Thursday, May 12, 2005

How to find airgun leaks & what you can do about them

By B.B. Pelletier

How do you find a leak in an airgun? What do you look for? For that matter, WHERE do you look? We've talked about O-rings, seals and how Pellgunoil miraculously seals a gas gun. But I never told you how to find the leak in the first place! Now's the time!

I'm forever blowing bubbles...
...and so are pneumatic and gas guns that leak! Soapy water is the traditional way to find air leaks. Airgun repair shops keep a soapy solution around for this very purpose, and you can use the same method. Get some dishwashing liquid, mix it with a little water in a small drinking glass, apply the soapy solution to the places on your gun suspected of leaking. If there's a leak, you'll see bubbles forming in the soapy solution!

What if the leak is deep inside the gun?
Not all leaks are found by the first method, so there's another way to detect leaks that are deeper in the gun. Wipe a film of soapy solution across the muzzle of your gun with your finger. If the valve is leaking at the exhaust side, your muzzle will blow bubbles.

In a hurry & no time for soap? Try this!
If you're in a hurry, here's a fast way to find leaks: stick the muzzle in a basin of water. If it blows bubbles, the valve leaks. I've used a toilet bowl in a pinch (for testing airguns, of course!). Remember, you are putting only the muzzle in basin of water - not the whole gun or even the entire barrel!

Do NOT leave water on your gun
Guns and water don't mix well, so make sure you dry the gun completely after any of these tests. I don't think a towel will do a good enough job, so I suggest that you use an air hose or some other kind of forced air. Dry-firing the gun several times is a good way to dry any water that's in the barrel. After you're sure it's dry, wipe down the gun with a good oil. If it's a CO2 gun, shooting a Crosman Pellgunoil CO2 cartridge through the gun would not only be the perfect way to finish the after-testing maintenance, it might even seal the leak!

Sometimes, you can hear the leak!
Sometimes you can hear where a gun is leaking if it's a fast leak. You need to be in a quiet place, plus it helps to cup your hand around the gun parts you suspect of leaking. If the leak is fast, this is a quick way to pin it down.

What about sloooooooow leaks?
There are leaks so slow they are next to impossible to find in the traditional way. Like magnesium car wheels that become porous after driving on salted streets, there are airgun leaks that may never be found. You have to be reasonable. Most of my airguns hold their charge for years, but I have a vintage Crosman pump that loses its one-stroke maintenance charge in two weeks. The solution has been to pump it twice when I want to leave it a long time, and to check it every six months. So far, that's worked. Don't throw the baby out with the bathwater!

Let me know how you find leaks!


At August 14, 2005 2:35 PM, Anonymous Anonymous said...

I have a VERY BIg leak in my Daisy 15TX. When ever I put a fresh CO2 capsule it discharges the whole thing. Can you help?

At August 14, 2005 5:14 PM, Anonymous B.B. Pelletier said...

What you have is called a fast leak. Have you tried using pellgunoil yet? It can sometimes fix a fast leak, too.

You migh try a Crosman maintenance kit, which is essentially a powerlet with oil inside.

The point is to shoot the gun while it is leaking so the oil gets blown through the entire valve and coats all the seals.

Tell me what you've done already and where your gun leaks (read the posting again) and we'll see what more can be done, if anything.


At August 16, 2005 3:46 PM, Anonymous Anonymous said...

well thanks fopr the tips, I finally got it under control. I did'nt use the Crosman oil, I used an oil for singer sewing machines. I'm amazed that it does'nt fast leak anymore. I'm still looking in to see if there is still any little leaks. Thanks!

At August 16, 2005 8:43 PM, Anonymous B.B. Pelletier said...

Thank you so much for your feedback. I think I'm as glad as you are when things happen the way they should.

I didn't know Singer oil would work, but you can't argue with success.


At January 19, 2006 3:02 AM, Anonymous Alice said...

This is a stupid question but I am new at this. I bought a Crossman CO2 pistol and it is great. I fired off about 8 test shots and then when I went to put the gun away, I unloaded it and took out the CO2 cartridge, which never worked again.

