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Airgun lubrication — pneumatics

by Tom Gaylord, a.k.a. B.B. Pelletier

Airgun lubrication — spring guns: Part 1
Airgun lubrication — spring guns: Part 2
Airgun lubrication — gas guns

This report addresses:

• What is a pneumatic?
• No. 1 lubrication need.
• A short pneumatic history.
• Which oil to use?
• Other lubrication.
• Wipe down.

This report was written for blog reader Joe, who asked for it specifically; but I know that many of our newer readers also found the information useful. Today, we’ll look at pneumatic guns. There are 3 very different types of pneumatic airguns — precharged, single-stroke and multi-pump — but I think they’re similar enough to cover all of them in the same report.

What is a pneumatic?
Pneumatic airguns store compressed air for one or more shots. Single-strokes get just one shot per fill and so do most multi-pumps, though there are some that do get multiple shots. Precharged pneumatics (we shorten the name to PCP) get many shots per fill.

Big bores, which are always PCPs, get the fewest number of shots per fill, but the smallbores (.177, .20, .22 and .25) get many. How many depends on the output power of the gun and the amount of compressed air that’s available (i.e., the capacity of the air reservoir).

No. 1 lubrication need
The most important reason to lubricate a pneumatic of any kind is to seal the gun. This is similar to gas (CO2) guns; but since pneumatics use air — which is thinner than CO2, their lubrication is extremely important. The seals in the guns are all sized to their jobs. In the case of o-rings, they sit in channels that assist in their sealing role; but without the right lubrication, all would be lost.

A short pneumatic history
Pneumatics are the oldest type of airgun, and their technology has evolved over more than five centuries. The first pneumatic guns used leather seals in all places to seal the reservoir as well as sealing the firing valve.

As time advanced, airgun makers learned how to lap (polish until smooth) valve faces of animal horn that is much better and less porous than leather. These valve faces would be hand-lapped to match the exact surface of the metal (brass or bronze) valve seats to which they were fitted. When the lapping job was finished, these valves would hold air much longer than leather. Leather was still used to seal the junction around the threads of the reservoir, so the guns still leaked down — but the amount of leakage was reduced by a significant amount.

[Note: Airgun designer John Bowkett determined decades ago that precisely machined stainless steel valve faces and valve seats work best of all, providing there’s enough lubrication and the machining is correct. The contact surface of this type of valve is extremely fine and narrow; but if it’s perfect, this valve will be very controllable. The downside is that valves made this way are still extremely labor intensive.]

Leather seals and horn/brass valves were still being used in big bore PCP airguns up through the 1920s. Smallbore PCPs didn’t come into being until 1980, when Daystate converted one of their tranquilizer dart guns into a .22-caliber sporting rifle they called the Huntsman. Daystate was the first company to build a modern PCP; and when they did, synthetic materials were both available and far better suited for pneumatic valves. At the same time, o-rings in properly cut channels provided the remainder of the sealing solution in place of leather — and the modern PCP was born.

Synthetic seals are less porous than animal horn and last far longer. They’re not as hard as stainless steel, so the mating surfaces of the valve do not have to be machined as precisely (they have a little give to accommodate slight imperfections in the valve seats). Synthetics make the modern PCP possible. And lubrication is what keeps PCPs sealed almost forever.

Leather seals in other pneumatics
Leather has been used for the peripheral seals in multi-pump pneumatics up to as recently as the 1950s. Just like the leather seals of old, the problem has always been how to keep the leather seals lubricated so they remain soft, pliable and doing their job. Oil was used originally in these airguns in the late 1890s. But times change and today we have better lubricants. Petroleum jelly will stay on the job many times longer than straight oil, so even the leather seals in your vintage multi-pumps can be lubricated for a long time.

Which oil to use?
That brings us to the big question of the day: Which oil to use? In this instance, there isn’t just one answer. For PCPs, the right oil needs to have a very high flashpoint so it isn’t prone to explode when subjected to high pressure.

I know of two instances in which petroleum-based oil or grease has caused an explosion in a PCP. One was a vintage PCP reservoir that was pressurized to around 800 psi. The interior walls of the reservoir were coated with grease to trap any dirt particles that might get in during filling. This is a common practice with such airguns; but this time the person who greased the reservoir used petroleum grease instead of organic-based (animal) grease. The reservoir blew apart at the soldered seam! Fortunately, no one was hurt.

The other instance was one I got from a news story, and the person involved was, unfortunately, killed when his modern PCP reservoir exploded. The article said he had apparently introduced regular household oil into the reservoir.

On the other hand, I’ve safely oiled PCP tanks hundreds of times with a couple drops of Silicone Chamber Oil through the air intake port. I put several drops into the fill port before the gun is filled. When the air blows in, the oil is atomized and gets on all the sealing surfaces inside the reservoir and valves.

