and tape them. You’ll be able to do it blind-folder after a few goes. Some people then give the top of the canister another spray of the way-too-expensive Silicone lubricant but really this should be just before you load it. Personally, I don’t think you need to do it but give it a go if you like.

But hang on, why are we doing this again? Ah, good question. So, wrapping the tape around the top of the canister will ensure your CO2 cartridge fits nice and snugly into the seal. If your leakage is coming from this seal, this will definitely make a difference. I’ve seen it work too many times to think otherwise.

So, what do we do now? Simple really, have some fun with your gun – test it out. You’ll discover that your gun holds your gas longer over a 24 hour period than it did before!

Unfortunately, if the leak is fast – then it is most likely coming from inside, perhaps the valve. There isn’t a quick fix for this that I’ve seen really work. Although they are quite rare it can happen but when it does you’re going to have to make the decision to either take it back to the dealer to fix (which might be costly) or just bite the bullet and buy a new one.

You could try and fix it yourself but I really wouldn’t recommend spending your time on this. The cost of repair can easily be a good percentage of the cost of a nice new shiny pistol so most people go for the latter option when this occurs.


What Else Can I Do?

As boring as I feel for saying this, regular servicing of your pistol or rifle will help it shooting consistently for some time. I’m the type of person who doesn’t really maintain their weapons if I’m honest. I’d rather be outside shooting than inside oiling stuff.

I’ve been pretty lucky over the 40+ years of gun ownership that I’ve not had too many problems. Sometimes, you just get unlucky with the gun, it’s a dud and it’ll break – no amount of servicing would have helped.

However, if it doesn’t take too long and you can easily incorporate it into a shooting system then I’m more likely to do it. I don’t spray my seal every time I shoot. Even though the way-too-expensive Silicone spray can is right there. I don’t have an excuse, well I do, I think I’m just lazy. But, my advice would always be this. If it’s a cheapie then just go out and enjoy it. If you’ve spent a few hundred bucks on something though, yes – look after it.

An analogy is expensive cars. If you bought a $100 wreck you most likely wouldn’t clean it, right? What about if you bought a $100,000 Ferrari 458? Anyway, I’m drifting a bit – apologies, I do this way too much.

Happy shooting, stay safe and be lucky.



Firstly, if your gun is actually smoking, then this is probably something else. Best check out my article here on this subject! Or, if you’ve noticed that your air rifle is inaccurate – check out the article here which might help.