My question: Can I leave a CO2 cartridge in even if I don't use the gun often and keep it in a case in a closet? It seems a waste to fire a few shots and then lose the whole cartridge. What is the best way to store a gun like this and still make the best and safest use of the various components?

At January 19, 2006 3:17 AM, Anonymous Alice said...

Sorry - my model is a Crosman 1008B. Cannot find anything in the manual that says if it is safe to leave the cartridge in or not. And if it is safe, what is the highest indoor room temp the gun can stay in and not have problems?

At January 19, 2006 7:02 AM, Anonymous B.B. Pelletier said...


You can leave the CO2 powerlet in some guns for years without damage or danger. I am testing a Crosman 2240 pistol right now and I've left it charged with the same powerlet for three months. I have other Crosman guns in my collection that have remained charged for several years. I once bought a Crosman model 111 pistol that had kept its charge for about 20 years.

The only guns where leaving a powerlet installed is not recommended say so in the owners manual. There are a few whose design is more fragile and they can develop problems if left charged. If there is no warning in the owner's manual of your pistol, I would say go ahead and leave it.


At January 19, 2006 1:37 PM, Anonymous Alice said...

Thank you SO much. Great website and information.

One last question. I live in a city but have a small backyward that is overrun by racoons. The city won't trap and take them away and I can't go outside with a shotgun either without scaring the whole enighborhood. Would a pellet gun deter or actually kill and/or seriously injure a racoon? I want to scare them off but don't want injured and angry racoons lying around the yard. What about plastic BBs?

At January 19, 2006 6:49 PM, Anonymous B.B. Pelletier said...


You know, I don't have any experience in deterring raccoons. Pellet guns will kill tham humanely, but that doesn't sound like what you want to do. My brother-in-law trapped six of them in a Have-A-Heart trap and drove each one about 20 miles before releasing it. That sounds like a lot of work to me.

Also, please be careful! Raccoons are prime carriers of rabies!

Maybe one of our readers has a little more experience than me. Have you spoken to your county or state wildlife services office about this?


At February 14, 2006 2:35 AM, Anonymous Anonymous said...

What do you do if the gun has some serious leaks in the gas tubing, can I just glue and seal the tubes back into their positions?

At February 14, 2006 7:30 AM, Anonymous B.B. Pelletier said...

What model gun do you have? Since CO2 is at 900 psi, gluing doesn't usually work. A new set of valve parts might be required.

Have you done the Pellgunoil fix yet?


At February 18, 2006 3:45 PM, Anonymous Anonymous said...

Hi, its a crossman 357 - 6 shot revolver, I recently purchased it- was told it was in good working condition, instead of taking it back to the guy i bought it from, i was sure I could fix it, but as I was removing parts the charged gas cylinder blew a few parts away, including the tubing.
Now when you place a fresh cylinder into the gun, it empties in a few seconds as the tubes are not sealed.

At February 18, 2006 3:49 PM, Anonymous Anonymous said...

No I have not tried the Pellgunoil.
I am not sure if this product is available in New Zealand.

At February 18, 2006 5:01 PM, Anonymous B.B. Pelletier said...

New Zealand,

You need serious help with that 357. Pellgunoil won't fix it. It needs a rebuild.

Are there any Crosman repair stations on New Zealand?


At February 18, 2006 5:08 PM, Anonymous B.B. Pelletier said...

Gamo 1250,

Get a good set of rings with the scope stop pin built in. The recoil from a Gamo 1250 isn't strong enough to bend a scope stop pin unless it was made from unhardened steel. I suspect you were using inexpensive (Gamo?) rings. They won't take that kind of stress.

B-Square or AirForce rings will be strong enough for your gun.


At February 18, 2006 5:11 PM, Anonymous Anonymous said...

I have thought about taking it into the shop but my other half is already upset about spending $ on what is now a pile of parts.
I have all the parts and know where they go, but just need the tubes etc sealed.

At February 18, 2006 5:16 PM, Anonymous B.B. Pelletier said...

New Zealand,

Okay, contact this guy, Rick Willnecker. Tell him where you live and ask for some technical advice.

If that fails, contact Crosman and do the same


At February 18, 2006 5:39 PM, Anonymous Anonymous said...

Thanks for your responses and time.

At March 14, 2006 5:34 PM, Anonymous Anonymous said...