The oil to use in a PCP is silicone chamber oil. For single-strokes and multi-pumps, the answer is different. For either of these types of pneumatics I use Crosman Pellgunoil. Neither of these types of pneumatics are pressurized nearly as high as a PCP, and Pellgunoil always does the trick.

Can other oils be used instead of Pellgunoil? Certainly. I’ve used Gamo Air Gun Oil in my single-strokes and multi-pumps for many years. I use it exactly as I do Pellgunoil for single-strokes and multi-pumps, but I do not use it in any PCP guns.

The thing about multi-pumps and single strokes is to keep their pump cups sealed and working well. These are the flexible pump heads that force air into the guns, either one time or several. They tend to get hard over time and lose their ability to seal, but keeping them oiled and in use frequently will prolong their service lives. Not using a pneumatic airgun is what really hurts it.

Other lubrication
For normal lubrication of moving parts, both Pellgunoil and Gamo Air Gun oil work fine. So do most gun oils, like Remoil. What you do not want to use is silicone chamber oil for this purpose because it doesn’t have enough surface tension to lubricate properly. Your parts will rub against each other and wear.

Wipe down
As always you can use the lubricating oils to wipe down your gun’s metal and wooden parts, but Ballistol neutralizes acidic fingerprints and lasts on the surface of metal far longer than plain oil. So, it gets my recommendation for this job. It also gets the nod for the insides of all airgun barrels.

Airgun lubrication is important, for the reasons mentioned in this 5-part report. Sealing is the biggest role lubrication performs, in all cases. We’ve looked at some very specific examples of products that should be used for the reasons stated. If you decide to substitute, you do so at your own risk.

author avatar
Tom Gaylord (B.B. Pelletier)
Tom Gaylord, also known as B.B. Pelletier, provides expert insights to airgunners all over the world on behalf of Pyramyd AIR. He has earned the title The Godfather of Airguns™ for his contributions to the industry, spending many years with AirForce Airguns and starting magazines dedicated to the sport such as Airgun Illustrated.

94 thoughts on “Airgun lubrication — pneumatics”

  1. I spent a couple years learning watch making. The oil scheme of watches is an art. To much is the worst thing. One thing I learned is the clean up. Basically if you can wipe the oil off with a rag. Then the oil was not between parts and only collection dust.

  2. G’day BB
    You try to make it hard to buy what you recommend: just joking!
    RWS Chamber Lube and Dropper $15…shipping to Oz $52.
    Total $67 vs $15, ouch!
    Cheers Bob

    • Bob, have you heard of Mac-1’s secret sauce? Tim will sell you what could be a lifetime supply for like $14, It’s 30 hydraulic oil with proprietary conditioners-his own special blend.I don’t know about PCP’s but I lube all my pump guns with it. Even got a rusty ole Crosman 140 pumping air after who knows how long.the quad seal’s still blown but that’s another matter and as soon as I can use both hands reliably I’ll be fixing it( a friend’s gun I’m fixing just so I can shoot it,well and he gave me a QB-36) At least you’d only have to pay the tariff once!


  3. B.B., I pulled out that M4-A1 Airsoft gun last night in an attempt to establish it’s manufacturer. All I could find was “made in China” which I believe most of them are.When the charging handle is pulled back there is a flap covering the breech that pops open, it also has a magazine in which there is a sliding door that opens to allow for rapid refilling. Any good guesses?
    Thank You for your and time and expertise Sir!


  4. Back about 1990I gotta job that sent me to Lake O’ the Pines in east Texas,I had money and wanted an airgun to get into trouble with. The one I picked happened to be a 1377 Classic-$40,with a sliding breech cover, at the time I considered pellets to be too expensive and awkward to load, so you guessed it. after only 3 months my pride & joy had slowly grown considerably weaker and I adjusted the value of my gun accordingly.One day a new crew member started waving a $20 in my face and I eventually caved in.within 2 hours he was back from town with a tube of Pell-gun oil and proceeded to teach me the most valuable lesson I’ve ever learned about airguns. 🙁


  5. B.B.,

    Please clarify, “put several drops into the fill port before the gun is filled.” Everytime?

    I have enjoyed and learned much from your reports on airgun lubrication.

    A suggestion for a future report is airgun noise. I experimented with one of Gunfun1’s long-barreled Crosman 1322s and was surprised at how quiet it was, even at 12fpe, compared to my less powerful and much louder Benjamin 397. Other than suppressors, the variables of valve opening and closing, discharged air volume, muzzle pressure, caliber and velocity must be important influences. The lack of noise is what first led me to airguns, and I’d like to understand it better.



