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Education / Training Things you can do to make your new airgun better: Part 2

Things you can do to make your new airgun better: Part 2

by Tom Gaylord
Writing as B.B. Pelletier

Part 1

This report covers:

• CO2 facts
• CO2 is a self-regulating gas
• The temperature thing
• Piercing pin problems
• Chilling bulk-fill guns to fill better
• Crosman Pellgunoil
• Automatic transmission stop leak
• Getting more power from a vintage CO2 gun

It took me long enough to get back to this report! I guess the SHOT Show and some other things just busied-up my schedule. But, this afternoon, I was installing a CO2 cartridge in a gun and had a little difficulty…when it hit me — I need to tell the readers about that! So, today I’ll talk about CO2 guns just a little.

When airgunner Jennifer Cooper Wylie asked for this report on my facebook page, I think she was looking for tuneup tips. I’ll give them, but mixed in will be some common maintenance tips, as well. We’re looking at CO2 guns today, and it’ll be helpful to remember what we know about CO2.

CO2 facts
CO2 is a refrigerant gas that expands as the temperature increases. When it expands, it increases in pressure when it’s in a confined space.

It’s also a gas that sublimates (changes from a solid to a gas without first becoming a liquid). It can be a source of thick, heavy fog used for theatrical effect without any special equipment being needed. Solid CO2 is simply placed in an open container like a bucket or tray and allowed to outgas. The dense fog flows out and hugs the floor because CO2 is heavier than air. If there’s water in the container, the outgassing speeds up, because water transfers its heat much faster than thin air.

CO2 is extremely cold in its solid and liquid forms. When it changes to gas, it does so by absorbing heat from its surroundings. Hence, as a CO2 gun fires, it gets colder. This chilling effect lowers the pressure of the resulting gas, so a gas gun fired rapidly also rapidly loses velocity. Since CO2 is used to power repeating airguns, this chilling effect needs to be taken into account. That’s why I allow a minimum of 10 seconds between shots when I test the velocity of a CO2 gun.

CO2 is a self-regulating gas
As a CO2 gun is fired, the liquid inside the cartridge (or the gun, itself, if it’s a bulk-fill gun) evaporates to replace the gas pressure that was used by the shot. At 70˚F, CO2 evaporates to a pressure of 853 psi. Just imagine that CO2 liquid expands 900 times when it changes to a gas. That’s why just 12 grams of CO2 liquid provides enough gas to power a gun for many shots.

In the old days, shooters thought their CO2 guns were leaking down fast. Many actually were because of the bottlecap CO2 cartridges then in use. But they were also experiencing a loss of velocity because they were shooting their guns rapidly and experiencing the chilling effect. Nobody talked about the chilling effect of CO2 in 1960 — people just chalked it up to gas leakage.

bottlecap CO2 cartridge
Crosman used this bottlecap method of sealing their cartridges for some time in the 1950s and ’60s to avoid patent infringement.

The temperature thing
Okay, let’s get on to today’s report. First, let’s talk about this temperature thing. It works both ways. On a cold day, when the ambient temperature is less than about 60˚F, a CO2 gun will chill with each shot and will not recover as fast. The colder it is, the slower the gun shoots. That’s why CO2 guns are not recommended for hunting in colder climates.

But it also works the other way. As the temperature rises, the gas pressure increases until you get what we call valve lock — too much pressure inside the valve for the striker to open it. I remember back in 2009 when we were filming a segment on action pistols for American Airgunner, and all our guns stopped working. We were filming in the Catskill mountains on a summer day where the temperature was just 85˚F. Normally, that’s an ideal temperature for a CO2 gun, but the guns that weren’t being used had been left on a table in bright sunshine — where they heated up to well over 100˚F. That’s when they all quit. When the second gun stopped working, I recognized what had happened and put the table in the shade for 30 minutes. After that, they all became operational, again.

Piercing pin problems
While filming this same segment, I found a couple guns that would fire one powerful shot and the next one was very weak. If we waited for a full minute, the next shot was powerful again. This wasn’t due to the gun chilling with the shot. This was something else.

When I removed the CO2 cartridge from the problem gun, I saw that the piercing pin had barely pierced the surface of the CO2 cartridge. It should have made a pronounced hole. The face seal in this particular gun was so thick that it prevented the piercing pin from piercing the cartridge as deeply as it was supposed to. Piercing pins are all the same at the factory, but there can be some variation in the thickness of synthetics used to make seals. Seals can also be made from different hardnesses (durometers) and that can cause the seal to not compress as it’s supposed to.

