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Does size matter?

CO2 capsule lineup
Common small CO2 capsules. Left to right — 8 gram, 12 gram, 16-gram and 20 gram.

This report covers:

  • 1930s
  • I940s
  • 1950s
  • Advancement gap!
  • Your thoughts?

Airgunners think they have cornered the market on CO2 cartridges, but actually the world doesn’t know we even exist. Today I want to discuss CO2 cartridges and where we’ve come from, plus a little on where we have yet to go. I would tell you that the Crosman Fortify inspired this report, but the truth is, you readers inspired it. I almost couldn’t get Part 3 of the Fortify report out fast enough because you were all talking about CO2 guns.

The picture above says a lot, but it doesn’t say it all. The next one says more.

CO2 truck
CO2 transport truck.

That truck transports CO2 from the manufacturer to locations where the gas is dispensed. It holds a lot more CO2 than a 12-gram capsule. But if this truck’s output were somehow connected to a Crosman Fortify pistol, the velocity would remain the same. The pistol would get a lot more shots (no kidding!) but no change in power. And the point? The amount of CO2 only affects the number of shots — not the power of the gun! That said, let’s look at some CO2 gun history.


CO2 use in guns dates back to the 1870s with the Giffard guns. But the first practical use of the gas was in the 1930s when Crosman tethered their model 117 repeating pellet rifles to large CO2 tanks so the rifles could be used in shooting galleries.


After World War II Crosman bought up many (tens of thousands?) 4-ounce (113.4-grams) CO2 tanks that were used to inflate large life rafts. They modified their multi-pump rifle to use the gas and attached a tank to the bottom of the action, giving hundreds of shots

Crosman CG rifle
Crosman model 101 CG (compressed gas) rifle. That tank held 4 ounces 

This was viewed as an advance, since the rifle was no longer tethered to the gas supply. While shooters found it advantageous, shooting gallery operators found it dangerous because the rifles could now be fired in any direction.


In 1952 Crosman also converted their tethered model 117 rifle to the model 118 that was filled from a separate 10-ounce CO2 tank. Like the 101 CG rifle this one also freed the rifle from the tether, plus it didn’t have the large tank hanging below the receiver. But they weren’t alone. The Benjamin Air Rifle Company that was a separate company at that time also brought their model 250 CO2 pistol out in 1952. That one used an 8-gram soda siphon CO2 cartridge, making it free from tethers and also from bulk tanks. And the airgun race into CO2 cartridges was on!

8-gram cartridge
The 8-gram soda siphon cartridge was the first CO2 cartridge on the market.

In 1956 Crosman brought out their model 150 CO2 pistol. It was a landmark advance because it held a 12-gram cartridge that has 50 percent more gas than the one with 8 grams. And by the way, though the Blue Book of Airguns says the cartridge has a 12.5-gram capacity, it’s really just 12 grams.

12-gram cartridge
The 12-gram CO2 cartridge came to market with the Crosman 150.

Advancement gap!

From 1956 until the  2004 the 12-gram cartridge was the most popular cartridge for airguns with the 8-gram still being offered but in models that were not as well-known. Then in 2004 Crosman brought out several AirSource models that used 88-gram cartridges. That kicked off another round of airgun creations that we are still seeing. But between 12-grams and 88-grams there has been no activity. That leaves a gap that hasn’t been explored yet but could be.

While the 12-gram cartridge is probably the best for handguns, is it also best for rifles? Has anything been done to investigate this large middle-ground?

88-gram cartridge
This Air Venturi cartridge holds 90 grams but the threads on the neck allow for a small variation in the capacity.

If you look at the two larger cartridges at the top of this report (16 gram and 20 gram) you’ll see that they could be used in at least some airguns. Perhaps not air pistols but certainly some air rifles could hold them, and they offer much more capacity. That means more shots.

There are even larger cartridges that lie between the 20 and 88-gram size, so clever airgun designers need to at least consider them. Who knows, maybe they already have and didn’t find anything worthwhile. All I’m saying is that on the consumer side, we aren’t aware of anything that’s been tried. This gives us food for thought.