    • RB, the longer barrel is actually using the air for propulsion whereas the shorter barrel allows the pellet to escape before all the pressure has been used, therefore not only wasting air but also creating excessive noise.It’s one of the reasons I wanted a 18″ barrel for my 2240, another reason is more power.Now, with all that weight out front I believe a ballast would seem to be in order which is one reason I wanted a butt-stock;solution-2400KT, allows for all this, in one order.Steel breech and other mods will be performed by yours truly, as cash flow allows


      • Reb,

        I agree, barrel length plays an important role in reducing noise for the reasons you stated.

        A Benjamin 397 is loud compared to the more powerful, 24″ barreled 1322. Why?

        As Gunfun1’s experiments have shown, there are other factors, too. Reducing velocity to subsonic makes an obvious and important difference. Heavy pellets are quieter than light ones, but I don’t know why. I like my Discovery a lot, but it is loud. I’m not interested in suppressors, but I am interested in other ways the gun might be made quieter. Reduction in power/different valve/hammer spring/or other changes might make a big difference.

        On a separate note, I really, really wish Crosman would build a multi-pump Discovery and/or Discovery with an onboard pump. It would be the world’s finest multi-pump/independent PCP.


        • RB
          Also I forgot to say that the adjustable end cap from a 2300S will work on a Disco. Here is the Crosman part number. 2300-124

          Also the way I set them is I adjust the screw all the way out. Then I shoot the gun and see what fps it shooting at. Then what I will do is cut a coil at a time off the spring until I reach the lowest velocity that I want the gun to shoot at.

          So lets say that it ends up shooting at 600 fps at the lowest setting with the screw all the way out. Then I can turn that screw all the way in and the spring wont get coil bind when I pull the bolt to cock it. And with the adjustment all the way in you should be real close to what the guns original fps was shooting at.

          So yes that is a way to quiet up the Disco’s also. And another benefit you can turn the power down when your inside or you can turn it up when you go outside. Quiet and tame inside. And rock’n roll’n out side.

          • After long deliberation I’ve decided instead of ordering a 2240, bunch of parts, co2, more .22 pellets…. Im going to get a jump on the stuff I’ll need for the talon, pump and .25 pellets, maybe the buttstock but 70$ for that little bit of plastic is ridiculous, it should come with the gun. I am getting a chrony with these things for testing the np, then I can write a part 3 velocity report. Bet your bungalow I’ll review the talonp when it gets in. Figured splitting the order will take some of the salt out of the wallet wounds, lol.

            • Good Luck with it! Still goin’ the poor boy route myself did you see the HPA chamber for the 2240 platform? My intention is to do that eventually.’Til then I’ll buy some CO2 as long as I can effectively hunt with it.


              • When I have money, i have money, but its few and far between. For the amount of shooting I do I cant rely on gas tanks, I go through them too fast. I have enough constant bills without my shooting being one of em, I’ve been limited to department store pumpers and the last few years doin springers, the whole while sprinkled in with bb pistols, time to get serious and spend the couple bucks to match my equipment with my enthusiasm. Chrony – ~$500 gun – then its time for the super shows. I’ll be shooting till Im done so Id like some pieces I can appreciate and hold onto. Not that the low priced stuff isn’t fun or worth keeping, I just get bored with things that are so easily replacable.

                • RDNA
                  I think the Talon P is a good choice for you from what I hear you talk about that you like in a gun. And yes if you got to watch your money that should be a good gun to get. Also something to think about as you progress and what to step up to higher dollar guns. The Talon P should be able to bring you some money to get to your next level of PCP gun. Or like you said hold onto it for along time.

                  And that long barrel and 1399 stock conversion on the 2240 and 1377/1322 pistols are fun little guns. They can take small size pests out to a fair distance. And they are great for mini sniping in the back yard. But they are kind of like a low budget gun that will perform good for the cost. And you get to say you made it the way you like.

                  I was wondering though. Have you ever got to shoot a PCP gun yet? Anyway I think you will be happy when you get one.

        • On your separate note, that ultimate gun exists today as the FX Independence and FX Indy (bullpup version). All the power and advantages of a PCP with an onboard hand pump to keep the reservoir topped off between shots. No more fiddling with bottles or putting the gun on the floor to pump it. I bit the bullet and am excitedly awaiting delivery of an Independence in .22. They are pricey for sure. Perhaps someday Crosman could produce something similar for less. Did I say I am excited?!