The solution was twofold. First, when we pierced the next cartridge, we put extra torque on the piercing screw to push the cartridge harder against the face seal. That squashed the seal down a little more. Then, we backed off on the piercing screw a small amount (1/4 turn) after the cartridge was pierced. That gave the gas more room to exit the cartridge.

This two-part approach worked in a limited way. That particular gun still took longer to recover from each shot than other guns, but the recovery time was now down to a few extra seconds instead of a whole minute. By repeatedly doing this procedure, you can eventually squash the thick face seal enough that the problem goes away entirely. This was the problem I had yesterday with the CZ P-09 pistol, and I fixed it exactly as I just described. If you shoot a lot of CO2 guns, you’ll eventually encounter one with this problem. Now you know how to deal with it.

Chilling bulk-fill guns to fill better
Bulk-fill CO2 guns are guns that are filled from an external tank instead of a throwaway cartridge. More equipment is involved, and it takes a few seconds longer to fill the gun, but the result is a gun that shoots 50 shots for 5 cents instead of 50 cents. That’s an almost 10-times reduction in the cost to shoot! Once I found that out, I became a lifelong advocate of bulk-fill CO2 guns.

But there are some things you have to know. When cold CO2 liquid enters a warm airgun reservoir, it immediately flashes to gas and increases the pressure inside the reservoir. Before long, the pressure in the reservoir is equal to the pressure inside the bulk tank that’s filling the gun. When that happens, the liquid stops flowing.

Chilling the gun before a fill lowers the temperature of the reservoir. Even when the liquid flashes to gas during filling, the temperature inside the reservoir is still lower than the temperature inside the CO2 filling tank, so the liquid continues to flow much longer. As a result, you get a higher percentage of liquid to gas inside the reservoir. This increases the number of shots you get per fill from about 30 for a room-temperature fill to 50 for a chilled fill.

But there’s some danger with this procedure. If the airgun is too cold, the percentage of liquid to gas in the gun’s reservoir can rise above 80 percent. When that happens, the space inside the gun for the CO2 to expand to gas is reduced, and that can have only one result — gas pressure rises. If the gun’s temperature rises like those action pistols we put in the sun, the pressure can exceed the strength of the materials used to build the gun. Then, the gun explodes!

So, chill your airgun or reservoir with this in mind. Either shoot the gun immediately or don’t fill it this way. A gun filled too full and left to sit is a time bomb whose clock can run out at any time.

Crosman Pellgunoil
I learned about Crosman Pellgunoil from Crosman repairman Rick Willnecker. He told me that he used Pellgunoil on every gun he resealed and that it’s impossible to use too much. When put on the tip of a CO2 cartridge or in the fill connection of a bulk-fill gun, the oil is blown into the gun’s valve where it gets on all the seals and o-rings, sealing them tight against gas loss.

Rick told me that many times when a customer sent him a gun for repairs, he first put some Pellgunoil into it and it sealed immediately. He still replaced all the seals because that was what the customer wanted, but he told me to give it a try. The opportunity came very quickly.

Edith and I used to attend a local flea market that was held in the parking lot of the local mall every Sunday. Once each month, they had Super Sunday and the number of stalls increased dramatically. A couple weeks after talking to Rick, I went to a Super Sunday and found 2 Crosman CO2 single-shot guns. One was a model 187 (.177) and the other was a model 180 (.22). They’re the same except for caliber. The seller told me they both leaked, but I knew Rick could reseal them so I bought both for $40, as I recall. When I got home I decided to try Rick’s suggestion, and he had given me some Pellgunoil sample packs to test.

I put Pellgunoil on the tips of 2 cartridges (each gun uses 1) and installed them. Both guns started leaking, then stopped suddenly. The 187 is scarce, and this one happened to be in excellent condition. I sold it for $100 but kept the 180. I still have it today, and it still holds gas indefinitely! I haven’t shot it in several years, so the cartridge that’s in it has been there for at least that long. I just pulled it out of the closet and fired a very powerful shot! Folks, that’s a testimonial to the benefits of Crosman Pellgunoil!