When I put the co2 canister into my gun, it leaks and sprays everywhere and is empty in about 5 seconds. Is there supposed to be a rubber washer or a seal? I'm trying to fix it for a friend. It's a Crosman 357 air pistol. Might the oil work for it too?

At March 14, 2006 5:46 PM, Blogger B.B. Pelletier said...

B.B. is out of town. He'll answer your questions when he returns later this week (if no one else has already done so).

B.B.'s assistant

At March 17, 2006 9:52 AM, Blogger B.B. Pelletier said...

357 fixer,

It sounds like you are missing the seal that the powerlet butts against. It's a thin synthetic seal. I don't know if Crosman will sell them to the public, but you could ask.

If not, the gun has to go to a repair station.

I doubt the oil trick will help in this case.


At June 06, 2006 2:04 PM, Blogger lagbolt1138 said...

I have a Bengamin Sheridan HB17 air pistol which I use to scare off raccoons that are eating our garden. The pistol is only a year old, has been fired only about 50 times, is NEVER pumped more than 3 times (I don't want to kill), and now it leaks through the barrel. I can hear it. One shot it was fine, the next it was leaking. I called Crosman, they said oil it. The manual only has instructions for oiling pivots. What can I do at home? Do I need to send it way for service?

Any insight you could provide would be most appreciated.

At June 06, 2006 2:40 PM, Anonymous B.B. Pelletier said...


Have you stored your gun with a pump of air in it? If not, start doing that now.

Your problem is your seals are hard and dried out from exposure to the air. Oil the pump head by turning the gun upside down and opening the pump handle as far as it will go. The pump head will barely be visible at the end of the pump slot. Drop four drops of Crosman Pellgunoil or any PURE silicone oil (edible oil only!) on the pump head And work the pump handle for 30 seconds to spread the oil.. Don't use 3-in1, WD-40 or any household oil or the gun will have to be stripped and repaired.

After oiling, pump the gun eight pumps and shoot it with a pellet. Do that 10 times. Then put two pumps of air into the gun and let it sit for a day. In 24 hours, cock the gun and shoot it. It should still be holding air. If so, your gun is fixed. Store it with a pump of air in it at all times.

If that doesn't fix it, you can try the same procedure again, or write me and I'll tell you where to get it fixed. Stored with air in it, your pistol should last 30-40 years.


At June 06, 2006 2:59 PM, Blogger lagbolt1138 said...


Wow. Good stuff there. I will try it tonight. Thanks!

While I have you...another question.

My wife has difficulty with the pumping of the HB17. She's not nearly my size, so we’re considering a CO2 BB pistol for her on raccoon watch.

How long will a CO2 cartridge (CO2c) hold pressure in a pistol after installed? Using up an entire CO2c for just a couple of shots is wasteful and expensive. Since budget is an issue, especially on such a low use item, can you recommend some mfgrs or models to look at or avoid? It would be best to have something ready for use, than to waste time on set up.


At June 06, 2006 3:05 PM, Anonymous B.B. Pelletier said...

An airsoft gun will scare a critter without damage, while a BB can possibly break the skin.

You can buy a good automatic electric gun that runs on batteries for under $30.

Look under Airsoft and then under electric mini machine guns on the Pyramyd Air website.


At June 12, 2006 10:51 AM, Blogger lagbolt1138 said...


A quick follow-up on your air leak fix for the HB17 (see 06 June posting). The oil procedure you recommended worked perfectly. Thank you so much for time and expertise.

At July 18, 2006 2:07 PM, Anonymous Anonymous said...

i have a crossmen power master model 760, i've had it for 10 years and it just started leaking out the barrel and im stumped, any help would be appreciated

At August 05, 2006 6:11 PM, Anonymous Anonymous said...


I have a Crosman Model 73 CO2 rifle. I think it dates from 1976, and has probably never been oiled.

After years of sitting on a shelf, I tried to get it working again. When I insert a CO2 powerlet, most of the time I get a fast leak that empties the cartridge in 5 - 20 sec. I have tried to use WD-40 and some oil to seal the leak (not Pellgunoil), to no avail. Do you think I made the problem worse? What do you think I should try next?