Some of you readers may be ahead of me on this. For example, bicycle riders probably know about the tire inflators that use 16-gram cartridges. Homeowners may be aware of the Gallo flush system for air conditioning drain lines that take the 20 gram cartridges. So, it’s not like these things are hidden.

Stock up on Air Gun Ammo

Your thoughts?

What do you think? Is the cartridge size gap an area that needs to be explored by airgun developers. If so — why? And if not, why not?

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.

108 thoughts on “Does size matter?”

  1. BB,
    Great info here; I knew about the 8, 12, and 88-gram CO2 cartridges; yet I had no idea about the 16-gram or the 20-gram ones…I learn new stuff here all the time…very cool. 😉
    Blessings to you,

  2. Tom,

    Commercially I cannot think of a reason to fill in the gap between the 20 and the 88/90 gram CO2 cylinder. Hammerli used to sell (maybe they still do) the Hammerli 850 that was powered by the 88 gram cylinder. There are more than enough shots inside a 12 gram cylinder before requiring reloading the rifle. Anything bulkier you pay the price of the rifle being heavier than it needs to be. The best niche of the CO2 cartridge lies in look alike pistols where you definitely do not need a bigger cartridge.


  3. B.B.,

    Size does matter!
    It may not matter for the first few shots but if the liquid CO2 is made to switch state to gas too rapidly it will lower the temperature of the liquid as well as the containment vessel and eventually the shooting devices valve/barrel as well. With a larger cylinder the cooling process is slowed down by an amount based on MASS of the contained CO2 as well as the surface area of the containment vessel.
    Gaseous CO2 can be liquefied under pressure provided its temperature is below 31 °C (87,8 °F), this temperature being referred to as the CRITICAL POINT. If compressed and cooled below the critical point, a colourless fluid, approximately the same density as water, is produced.
    CO2 will remain in the liquid form as long as its temperature remains below the critical point but will return to the gaseous state if its temperature rises above this point, regardless of the pressure applied.
    There are formulas and hodographs that explain it all if someone is interested in the exact amounts.
    Start here: https://www.eng-tips.com/viewthread.cfm?qid=240434


  4. Nah, I don’t see a gap between the 12g and 88g, as guns that may play in that gap can be designed to take multiple 12g cylinders or an adaptor that takes multiple cylinders. Some design that better (eg, Beeman QB78) and others not so well (Diana Trailscout with their iffy o-ring seal on the CO2 chamber plug). That area could use work, a little engineering to keep the CO2 pressure even more constant (eg, an upright tilting cylinder, a CO2 cylinder heater or at least a “cold radiator”), and good seals so one can keep the cylinder(s) loaded indefinitely.

    Shootski, I use “Magic Heat” pads, the kind that you click a metal bit inside and some chemical precipitates in the pad to warm it up (it can be boiled later to regenerate). I stuff one or two in a sock covering the CO2 paintball tank on my Condor if I’ll be shooting for a bit. They keep the tank warm on a cool day. Keeps my cheek warm too.


    • Mike, glad you chimed in here. Been thinking about you back to your comments on pumps and the bicycle pump you use(d)? I wanted to remark that I had given up on manual pumps (have two) and use CO2 cartridges to fill my bicycle tires when I get a flat. One 12 gram cartridge does the trick. For my motorcycles, tubeless at least, I now use 16 gram cartridges (3 to 4 to fill) because I couldn’t find a 12 gram dispenser. The dispensers seem to run from $14 up to $30 and 16 gram cartridges about $2.50 per. Still, beats waiting for a tow truck or walking. Just plug the hole in the tire and fill.

      The other day, I happened upon a sale at Harbor Freight for a battery powered pump for $10. One flat and it will equal the outlay for 3 CO2 cartridges and the dispenser! Hopefully it will last for one fill.

      Fred formerly of the Peeples Demokratik Republik of NJ now happily in GA which is definitely south of the Mason Dixon line!

  5. I could see “in between” cylinders useful for full-auto guns. As for the rest, no. 30ish shots out of my Sheridan (rebrand 2260) is enough. You can get 70 decent and 2 lousy shots out of a 1077. Do we really need more shots than a 12-gram provides for those guns? No; after all, can’t buy an 88-gram 1077 anymore.