        • It sounds like your Benji is moving more air. When you think about it both the pumping system and valve are considerably larger so I guess that’s the answer or at least part of it and the lighter pellet leaves the barrel quicker.Anybody else please correct me or feel free to take it from there, I’m running outta brain power and educated guesses. but I’ll still be here


      • Gunfun1,

        Yes, Sir, I did build one! After you wrote about it, I put a Discovery barrel on a 1322. It was a fun and inexpensive experiment. With steel breech and stock 10″ barrel, the gun made 470fps with JSB 14.35 grain pellets for 7fpe with 10 pumps. The Discovery 24″ barrel raised the velocity to 535fps for 9fpe. 15 pumps gave 585fps for 11fpe, and 20 pumps gave 615fps for 12fpe. I’m not recommending anyone over pump a gun, but I did this time, and these are the results I measured. The rifle is very light and ergonomic, surprisingly quiet, and I am pleased with the power. Accuracy is a problem. Groups average 1″ – 1 1/2″ at 25 yards. Different pellets, temporarily mounting the front sight from my Discovery to change barrel harmonics, recrowning or trying a different barrel are possibilities. I have not measured it, but I’ve wondered if the twist rate is appropriate for this velocity. I remember you writing that the 1377 version was more accurate, and I may try that, too. This has been a fun learning experience, and I appreciate your writings about it.


        I was surprised how quiet and powerful it is.

        • RB
          I have to ask. Was you shooting bench rest? When I was testing for accuracy I was bench resting and here is the pellets that gave me the best results at 25 and 50 yards with the .22 cal. barrel. Oh and did you put one of the 1399 stocks on it?


          And I got my best groups using 10 pumps. I was getting around .875″ group at 25 yards and around 1.125″ at 50 yards. That was the .22 cal. gun with the above pellets.

          The .177 barrel liked these the best.

          With 10 pumps the .177 barrel was getting around a .750″ group at 25 yards and right at 1 inch at 50 yards.

          When I was testing for accuracy I had my 12 power sidewinder Hawke scope on the gun. And like I said above bench resting and I was only shooting 5 shot groups. So I’m sure I would of had bigger groups the more I shot. And the group sizes I just gave is averages. Some groups were better and some worse. But I find that happens on a lot of guns I shoot.

          But It sounds like you like it. And speaking of sound. On that set up try shooting the gun with out a pellet in it. Kind of loud that way isn’t it. then loud a pellet and shoot with the same amount of pumps and the gun becomes quiet.

        • I have over pumped a lotta guns the only one that has suffered ill effects was my 392, the exhaust valve seal came unseated about 1/4 of the way around, I used one of my blunted picks to work it back in until I can get one on order. I talked to Tim @ Mac1 about one of his exhaust valves and machining a valve to mail me. He wouldn’t do it so I’m trying to come up with my own solution for this problem,I’m thinking about doing away with the rubber all together something closer to a one piece design I have modified most of my guns and try to move/store more air with most of these modifications.Especially when I open reservoir space I feel justified in overpumping.Guess my 392 taught me a lesson about exhaust valves. Hmm stainless steel?


  6. First off good write up on lubricating pneumatics BB.

    And that would be a interesting topic about sound. But first thing is I would say that right of the bat that suppressors and such devices need to be left out of the conversation because that tends to be a controversial topic.

    Like what RB said. What happens to the report of the gun when you get the tune efficient. That is another aspect I look at when I tune a pneumatic gun. Be it a PCP gun, co2 or a pump gun. And its something I pay attention to when I test a pellet. Certain pellets are quieter with the same tune on the gun then other pellets.

    Also I got one of those dragon 100 dollar pcp’s. I have been talking back and forth with buldawg about his .22 cal. version he’s got. I got the .177 cal. version. And I hope I ain’t breaking the rules talking about it. I ain’t trying to sell it but just getting and giving info about the gun.

    But I found out something out messing around with it. The tune definitely makes a difference in noise on this gun. I got off work the other night and was messing with it in the garage and shot it with a Superdome on the factory tune at 1500 psi. All I can say is super loud. It startled me when the gun fired. It sounded like a .22 long rifle round discharging. It was pushing the 8.3 grn Superdome at 1100 fps. I couldn’t believe it so I shot again. The same.

    I adjusted everything so it would give the lowest fps velocity at the 1500 psi fill. Lowest the dang thing would go was 950 fps even with the 10.3 JSB’s. And yes still loud but not that crack sound anymore. So I cut about 4 coils off of the striker spring and shot both pellets again with everything still adjusted low. Finally got the gun to slow all the way down to about 650 fps with both pellets. And yes the gun was finally quiet. So I got it set now at about 850 fps with the heavier JSB’s and the sound is definitely respectable. Not as quiet as a Marauder but definitely a quiet gun now. And the gun at 50 yards bench rested is averaging about 1 inch groups. So I’m happy so far and the gun is easy to work on and seems to be a pretty solid build on the gun also. I never thought I would say that about a China gun. But so far I like it.