Thanks for the great site.

At August 06, 2006 9:50 AM, Anonymous B.B. Pelletier said...


Well, the oil and WD-40 didn't do it any good. WD-40, especially, is very rough on fine working parts. It's great for drying distributor caps, but who has one of those anymore? I love the smell, but when I saw what damage the varnish it leaves can do to a fine firearm, I stopped using it altogether.

I would say that the best thing you can do now is to send your rifle to a good Crosman repair station. Here is the best:

Rick Willnecker Contact him at or call 717-382-1481.


At June 04, 2007 2:07 PM, Anonymous Anonymous said...

Hello! I have an old Crosman 760 purchased around 1976. It's still a good gun, but recently it's developed some kind of leak. The first shot is always fine, but after that, it won't hold any pressure and it's a really weak pffffft no matter how many times I pump it. Then I let it sit for a day or so and it's fine for the first shot again, but after that, no go. Is there any way to tell which seals or valves need to be replaced, where can I find parts and how do I go about it. I've already disassembled the gun about as far as I can but I think there are still some parts in the barrel. Thanks!

At June 04, 2007 2:31 PM, Blogger B.B. Pelletier said...

There are no parts in the barrel. The entire valve is housed in the pump tube under the barrel.

You can call Crosman and see if they will sell you the parts you need, or you can send the gun to an airgunsmith. I recommend this guy:

Rick Willnecker Contact him at or call 717-382-1481.


At July 24, 2007 6:01 PM, Anonymous Anonymous said...

i have a hahn 45 co2 bb gun its old i just recieve it from my grandpa i put a co2 cartridge in it when i go to shoot it leaks where the inlet is sprays out like and five seconds then its emtpy. what do i do

At July 25, 2007 6:28 AM, Blogger B.B. Pelletier said...

You get it resealed, then you never put another cartridge in it without putting a drop of Crosman Pellgunoil on the tip of the cartridge beforer it is pierced.

This place can reseal it for you:

Rick Willnecker Contact him at or call 717-382-1481.


At July 25, 2007 10:57 AM, Anonymous Anonymous said...

is this place in detroit michigan

At July 25, 2007 11:10 AM, Blogger B.B. Pelletier said...

Nope. It's in PA.


At July 25, 2007 11:22 AM, Anonymous Anonymous said...

can i fix it myself that to far to go

At September 22, 2007 10:20 PM, Blogger John said...

I have a Crosman model 1077 repeater rifle. It's been sitting for about ten years because it developed a fast leak so I just put it away. Now my neighbor is having that raccoon problem that it seems, everyone is having so we need to try harsher measures. He's already trapped 8 of the critters. Thing is, our township and county want nothing to do with them. They said to call private animal control people who, by the way, get big $$$ for their work! Town told us that you CAN NOT trap them and drive them to a remote location as it's a crime to transport wildlife ANY DISTANCE without a license. Private pro suggested .22 cals or 12 gauge. 2 am with neighbors sleeping 20 - 30 feet away.

Anyway.....want to get the gun working so as to put a little "scare" in them. Can't kill them cause we can't dispose of them without getting arrested so....where do I start with this leak thing? After I put the cart in you can hear it hissing.


At September 23, 2007 10:05 AM, Blogger B.B. Pelletier said...


NEVER use a pellet rifle to "discipline" an animal. It's cruel and inhumane. If you shoot them, kill them.

As for getting your rifle resealed, try this place:

Rick Willnecker Contact him at or call 717-382-1481.


At October 05, 2007 8:52 PM, Anonymous sam said...

got my hands on crosman 38t 177 air gun. I don't know much about it. I bought a box of 5 CO2 gas and pelts. Placed CO2 and took one shot at night, placed the gun on table only to hear hesssssssssing while watching tv. The CO2 gas gone. I took gun apart in the morning tried different things placing CO2 cartg till I used all. It is leaking gas and I can't find out from where? some gas came thrugh the cylender some through barrel. Please help Thanks....

At October 06, 2007 9:16 AM, Blogger B.B. Pelletier said...

Before you disassembled your 38T I believe it could have been fixed by the use of Crosman Pellgunoil on the tip of a new CO2 cartridge. However, at this point, the gun probably needs to be rebuilt.