  6. Not being into CO2, this is indeed a subject I have very little experience in. I have played with it before with a Crosman bb/pellet revolver/semiauto pistol a while back and I still have a 2240 I pull out on occasion, but the truth is I am underwhelmed.

    More than half of my shooting season it is a little too chilly for me to effectively use CO2 as a propellant. The capsules also cost a considerable bit. I have a hand pump, an air compressor and a carbon fiber tank to fill my PCPs and I have a fair collection of sproingers with the odd SSP and multi-pump thrown in.

    I have entertained the thought of a bulk fill CO2 airgun, but unless the right one comes along, that is not likely going to happen.

    As is mentioned above, there are CO2 airguns that use multiple 12 gram capsules. I have seen after market valves that are available for the 88 gram capsules. Now that is intriguing to me. That combined with a top shelf airgun just might get my attention.

    Advancement gap!
    All I’m saying is that on the consumer side, we aren’t aware of anything that(’s has) been tried. (delete the ‘s or has)

  7. Speaking of sproingers, that airgun company in the SW that deals in almost exclusively high priced airguns finally has the BSA Meteor Super at a reasonable price. I guess they could not sell them at what they were asking.

  8. I would like to see better management and options for use of the CO2 in the airgun. The current cartridge sizes are fine with me.
    Dump the CO2 into a cavity inside the airgun to avoid the rapid cool down with use, and offer an adjustable hammer spring for optional power levels.
    The Healthways Plainsman is a perfect example of a high capacity, variable power, repeating BB pistol that does not rapidly cool down and lose power under rapid fire like those that take CO2 directly out of the cartridge as needed through the small puncture hole.

    • Bob, so you are theorizing that the cooling effect comes from the CO² escaping from the pierced capsule, and doesn’t happen from a bulk filled CO² reservoir? I thought that the cooling effect occurred just from the conversion if the liquid CO² to a gas. So every time you take a shot, some gas is allowed to escape, lowers the pressure in the reservoir, which allows some liquid CO² to change to gas until the pressure builds back up to stop the conversion. Doesn’t that change from liquid to gas cause the cooling effect? I thought that is why folks put their bulk fill guns in the freezer, to lessen the amount of liquid flashing to gas when it touches the warm sides of the reservoir so they get more liquid CO² on each fill.

      The gun you describe sounds like the vintage Crosman 111, 112, 115, 116 pistols and the similar 113 and 114 rifles (I hope I have those model numbers correct) that were all bulk-filled from a larger CO² tank. You may also find a CO² gun that can be converted to bulk fill by simply replacing the piercing cap with a foster fitting. You can search B.B.’s prior posts about bulk fill.

      • Me thinks that I will be investigating all of this in the near future as I will likely have a bulk fill CO2 air rifle soon. Likely you are more correct than Bob M. He is probably “dumping” a 12 gram cartridge into a larger reservoir which is allowing the CO2 to become a gas before it is used.

        Sorry folks, I am “speaking” out of total ignorance as I have had very little experience with CO2 and have no experience at all with a Plainsman.

        • If you just put gas in, it will run out of shots rather quickly I would guess, because there would be no liquid CO² to keep the pressure up.

          I am looking into this too because I want to play with my Crosman 111 and 112 before I make the decision to sell them or not.

        • RR, I have three rifles based on the QB series. Two are in the “target” series, a thumb hole stocked .22 , a side lever cocking .177 and a standard model .177. I modified the piercing caps so they could use bulk fill or powerlets. I built a bulk fill “tree” with a gauge and bleeder to fit the bigger paintball tanks and the fun began. Twelve years down the road and bulk fill being harder to source I am back to using powerlets when I do shoot the QB’s but that is rare because I now am a convert to PCP rifles which are so much more convenient than bulk fill C02. You can purchase and fill tanks at restaurant supply and welding supply stores but I choose not to.