Automatic Transmission Stop Leak
But there’s something even better than Pellgunoil — Automatic Transmission Stop Leak. I wrote about this in a report titled, Neat fix for bulk-fill CO2 guns. That report was published 18 months ago, and the vintage bulk-fill pistol I fixed with that fluid still holds gas today. In fact, it has been holding for the past 18 months. Several naysayers warned that the seals would swell up and dissolve, but that hasn’t happened. And that gun was one I bought several years ago at an airgun show for very little money because it was a leaker! I couldn’t fix it with Pellgunoil, but this stuff did the job several years later. If it hadn’t worked, the gun could still have been resealed.

Getting more power from a vintage CO2 gun
Okay, Jennifer, here’s a tip for you. Many vintage CO2 guns have adjustable power that their owners overlook. All the Crosman bulk-fill rifles and pistols have these adjustments, but even some of the guns that use CO2 cartridges have them, too. The Crosman Mark I and II pistols have a power screw in front of their frame, as well as 2 different stops for the cocking knobs; the Crosman 180s have a tiny Allen screw that’s reached through their cocking knobs. Even the S&W 78G and 79G pistols have power screws below their muzzles.

So, boosting the power of your vintage CO2 gun may be as easy as turning the power screw higher. That can be a most welcome discovery when it applies to a vintage gun that you already enjoy.

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.

56 thoughts on “Things you can do to make your new airgun better: Part 2”

      • BB, quick question &/or advice. I have recently purchased both a Crosman 2240 and Crosman 1322.
        Out of the box when I shot the 1322 the front sight assembly and the pivot pin blew off the end of the pistol. With the 2240, also out of the box I couldn’t sight it in, it kept shooting right. I inspected the pistol and noticed the bolt and barrel were not aligned that the barrel was curved (bent) to the right. I also own a 1377 and have never had a problem with it out of the box and to this day is accurate with no malfunctions. Have you heard of any concerns with Crosman quality control as of late? I am not seeking to Crosman bash just trying to find out what is going on and if the quality problem is common and or re-occurring?

        Thank you for your opinion?

  1. We would freeze the nitrous bottles we used for our race cars to aid in transfer filling before the nitrous fill stations came out with a pump.
    And the bottles still filled better when chilled with the nitrous fill stations also.

  2. B.B.,

    I thought I recalled you waiting a minute to a minute and a half between shots when velocity testing CO2 guns, at least some of the time. This fits with what I’ve found with my CO2 testing — otherwise I get slightly lower velocities. Is the 10 seconds you mention just for testing rapid-fire?

  3. B.B.

    Just some pennies and twocents to add.

    I used to shoot my FWB C62 on CO2 with refillable “cylinders” before converting it to HPA.

    There’s a set of useful tools for filling CO2 – digital scales, gloves and eye protection.

    Always use gloves! Leather ones are quite ok to avoid frostbite. Well-chilled cylinders are -18 and escaping CO2 may well be below -60. Frosbites are not the thing to dream of. That is why eye protection is a good thing too.

    In case of CO2 cylinders, producer always marks it with empty weight and filled weight. For my FWB it was 363 g with fill weight of 73 g (100 cm3 of CO2 in liquid phase). So it’s easy to check if the cylinder is full on the scales and in case of overfill (rare thing, but still it happens) simply bleed a bit into the air.

    One more visual tip that seems to work – when cylinders are chilled down to -18 C (most modern freezers work on that temperature, some give -24 (my case) or even -28) they are covered with hoarfrost. Once liquid CO rushes into the cylinder, it starts to thaw and you can actually see the fill level. Once the hoarfrost is off – cylinder is most times full. Check on the scales and if OK rub it with WD to get rid of the moisture. If not – freeze it over and try once more. 45 mins are enough for deep freeze and 20 secs enough to fill the cylinder.


    • Duskwight,

      You are correct that weighing the cylinder is a safety practice. I used to do it until discovering that I could control the fill at least as accurately by controlling the temperature of the fill vessel.

      Yes, frostbite is a very real problem. I have gotten it (slightly) when filling a removable cylinder on a 10-meter pistol.


  4. B.B.

    I had always thought that the condensed CO2 inside my fire extinguisher and commercial soda CO2 vessels was liquid although when it is dispensed at a high rate it appears to be ‘powdery’. Early in the article you state that CO2 goes from solid to gaseous without becoming a liquid. Later you refer to liquid?

    Initially the two bottles were setup opposite of each other. The fire extinguisher uses a siphon tube to dispense solid/liquid? to the base of a fire. The soda style vessel dispenses only gaseous CO2 from the top. I had both bottles set up with the soda dispenser style valves with syphon tubes. If I were to need gaseous CO2 I just turn the bottle upside down.