This place can do the job:

Rick Willnecker Contact him at or call 717-382-1481.


At September 22, 2008 3:33 AM, Blogger The Big Bore Addict said...


Above you mentioned the Crosman maintenance kit.

I noticed that PA discontinued it, so I'm wondering if putting a few drops of Pellgun Oil on the inlet, & a couple on the cart do the same thing?

- The BBA -

At September 22, 2008 9:56 AM, Blogger B.B. Pelletier said...


Pellgunoil won't FIND leaks, but it often fixes them.


At September 24, 2008 5:00 AM, Blogger The Big Bore Addict said...


Yes I understand that, but I meant for FIXING leaks, not finding them.

That's my fault, I should have been more specific.

Pellgun Oil IS great stuff & HAS fixed a number of leaking guns of mine. But in my experience, usually just the slow or moderate leaks. Not the ones that completely empty a CO2 cart in a matter of seconds.

I have a couple of REALLY bad leakers like that, & while of course I don't expect Pellgun Oil to work every time & especially not on guns where the seals are totally shot, I'm just trying to find out what will give me the best chance.

The description of the cleaning kit says;

"Includes two Pellgunoil Lubrication Cartridges and 100 felt cleaning pellets."

Since Crosman doesn't say how much oil is in their Lubrication Cartridges, I'm just wondering if they are more efficient or will work better, as opposed to putting a several drops of Pellgun Oil on the inlet, & also a couple on the tip of a plain CO2 cart?

I've actualy saved some pretty bad leakers by doing that a few times.
It didn't work the first time, but the second time it seemed to slow down a little, & by the third or fourth time, it DID work. :)

So I was just wondering if the Lubrication Cartridges would work better, & save some guns that my method won't.

- The BBA -

At September 24, 2008 9:12 AM, Blogger B.B. Pelletier said...


I don't see much difference between the lube cartridges and just oiling the tip of each cartridge every time.


At September 25, 2008 3:10 AM, Blogger The Big Bore Addict said...


Yeah... That makes sense.

The more I think about it, how much oil is really in those lube carts? Five or six drops?
Even if it were more, my method would still eventually get the same amount of oil in the same places, within a couple of tries or so.

I guess it was just wishful thinking, hoping maybe there was something I didn't know about them, but the more I think about it, it's like you say... Either way, it's going to do the same thing.

Thanks for the input & bearing with my silly questions lately.

It's been a rough month, so my brain is scrambled right now, & I'm finding myself second guessing everything.

Thanks again,

- The BBA -

At October 29, 2008 8:48 AM, Blogger alexander said...

i have a crosman pro77 and everytime i put a c02 cartridge in it all leaks out and i get about 3 shots,i have tried everything what should i do?

At October 29, 2008 8:51 AM, Blogger B.B. Pelletier said...


Your gun has a leak that has to be repaired. A seal is bad. Have you always used Pellgunoil with every new cartridge? That can prevent this from happening, but sometimes the seals just fail.

Contact Crosman for repairs unless the gun is under warranty.


At November 01, 2008 7:59 PM, Anonymous Anonymous said...

I got an old crosman 38c from my dad put a co2 cartridge in and it all leaked out. so I'm soaking the cylinder with the air parts in tranny fluid this should swell the seals. but if it don't where is this guy in Pa? thanks

At November 02, 2008 6:50 AM, Blogger B.B. Pelletier said...

The seals in these guns do not swell by soaking in Pellgunoil or anything that doesn't destroy them. That's not how they work.

This is the contact info you requested:

Rick Willnecker in PA. Contact him at or call 717-382-1481.


At July 06, 2009 5:04 PM, Anonymous Anonymous said...

I have a Daisy Powerline 990, you can hear air leaking out when you pump it more than 7 times, it seems to be coming from around the chamber. How can I fix it?

At July 06, 2009 5:23 PM, Blogger B.B. Pelletier said...

When was the last time you oiled the pump head? Use Crosman Pellgunoil or 20 non-detergent motor oil, only.


At July 06, 2009 5:55 PM, Anonymous Anonymous said...

I put Hoppe's 9 Lubricating Oil on it about an hour ago. But it still does not work, should I try the other oils?