    • GF1, Happy to hear about your success with your DIY PCP,I’d like to hear a lot more about them as I have considered buying one myself.I’m definitely going ahead with my 2400 plan,which will probably eventually be my first PCP but a gun that needs the rough edges knocked off and a little elbow grease is very enticing so it won’t be far behind. U snoozeUlose!


  7. So this is silicone?

    This is what comes up with that link you provided above BB. And you said it is silicone. I just want to make sure. It said it was synthetic so I wasn’t sure. I have some but I thought it was just for springer’s or pump guns or co2 guns.

    If its silicone I will start using it then in my PCP guns.

  8. B.B.,
    I have a dumb question. For a PCP that have a removable air cylinder, where is the Fill Port?
    I know the Fill Port for a Daystate Huntsman is at the front of its air reservoir where I connect the fill adapter.

  9. This is the same issue I had with my Cobra Snake oil it says synthetic but no mention of formulation,I finally bit the bullet and put 10 drops in my QB-36 and let set overnight, crossed my fingers and fortunately no bad news.Working the lever, the anti-bear trap and loading with 1.25 hands is very difficult and has this gun sitting most of the time now but I’m still working on the other .75


  10. B.B., Just outta curiosity’s sake what do you think about this stuff?http://ri.search.yahoo.com/_ylt=A0LEV1U8y3xTbwsAUapXNyoA;_ylu=X3oDMTEzbmo5OGU2BHNlYwNzcgRwb3MDMgRjb2xvA2JmMQR2dGlkA1ZJUDMwNF8x/RV=2/RE=1400716221/RO=10/RU=http%3a%2f%2fwww.super-lube.com%2fsilicone-ezp-281.html/RK=0/RS=IC4VuRXG_rqEXcbhjAvuYeLrQvs- In the comments there is one guy that said it’s excellent for firearms there are also other comments about it being very heat tolerant.


      • I suspect it might be safe… Last time I read the CRC Handbook of Chemistry&Physics, Teflon was only affected by molten alkali metals (which led to the conclusion that my mother’s cooking was dis-associating salt into elemental sodium and chlorine — she could ruin a teflon pan in just a few months [Then I encountered a pot I’d left in a partly filled sink for a few weeks… the half that was below water level was shiny clean aluminum, while the other half was pristine teflon coating])

        I don’t think an air-gun is going to contain molten alkalies. The Teflon component might even be helpful for the non-pressurized components.

        • I was just trying to help poor ole Bob in Oz out with the tariffs on his import export goods, Geez, I thought $8 was robbery!.But if anyone else benefits during the process then all the better.Thanks Wulfraed! This time I did my homework first.


  11. Hi B.B.

    Great series on lubrication!

    I pulled my Discovery out of the closet after having not shot it for months only to find I had put it away with minimal air after a shooting session. When I filled it, it immediately leaked like a sieve through the fill adapter, and won’t seal. I suspect corrosion is to blame.

    I now have the fill adapter removed, but not sure where to go from here. Can the adapter be disassembled without special tools and the corrosion hand sanded away with very fine sandpaper, or does it need to be sent away for repair?

    If I were successful in taking it apart for cleaning, I suspect there are moving parts, so am wondering if a light coat of silicon grease would be appropriate?

    I thought of simply trying to lube the fill adapter with silicon oil and see if it begins to seal, but given the suspicion of corrosion, I’m thinking this would be only a temporary fix, if at all.

    Appreciate any suggestions!


    • Bilol,

      Who says there is corrosion? That’s very uncommon in a PCP. I have never seen it.

      You probably had some dirt on a valve seat or o-ring. I hope you didn’t disassemble the gun, because it contains a micron air filter that must be seated right to work. If you did not disassemble the gun, just put some silicone oil in the fill nipple and fill it again. Then try to dry-fire it as fast as possible as the air is leaking out. That will sometimes blow the dirt off the seals.

      No silicone grease is needed for the inside of this gun.

      Lloyd, what else can you tell Bill?


      • Hi BB,

        I couldn’t remember where the idea of corrosion came from, or if I dreamed it.
        I just did a Google search and found this example of corrosion.

        I didn’t disassemble the gun; only emptied the air reservoir and unscrewed the fill adapter.
        Can the fill adapter be easily disassembled and cleaned, assuming corrosion is involved?

        I’ll try your suggestion with the silicon oil and rapid dry fire, and will report back. Hopefully I have some silicon oil on hand….


        • Bill,

          By the fill adapter you mean the female fitting that is on the end of the air hose? Those are generally made of stainless steel and don’t corrode. There are brass ones that work the same but they also don’t corrode.