    My friend pilots a Bonneville land speed vehicle that holds the record for ‘Fastest Four Cylinder In The World’…. Including land, water, and air…. When we were discussing some characteristics of compressed gas I learned something very interesting… When N20 is used on a street vehicle or drag car it is only used for a few seconds at a time. When attempting a land speed record the Nitrous is used steadily for a loooooong time. The problem they had to solve was the Nitrous would cool off and lose pressure just as you have described here. Their solution is to charge the area above the liquid with a regulated source of Nitrogen or compressed air thereby keeping pressure constant and dispense the liquid/solid at a constant rate..

    Many ‘Paintballers’ add an ‘anti syphon’ tube inside CO2 cylinders to tap off only gaseous CO2. Introducing liquid into the firing system is inefficient and will reduce FPS due to its density.

    I always find you writings interesting and informative. Thank you.



    • Greg,

      It is liquid inside thee cylinders. That is because of the temperature of thr cylinder. I just mentioned sublimation as an added point. Guns that used solid CO2 have been made, though the solid melts to liquid once inside a container that’s sealed.


    • In order for CO2 to liquify it needs to be under pressure. It won’t liquify at atmospheric pressure.

      Solid CO2 at atmospheric pressure goes from solid to gas without a liquid phase. Such a transition is called sublimation.

      At about 88 degrees Fahrenheit CO2 in a cylinder under pressure becomes a supercritical fluid. As BB mentioned the pressure will increase rapidly with a rise in temperature. If temperature gets to high – Boom!

      • I should have also explained that 88 degrees Fahrenheit is called the critical temperature for CO2. At that temperature, regardless of pressure, CO2 won’t form into a liquid and a gas phase.

  5. I would love to find a Crosman 187 at a flea market. That was a good find.
    I love the my 180 and would love to find a 187 with the adjustable trigger. In my backyard I usually shoot my 180 at half cock which is quieter and uses less gas. It is just as accurate on half cock, just shoots a little slower. I do the same thing with a Crosman Mk 1 and 2.

    David Enoch

  6. B.B.

    You said your Crosman 180 was stored with the pressurized CO2 cylinder installed in the gun. Everything I have read in the manufacturer’s instruction manuals say that CO2 guns should not be stored under pressure. So I’m confused about this. If it’s OK to store the gun pressurized with CO2, why do the manufacturer’s say don’t do it? If it’s not OK for the gun, why do you do it?

    • Charles,

      The design of airguns has changed over time. The older guns are safe and even benefit from being stored with CO2 in them. Some of the newer guns cannot take the constant pressure and do need to be discharged. And there is a safety issue with a charged gun, since it will shoot anything that can be put in the barrel.


  7. CO2 guns that are left charged are like the powerful battery operated power tools that I use everyday. They are always ON, and adherence to common sense will prevent accidents. BB, I still have the o-rings from one of two Crosman 150’s soaking in the Bars Stop Leak reccomended in the blog since you wrote about using it. They still haven’t dissolved. I did reseal one of the 150’s just last month but the stop leak fix kept it going for over a year.I agree with flea markets being the best places to find old airguns. Both the 150’s came to me like that , and I have less than 50 bucks into them. In fact, one of them came as a bundle , with a Crosman 130 and 105 . None worked but I had fun repairing them during this most miserable winter we’re experiencing here.

    • Robert,

      Your soaking of o rings for this long in Bars Stop Leak is very interesting to me. After B.B.’s blog on this fix endorsed by DAQ the negative buzz from pp’s (Pessimistic Predictors) was loud and plentiful.


      • Kevin: I don’t participate on the internet airgun forums .I do read some of the topics and comments, and saw negative comments you mention. After a few years of reading the information that some of these potato heads dispense ,it becomes obvious that the ones who make the most noise like to generate drama to sell their stuff and services. At least if the Bars didn’t work for someone who was hesitant to disassemble the gun, it wouldn’t be ruined by an attempt at it, that might beyond their personal skill set. Also,I like to personally test products I might use for something. I soak building materials in water, and expose fasteners I use to the elements. I learned a long time ago call backs due to product failure are what I call negative work.

  8. B.B.,

    There is a lot of useful information and tips in this article that could be reorganized into an informational pamphlet that could be sent out with orders to customers buying a CO2 airgun or airsoft gun.