At July 06, 2009 6:07 PM, Blogger B.B. Pelletier said...

Well, Hoppes may have ruined the gun!

It may need a complete rebuild now.

That's why I specified Crosman Pellgunoil or 20-weight non-detergent motor oil. Nothing else works. Your owner's manual should have mentioned that.

Because it is a Daisy, only Daisy will repair it.


At July 14, 2009 5:47 PM, Anonymous Anonymous said...


I have a Crosman 357 Co2 powered air pistol. I used WD-40 on the end of one air cartridge before knowing what sort of harm it would do to the airgun (that was a stupid idea).

Now the airgun is no longer consistent with each shot I fire. i.e. I fire one shot and its perfectly normal, then I fire another shot and the velocity of the pellet goes down by half etc... But when I wait for about 60 seconds after each shot the velocity of the pellet returns to normal. I don't hear any leaks and I just got this gun about a month ago...

Would Crosman pellgunoil fix this problem? Or would this problem fix itself over time? What would you recommend?

At July 14, 2009 8:32 PM, Blogger B.B. Pelletier said...

I had this exact problem filming a shoot for American Airgunner today! The problem is not lubrication. It is the piercing needle that isn't puncturing the CO2 cartridge deeply enough. It leave a small hole the gas can eventually get through.

Either the piercing pin has to be replaced or you need to screw the cartridge in tighter.


At July 14, 2009 8:45 PM, Blogger kevin said...

Or you need to shim the bottom of the cartridge like I had to do on my crosman mark II since the piercing needle had been worn significantly. I put a doubled over thickness of paper towels at the bottom of the co2 cartridge, then put pellgunoil on the tip of the cartridge. After 3 cartridges the gun shot like it was new. I'm convinced that B.B.'s pellgunoil was as significant to this "fix" as adding the doubled paper towels to increase cartridge penetration.


At July 14, 2009 8:47 PM, Anonymous Anonymous said...

Good point! I'll give that a try. I think I might need to replace the piercing needle though because I don't hear that discrete hiss when I screw the cartridge in.


At July 14, 2009 8:53 PM, Anonymous Anonymous said...

Thanks Kevin! I will also give that a try without replacing the needle first. I thought the WD-40 contributed to the problem or messed up the seals badly... I'll have to give pellgunoil a try!


At July 14, 2009 10:04 PM, Blogger kevin said...

Anonymous with the piercing needle problem,

Please visit the link I provided. There's some interesting comments to your questions from experienced airgunners waiting for you there.


At July 15, 2009 12:17 AM, Blogger The Big Bore Addict said...


I would like to add that when using Pellgunoil, sometimes you have to go through a number of carts before it starts to work.

I had one gun that took 6 carts with putting pellgun oil on them before the leak finally stopped.

So, if it doesn't fix it the first time, don't give up.

Hope this helps,


At July 15, 2009 10:10 AM, Anonymous Anonymous said...


I can't seem to find that link you recommended. Can you post it again please. Thanks!

At July 15, 2009 10:36 AM, Blogger kevin said...

Anonymous regarding the piercing needle problem,

My apologies. I confused you with another airgunner.

I am going to give you a link though.

You posted your question under an article that B.B. wrote back in 2005. Not many airgunners check back on these old articles. Most are asking and answering each others questions in the "comments" under the most recent article that B.B. has written (B.B. writes a new airgun related article every day, Monday-Friday). Here's the link (you will need to copy and paste) that will always take you to the most recent article that B.B. has written:

Look forward to seeing you there!


At August 11, 2009 1:51 PM, Anonymous Anonymous said...

i have a 38t, hapve taken it apart to investigatet a full blown leak. I have two 0 rings that are bad. Looking for replacements. cannot find on the internet----


At August 11, 2009 2:21 PM, Blogger B.B. Pelletier said...

Check here



John Groenewold, PO Box 830, Mundelein, IL 60060-0830, (847) 566-2365

and here

Rick Willnecker in PA. Contact him at or call 717-382-1481.


and here

At August 12, 2009 8:29 PM, Blogger The Big Bore Addict said...

Anonymous with the 38T, post your email so I can contact you. I may be able to help.



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