          If you mean the airgun I would rather defer to Lloyd Sikes who works on more Discoveries than I have ever seen.

          And do try my solution. It works 75 percent of the time.


          • I tried this with my Benjamin 3120, a pump gun and believe it or not that’s how I finally got it to seal enough to shoot a few shots.Talk about coordination!that was back in the day. My problem was a deformed intake valve which isn’t far from being fixed.I hope! Then it’ll be time for the pivot link rivet.


          • Sorry for the confusion of terms. I’m not talking about a fill adapter or anything associated with a fill hose. I’m referring to the fill port on the Discovery’s air cylinder. The entire inch to 2 inch port assembly unscrews from the fill end of the air cylinder. The port itself doesn’t look like it disassembles easily.

            Curious though, from the link I provided, the term fill adapter is used, and the picture looks similar to what I might imagine a dissassembled male fill port might look like. Am I off on this?

            BB, with my work schedule, I won’t get to your solution until the weekend, assuming I’ve got that silicone oil, but I will get to it and let you know if I can raise your success percentage.

            Thanks again!

        • Hi Edith,

          Hoping you can help. I found that I have some of the following product on hand, and am wondering about its use in PCPs.

          Item Code: WEBLUBE [PY-A-141]
          Webley Air Gun Lube (WEBLUBE)

          It doesn’t mention silicone, but says, among other things, that it’s a “synthetic … that provides lubrication under wide extremes of temperature.”

          Would this be safe for PCPs and use for fill port lubrication, ie when under high pressure?

          Thanks, Bill

        • Hi BB,

          Unfortunately, your solution did not work. There’s definitely something wrong with the fill port.
          I removed it from the air reservoir, put drops of silicone oil in both ends, manually moved the center part of the port valve, reassembled it, and tried filling with my Benjamin pump. I heard the valve in the port click, but was only able to pressurise the fill hose. The reservoir took no air.

          I then tried my scuba tank, and after many attempts, was able to get it to slowly take air. I rapidly discharged the reservoir — twice. It still leaks and only reluctantly accepts air.

          I’ve convinced I’m ready for Lloyd’s next recommendation, but alas, have heard only crickets thus far.

          Thanks for the help,

          • Hi Bill,
            I just caught up with your question. The problem is probably either corrosion, as you suspect, or a broken o-ring inside the fill nipple. The fill nipple is often called a quick disconnect (Q.D.) or Foster fitting. They are all the same thing, and luckily are pretty universal. All paintball guns have them too. The thing that makes it specifically a “fill nipple”, though is the check valve that is inside it, or in your case, the leaky check valve. You can remove the fill nipple from the air tube adapter by using a 9/16″ wrench on the tube adapter and a 7/16″ wrench on the fill nipple. The fill nipple has a standard 1/8″ tapered pipe thread on it and might be hard to break loose, but it will definitely come apart. After it is apart there is only one moving part, a little check valve about 3/4″ long that looks like a cut-off nail with an o-ring on it. You will probably find rust and corrosion on it, especially if you fill with a hand pump very often. When you compress air to 130th of its original volume with a hand pump, it still has all of the original moisture in it. In humid weather, that is a lot of water and not many fill nipples are made from stainless steel, so there is the source of your corrosion.
            But anyway, try and clean it up with a Scotch Brite pad, and check the condition of the o-ring. If it cleans up ok, reassemble it using some regular plumbing Teflon tape on the fill nipple threads. The Teflon tape goes only on the tapered pipe thread. About 3 or 4 tight wraps is enough.

            If the repair doesn’t work, and you have a paintball store anywhere nearby, your problems are solved. Just buy a new fill nipple (with check valve) and install it into the tube adapter. The fill nipple ought to be in the $10 price range.
            I hope that gets you shooting again for the holiday weekend!

            • Thanks for responding with the great advice, Lloyd.

              Unfortunately, no shooting or gun repair this holiday weekend.

              I’m looking at the removed fill port now. It’s 1.875 inches long from foster tip to the back end face, and it appears to be a solid, one-piece cylindrical machined assembly. There is a knurled section close to the front, for finger turning ~ 1/2″ wide, where the foster fitting joins the circular front face of the port assembly.

              Excluding the foster port tip, the entire assembly is cylindrical. 1/4″ forward of the back end face is an O ring that sits in a channel nearly flush with the circumference.

              There are no wrench fittings at all on this fill port, so nothing can be taken apart with a wrench.

              On the back circular face of the assembly is a smaller circular recess cutout that the check valve moves through.

              Near the back end is also a small hole drilled into the side through the diameter of the assembly (visible on the outside and in the recessed area) less than 1/32 inch from the back face of the assembly.