    David H

  9. To All
    BBs explanation and use of trans stop leak is accurate in that it does help tired seals expand and seal when pellgun oil did not work. The reason that in an air gun it works and does not cause seals to disintegrate is due to the fact that there are no parts in an air gun that are rotating on the seals at any significant rpms or back and forth movements. Trans stop leaks work by softening and swelling the rubber of the seal’s and hence the non sealing seal suddenly seals as good as new again, but add a rotating shaft or a shaft that is being moved in and out on that seal at constant repetitions and that seal that now been softened and swelled up to seal on the shaft will have its life become very short lived. So while it is a very good solution to fix tired old seals in an air gun it is not a good substitute or cure for worn or hardened seals in auto trannies or car engines because a rotating shaft or moving will cause that soft and swollen seal to be destroyed in a very few number of miles which is usually within a couple hundred mile after being put in the failing component. I know this from 45 years of experience from people that used it to get their improperly shifting or leaking trans or engines to shift right or stop leaking oil only to find that in a couple hundred miles their trans or engines now would not shift at all or were leaking three times as bad as they were before the put the stop leak in the component.

    The stop leak does not dissolve the seals as some have said but it does soften and swell the rubber so that the rotating shaft or moving shaft it is sealing quickly wears the now soft and swollen rubber away to the point that it is a much looser fit on the shaft than it was before the stop leak was added, so as long as the seal has no part rotating or moving in and out of it during normal use it will indeed revive an old hardened seal to work like new for indefinite periods of time.


    • I had a ’81 CB-650 that I got used in ’92 that the forks leaked on and I talked to my buddy at the Yamaha shop about rebuilding them, he said here get this fork seal oil with O-ring sweller-$15. Worked like a champ! That’s why I was advocating the tranny sealer so adamantly.

      • Reb
        The fork oil you got from the bike shop that had the stop leak/seal sweller in it was most likely at a much lower concentration than what is sold as trans stop leak.

        How long did you own and continue to ride that bike with that oil in the forks. I know even now a new set of seal are only 10 or 15 bucks and are very easy to replace and I can swap a set of fork seals on any conventional forked bike in less than an hour. So to drain and refill the forks with that seal sweller oil was half the job of just replacing the seals and would have cost no more money than the oil did to start with.

        I can only attest to the number of auto trans I overhauled after they were filled with stop leak and all the seals in those trans were disintegrating from the rubber being softened and swollen to the point that the rotating shafts were tearing them and creating more issues than they fixed. This was also 15 years plus ago so it is very possible that the formulas today are far improved just as motor oils are better now than 15 years ago so that the stop leak oils work better and don’t swell and soften the seals as much now as they did 15 plus years ago.

        I would be one of the first to use it to seal an old air gun especially if new seals are not readily available, but if parts are available then it just is not in my nature to place a band aid on a wound that can be healed with new parts.

        I most certainly will never put any thing close to bars leak or stop leak in any of my vehicles as I have just seen to much negative effects from doing so when it is far easier and cheaper to pay the piper now than have to pay him later. Paying him later will cost two to three times as much, but then being a mechanic I could never afford to pay someone to fix my cars for me when they broke so if I could not fix them myself I would be walking. I have no idea how people can pay thousands of dollars to get their cars fixed as I never had that kind of money to pay so I learned to do it myself. I guess that is why warranties today are from 5 to 10 years and 100,000 miles or more. It is also why finding qualified mechanics/technicians today to fix the new techno wonders rolling down our roads is getting more and more difficult since the manufactures are not willing to pay them anything close to what their knowledge and skills are worth. This May will be my 40th year as an ASE master certified automotive technician and since I no longer work I will finally let my certification expire.


  10. As it happens, I just took out my 1077 for the first time in years. It held gas from the old cartridge, and I can’t believe what I was missing. This is a fantastic gun. Doing carbine style, snap-shooting really sharpened up my technique overall, and the gun is as accurate as any of my others at my distance. Due to unfamiliarity, I somehow managed to shoot off 120 rounds on a 12 gram cartridge before realizing it, but probablyI didn’t notice because my distance is so short. On the other hand, this is one instance of how the laws of physics can be bent. Lauren somehow managed to fire her Makarov pistol in Michigan’s Upper Peninsula when it was 0 degrees and didn’t notice any problems…

    I’m curious about how much pressure to apply to pierce the cartridge. At first, I was tightening them for all I was worth. But then I thought I read a blog post that says that excessive tightening will crush the seals, presumably damaging them. So, I stopped turning as soon as I heard the escape of gas, sometimes hard to hear. Now it appears that with certain thick seals, you want to crush them down. But will that harm normally sized seals?


