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!