              Through the hole is a thick pin, which is bent outwards in the middle recessed area. This bend presumably provides a friction fit for the pin in its channel to keep the check valve from falling out of the assembly.

              One could likely punch the thick pin out to gain access to the check valve for removal, but it would be very challenging without special tools to get at any corrosion inside the recessed area of the probe once the check valve is removed.

              This fill port was the original which came with my Disco.
              My instinct is that the best option at this point is to find a replacement fill port.
              What do you think, Lloyd?

              Thanks again,

              • Bill,
                Do you have a very old Discovery? The one-piece unit that includes the male foster, the tube adapter with o-rings and the check valve with retention pin is something that I have never seen. As you suggest, I think ordering the entire fill port assy and adapter from Crosman might be the best thing to do. Item 37 in this exploded parts view from the Crosman site is what I think you need.


                • Hi Lloyd,

                  Yes, I have an old Discovery. I didn’t buy when it first came out, but I’ll wager it’s been at least a few years. I don’t recall exactly when it was purchased.

                  Ok, I’ll look into buying a new value, and thanks for the link to Crosman.

                  Appreciate all the help, Lloyd, BB!

                • Hi Lloyd,

                  I figured that since I was buying a replacement fill adapter anyway, might as well try to disassemble my old one for educational purposes.

                  It is quite simple compared to Crosman’s replacement–the main housing and foster fill tip are one machined piece. I drove out the pin keeping the check valve secure in the housing, and removed the check value.

                  There are only four main pieces to the entire fill assembly. Referring to Crosman’s exploded diagram of item 37 as a reference, the first piece is the main housing and foster tip (similar to 37A+37C excluding the check valve), which as I mentioned is one solid machined piece.

                  The second and third pieces are the check valve (37C) and a small thin plastic (not rubber and not shown in 37) o-ring around the shaft of the check valve which seals the check valve against the main housing air intake hole.

                  The fourth piece is the outer (single) o-ring (37B) though 2 are shown in 37B.

                  Interestingly, the plastic check valve “o-ring” is recessed in the middle allowing the circular end of the check valve (left end of check valve in the picture) to seat down into the plastic “o-ring”.

                  Turns out that a quarter of the plastic check valve was completely broke away. This plastic is relatively thin and rigid. I’m surprised it provided an air-tight seal. I’m reasoning that it was the broken piece that was jamming the check valve movement, preventing travel to allow air intake, and also preventing sealing due to part of it being broken away.

                  There is some slight corrosion on the check valve stem, and part of the plastic “o-ring” appears fused to both the check valve shaft and the housing air intake port. I should be able to carefully hand sand away the remaining plastic and corrosion and replace the plastic with a suitably sized rubber o-ring.

                  Any comments or suggestions? I’ve waited this long; no need to rush ahead if you have wisdom to pass along.

                  I’m assuming that the replacement rubber o-ring won’t be critical as long as it fits snugly on the check valve shaft and seals the air intake port?
                  I plan to use the finest grit sand paper I can find to address the corrosion and plastic.

                  Thanks again,

                  • Bill,
                    Now that you have described it more, that one piece unit is definitely something I have not seen from Crosman before, but they have made an awful lot of stuff. You can surely try an o-ring to replace the plastic washer, but generally, harder o-rings (90 duro) will perform better in check valve applications than soft ones (70 duro). But if you can pick one up in the plumbing dept at Lowes, no matter what the hardness, give it a try.

                    A fairly simple device, right? A scotch brite kitchen pad will probably get the metal parts as clean and smooth as they need to be.

  12. B.B.,

    I am sorry to ask what may seem like a dumb question, but when you say, ” I’ve safely oiled PCP tanks hundreds of times with a couple drops of Silicone Chamber Oil through the air intake port.” are you referring to the tank that attaches to the air gun where you fill it with air? If you can send a photo, it would be greatly appreciated. OR, if you send me your email address and I will send you a photo of the spot that I think you are referring to.

    Thank you.


  13. I have a styr LG110 and getting to the “fill nipple” is not really possible. Can I put some air chamber fluid into the cylinder inlet port? Thus, putting air chamber fluid into the cylinder should blow the air chamber fluid into the gun when I attach the cylinder to the gun.

    What do you think?

    Thank you.


    • Todd,

      I think you are worrying about nothing. Why put anything into your reservoir? Is it leaking?

      To put oil in, it has to go in at the place where the air enters the reservoir. If that is what you mean then, yes, that’s how it is done.

      But again, why do it? If the gun is working it’s best to leave it as is.


  14. Thank you for your reply. I have no troubles with my guns. I was just trying to make sure they are well maintained. I will take your advice and leave them alone.

