by Tom Gaylord
Writing as B.B. Pelletier

This report covers:

  • Mahesh from India
  • Good advice
  • Do precharged pneumatics leak down?
  • Do Sheridan Supergrades leak?
  • What have we learned?
  • You don’t need to rebuild your springer!
  • Yes, ATF sealant is a miracle lubricant
  • Summary

I was supposed to do the velocity test of the Umarex Fusion 2 repeater today, but something nudged it out of place. Actually someONE!

I get emails from my Godfather website all the time and the questions are sometimes asked in such a way that I don’t understand them. So I answer something else — and not what the person wanted to know. If these people were blog readers there would be no problem, but they aren’t. So all the stuff that’s obvious to all of you is brand new to them.

Mahesh from India

Blog reader, Mahesh, tried to fill a used Crosman Challenger he had bought with a hand pump and was told by the seller that the hand pump he used — AND GOT 15 SHOTS WITH — was not adequate to fill that airgun. He should use a scuba tank. Guys — if the balloon fills with air it doesn’t matter what puts it in there!

Of course the hand pump is adequate to fill a Challenger PCP! The Challenger was designed to be filled by a hand pump! Either the seller didn’t know what he was talking about, or he knew he had sold a leaky airgun and was intentionally lying. Mahesh also said his airgun leaked down overnight after a fill. Now, if it does that at all (hold the air until it leaks out overnight) it will do it regardless of how the air is put in. I told him to put some silicone chamber oil in the fill port the next time he pumped up the gun and it will eventually hold air. He might have to do it several times, but when the leak takes overnight it’s NOT a bad seal. It’s a dry one. If it leaks out in an hour the seal is bad.

Then somebody on the blog told him he might need to cock the gun to fill it from empty with a hand pump. Thank you for telling him that, but that wasn’t his problem. His problem was his gun leaked down overnight.

Good advice

That piece of advice (cocking a pneumatic before filling with a pump) is good for many precharged pneumatics. Their hammers rest against the end of the valve stem under some spring tension, keeping the valve from sealing completely and allowing air to leak out if they are filled slowly with a hand pump. A scuba tank blasts air in so fast that it shuts the valve against the slight hammer pressure.

Do precharged pneumatics leak down?

Yes and no. Yes, some of them have very slow leaks. I once had a Daystate that leaked down over a week. It was resealed several times to no avail. When that happens the problem is probably not the seals. It’s leaking somewhere else. It can be an imperfection like a small pinhole in one of the metal parts or it can be an imperfection left over from machining. 

On Monday of this week I started a report on the Crosman Challenger PCP — the same rifle that Mahesh is having problems with. The last time I shot this rifle was 11 years ago in 2009, when I wrote a 5-part report about it. After Part 5 of that report, on November 25 of 2009, I set the rifle aside and have not touched it since. It was still holding air when I picked it up again last Friday to start writing the report. PCPs don’t all leak. 

Do Sheridan Supergrades leak?

Everyone should be familiar with the Sheridan Supergrade, which is really the Sheridan model A multi-pump pneumatic air rifle. It’s widely regarded as one of the finest, if not the very finest, multi-pump ever made. And, unless it is cocked, it will not hold air when pumped.

Sheridan Supergrade right
Sheridan’s Supergrade is the Rolls Royce of multi-pumps. It must be cocked before being pumped.

The last time I shot my Supergrade was sometime in June of 2018. That’s over 2 years ago. But when I put it away I filled it with two pumps and then slowly lowered the hammer with the bolt.  Today I cocked the rifle and pulled the trigger. It’s still holding, after all that time. After trying it once I oiled the pump head with Crosman Pellgunoil, cocked the rifle, pumped it twice and slowly lowered the hammer with the bolt. Pneumatics don’t all leak.

Find a Hawke Scope

What have we learned?

We have learned that leaking is not common for pneumatics — for any of them. When they do leak it isn’t always their seals that are bad. Sometimes they just need to be lubricated so the seals are fresh and pliable. Lubricating the seals is a part of pneumatic maintenance.

We haver learned that some pneumatics have hammers that hold their firing valves open when the guns are uncocked. If these rifles are cocked, the valve can seal and it is possible to fill the reservoir slowly with a hand pump.

You don’t need to rebuild your springer!

I got an email from a guy who wanted to know where the instructions were for rebuilding a certain spring piston breakbarrel air rifle. Why? Well, he bought a new piston seal and wanted to install it. Why? Well — who knows? And that is my point. He probably wanted to do something with the airgun he had, but what did he hope to achieve? If you work on an FWB 124 there is a lot that can be done. If you work on a Wang Po Oompherator XDP, who knows where you are starting, so who knows where you can go?

You don’t need to rebuild every spring-piston airgun, regardless of what you see on You Tube.

“Well, So-and-So said he rebuilt his and he shot a half-inch group at 50 yards with it. I watched his video!”

Guys — did you ever hear of editing? I will not name any names but I remember an episode of American Airgunner in which the big bore we were “testing” leaked so fast that our takes could only be 25 seconds long. We would get set to film, fill the rifle and the instant the fill hose was disconnected and the guy ran out of the frame with the tank we started filming. You can add a lot of loud heavy metal music and quick cuts to that and make it seem like art, instead of the travesty that it is!

If you have to ask me for instructions on how to disassemble a spring-piston air rifle I have one piece of advice for you, “Keepa your hands off!” I share a lot of disassemblies with you in this blog and I know you are curious to see what is inside. But knowing how to shave your head with a straight razor doesn’t make you a brain surgeon! Spring piston airguns seldom need rebuilding when they are just months out of the box. Whatever happened to just breaking them in and learning to shoot them? I remember Gamo rifles that were horrible when new and delightful after 3,000-4,000 rounds had gone through them. I owned a Beeman C1 that I watched through the entire process — from new and stiff to becoming a smooth shooter.

Once a guy asked me to recommend an air rifle to him. I recommended something that was well-made and easy to cock and shoot. A month later he asked me why I didn’t recommend the Beeman Crow Magnum. I knew the guy was 5-feet 6-inches tall and weighed about 130 lbs. I didn’t think he would enjoy a breakbarrel rifle that took 40 percent of his body weight to cock. If you are an expert at reading between the lines, maybe you can figure that one out. I think I know and it rhymes with simoleon.

Yes, ATF sealant is a miracle lubricant

Boy — have I even been ’round the henhouse with this one! Some guy will contact me — afraid he has to have his CO2 rifle repaired and I tell him about automatic transmission fluid sealant. When I do one of three things happens. He blows me off as a whacko and goes in search of some valid technical advice, or he tries it and I never hear from him again because his problem was solved or he tries it and, to his utter amazement — it works! Those guys usually contact me again to let me know that it worked. I knew it would, but I’m glad they let me know. I have reports from a dozen or so success stories, plus several on this blog plus I have fixed 15-20 leaks of my own. 

transmission sealer
This stuff works on pneumatics as well as CO2 guns.


What this report has really been about is common sense, which my late aunt used to say, isn’t very common. Don’t just shoot your airguns. Maintain them! And don’t feel the need to totally redesign them before you know how they work!