  11. I’m so glad the tranny sealer worked out so well for many airgunners here! I have long been told that transmission fluid was the best way to restore luster to vinyl and rubber parts on vehicles but My Dad always ordered rubber dressing from the auto-magic rep that would come by his dealership so I never used it myself but watched others use it on their vinyl roofs and tires with a cringe,wondering if there would be any ill effects such as seen with armor-all and other silicone based restoration products. I’ve still got the bottle I was gonna fill that jack with, somewhere. I can’t recall who it was that was so concerned for my well being but the experiment was aborted when I went into the hospital in mid-April. I bought my first used Co2 gun about a week ago along with the first tube of pellgun oil in years( VL Triton II paintball) I think it’s gonna be a fun passtime and cut down on walking back& forth to check my targets with it’s .68″ holes and I’m not sure how they’ll feed through a hopper but muzzle loaded marbles seem to have about 10-15 fpe. When it warms up enough I’ll get some Chrony results and also let ya’ll know how they feed.

  12. For everyone’s information BBs statement about CO2 being a solid is what is commonly known as DRY ICE and can be dangerous if mixed with water in a closed container as the rapidly expanding gases will cause a violent explosion which can cause serious damage and/or injury to people and the surrounding environment.

    So use caution if working with dry ice and water in the same proximities.


      • Reb
        So now I know who created all that ruckus years ago at Disney world in Florida as I have a good friend that used to be a chef in the contemporary motel back when DW first opened in 1972 and the Hxll we raised there and fun we had will always be some of the best times in my life.

        Most people do not realize that Disney World is it own self sufficient operation and has its own power plant, water works, sewage and trash disposal and also all the food you eat there at the motels and fancy restaurants is grown, slaughtered and processed on site as the Disney World you see above ground there is 1 1/2 times as much underground that you never see. The lagoon is one huge concrete bowl that serves the campground area and the two waterfront hotels located there. They actually sell there excess power to Florida power and light.


  13. BB- I don’t think that I wrote my question clearly enough, so this is what I meant– 1 ) my co2 gun has been using pellgun oil. After long use, It starts to leak gas. 2) I use transmission stop leak oil. The leak stops. 3) Should I return to pellgun oil, or continue to use TSL as a pellgun oil substitute? Ed

  14. BB
    How about heating the tank instead of chilling the gun? What temp difference between the bottle and the gun is optimum? I know the idea of heating a co2 cylinder sounds stupid but I don’t mean taking a torch to it or putting it in an oven!

  15. I just want to thank all you guys and gals for sharing your experience and wisdom with us that only recently have come to the game. I’ve been bouncing around the internet trying to find straight talking folks who know what their talking about. great blog.

  16. Charliebee,

    Welcome to the blog and to airgunning.

    This blog is for folks like you who want to learn more about airguns in general. We are very tolerant of different views here and we do not enforce staying on topic. This site is read by many parents with their children, so we try to keep is a G-rated site.


    Tomorrow I will present Part 3 of this particular report.


  17. Hello BB,

    I have a Benjamin 2600 pistol that is have a velocity problem. For the first several shots the velocity seems to be ok. As I continue to shoot, leaving about 15 seconds between shoots the velocity dramatically decreases and remains consistent until the CO2 cartridge is almost empty. The last 5 to 10 shots are at full power again until the cartridge is depleted. What is going on? It doesn’t seem to matter if the time between the shots is one minute or one day, the velocity is weak for the shots from the middle range of the cartridge. Could the hammer spring be weak?


    Rob K

      • BB,

        I used a drop of pellgun oil on the co2 cartridge so I think the striker is lubricated.

        I had another muzzle plug from a 2620 and used that on the 2600 and now the gun fires powerfully from start to finish. That seems to have corrected the problem.
        I was then going to use the muzzle plug from the 2600 on the 2620 to see if that might be the problem.
        The only other thing I noticed was that the o-ring on the muzzle plug swells so much it cannot be put on the gun for several hours when it has shrunk down again.

        • Rob,,

          Pellgunoil will get on every surface inside the valve. The striker is outside the valve and will not get any of that oil.

          A swollen o-ring means the o-ring material is wrong. Someone has been replaced the o-ring with hardware store parts that aren’t right.


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