    Thanx again.


  15. Once again, you’ve provided just the info I needed! I’m glad to know that I can use the RWS Air Chamber Lube inside my AirForce Spin-Loc tank. It’s developed a 100psi/day leak at the valve stem, and I plan to add a couple drops of this lube to the inlet port to hopefully seal the leak. (I already tried dry-firing the gun about 15 times, and have hit the valve stem 5 times with a rubber mallet, and neither had any effect on the leak.)

    Thanks for your wisdom, Tom!!!

  16. I know this is an old blog post, but I’ve been reading up on the RWS Diana Model 45 (old model)… similar story as others have… I bought mine from a pawnshop about 14 years ago.

    Also re-educating myself of general lubrications, because I haven’t done much with airguns the past 4 years.

    I’m curious what brand of “lithium grease” would you recommend these days… as there are all sorts out there, especially the “white”, and aersols, etc… I just want to avoid anything that isn’t recommended.

    My first air rifle was a Beeman FX-2, and it has a leather seal… I want to disassemble it and re-lube it… should be a good candidate to try the lithium grease on.

    I disassembled my Model 45 several years ago because it was smoking a real lot… local airgunsmith (Chuck Trepes from Precision Airgun in Maple Heights Ohio) said that it smelled like “Dri-Slide”… sadly Chuck pasted away in Feburary this year… loved his airgun shop–my favorite place to go shopping !

    I forget exactly what I used on the leather after I cleaned it all up… may have been Neatsfoot Oil, or a mix of it, or maybe just chamber oil… that was 14 years ago.

    I used a Maccari replacement spring, shorter than the original spring, but works great.

    Ken H in Ohio (AirMojo)

      • Thanks BB Tom !

        I must’ve stopped at part-9.

        So you don’t recommend lithium grease for leather-piston guns now ?

        The brand/make is what I was really curious about for my FX2 springer.

        Ken H in OH (AirMojo)

        • Ken,

          Yes, I do remember lithium grease and it does work well. I lubed my Diana 27 with it. But in a more powerful rifle like the 45 I like a grease that eats the vibration and Tune in a Tube does that.


          I don’t have any special brand for lithium grease. Whatever they sell at the auto parts store is what I use.


          • Hmmmmmmmm… that looks like the red grease that I use on my O-Gauge trains, called “RED “N” TACKY” by Lucas Oil Products… recommended by other model train hobbyists.

            Says on the grease gun cartridge “a high quality lithium complex grease fortified with extreme pressure (EP) lubricant additives that inhibits rust, corrosion and oxidation setting it apart from similar greases”.

            I wonder…

            Ken H in OH (AirMojo)

              • Thanks Tom!

                Always interesting trying to keep up with the latest trends in our hobbies… even though it does get kind of confusing !

                I really enjoyed your Model 45 blogs… I don’t recall having any major issues when I disassembled and re-assembled mine… maybe I just forgot… but I do know that I did not take enough photos… yours were very helpful !

                Ken H in OH

                • By the way, I did use JM’s Black Tar on my Model 45’s spring when I worked on mine… there really isn’t any vibration… I also used JM’s replacement spring, which is shorter, but I don’t recall how tight the spring guide was… I probably put some moly on the spring guide.

                  I get some velocity jumps, probably from me adding a few drops of Chamber Lube, since the rifle was sitting of several years.

                  But it seems to average around 750 fps with CP Lites.

                  I’m thinking of giving this air rifle to my younger brother (who’s 55!), and want to make sure he knows how to take care of it… but I’m starting to love this rifle !

            • AirMojo,

              Here is a list I found of Almagard 3752 equivalents:

              Timken Premium All Purpose Industrial LC-2 Grease
              Castrol 4020/220-2™
              Castrol 8060/220-2™
              Chevron Delo® EP 2
              Chevron RPM Automotive
              LC Grease EP-2™
              Citgo Lithoplex MP2™
              Citgo Premium
              Lithium EP 2™
              Conoco Phillips Super-STA® 2
              Exxon Mobil Ronex MP™
              Exxon Mobil Unirex EP 2™
              FAG LOAD220™
              Fuchs (Century) Uniwrl 2™
              Lubrication Engineers Almagard® 3752
              LUBRIPLATE® 1552
              Mobilgrease® XHP 222
              Pennzoil® Pennlith® EP 712
              Pennzoil® Premium Lithium Complex 2
              Petro-Canada Multipurpose EP 2™
              Royal Purple® Ultra-Performance® 2
              Shell Albida® LC 2
              Shell Retinax® LC 2
              SKF LGWA2™
              SKF LGEP2™
              Texaco Starplex® 2
              Unocal 76 Multiplex Red™


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