      • Roman,
        Yes, Co2 absorbs heat from its surroundings, as it transitions from liquid to gas turning things cold, but like the expansion valve in an air-conditioning system if the rate of expansion into a gas can be controlled you can increase or decrease the rate of temperature change. Dumping the CO2 into a larger cavity provides more area for the CO2 to absorb heat from and slows down the rate of expansion by having more CO2 available to convert to gas and build up pressure. The best I can make of it.

  9. For so long I was beyond the CO2 capsules topic at all. Now the time came for me to discover a great area of replicas, BB’s and general plinking-for-fun stuff. After years of shooting springers I made first steps to the dark side (first PCA and then PCP) to discover this new way of airgunning. The last two years actually – my step into CO2 powered systems. First I had CP99 compact with blow back, first time shooting BB at all. At the moment I have really much fun with Umarex Legends S25, Makarov, Winchester (cowboy rifle). Experience only with 12g capsules so far. I learned so far how it is to shot at cold ambient and how it is to miscalculate how much 12g capsules and BB’s you need for a vacation with pilnking. 🙂
    What I think is 12g capsule makes sense, when it is too small you can expand to 2 capsule system (like UX cowboy rifle), but do you really need 88g big one? Perhaps, but not so often as this 12g standard. It is enough to have some fun, it is small to fit pistol design, it is easy to handle.

    Now the most important thing: 12g CO2 capsules are cheap! You can buy a lot of them and don’t have to worry about supply. If I can get like 30 – 40 shots (or more) from one capsule – I’m fine with it. S25 revolver will get you to 70 shots+ with one capsule. 100 shots in warm conditions is normal. That is a lot shooting!

    88g capsule delivers much more shot count but it has the biggest disadvantage compared to 12g capsule – it is relative expensive. It is also not so common (can’t buy everywhere). Not so easy to handle

    Everything counts in great amounts. I think the 12g capsue will stay for a long time as a prime power source for CO2 guns.

    • For economy plinking the 12g capsule is a winner. Buying on sale for $.40 each and getting at least 40 shots, at good velocity, per capsule equals cheap plinking with my replica revolvers, blowback pistols and Crosman 2300T. Using the Umarex 12g adapter instead of 88g tanks with my 850 M2 still saves a bit : 8ea 12g – $3.20 vs 1ea 90g – $8.33.

    • I bought the”Cowboy” smoothbore “rifle” four years ago. I immediately drilled and tapped the side plate in the standard Marlin/Winchester pattern and installed a Williams peep sight. So much fun. The .177 cartridges made for the Umarex pellet revolvers work and wadcutters shoot amazingly well in it. Last month mine developed a leak. Thus far I have not had the time nor courage to get into it. This design troubled me when I bought it, lots going on in it. I own lots of lever action rifles and used to shoot Silhouette with them so this was a natural analog for practice but the novelty soon wore off. Do not stand on Saint Augustine grass and eject the cases, very hard to find. I do plan to look into fixing the leak but not any time soon.

      • Singleshotcajun,

        It is amazinlgy accurate with pellets, also the revolver S25/40/60 cartridges work (bit more difficult to load). As usually I shot some soft blancket to catch the pellet and see how it deforms and fit the barrel, you can see the pellets are very well pushed through the barrel and it seems that the inner diameter is a bit smaller than 4.5mm. At 10m distance it is not very pellet picky! My wife tried it and she could hit every thing on my shooting gallery – great way to come down after hard day at work, she admitted.
        Most common leak is the seal on the 8A part (Umarex original schematic) – this green seal directly on the capsule screw. Each time you change to a new capsule you have to unscrew and screw it tight again. Always use some silicone oil on it – after few hundret times it might get damaged.
        If the leak is not there you may try to put few drops silicon oil directly into the transfer port, where the CO2 is hiting the pellet (or BB) in the back of the cartridge – and let the gun stay for some time straight up (barrel up), then shot few times dry without CO2 to let the oil go through the valve O rings inside it. Here there is not directly possible to just put some oil on the CO2 capsule to force the oil to go throught the valve – because of the capsule loading compartment design.

        • The leak is in the receiver. I watched a you tube video on sealing the “Cowboy” rifle of which there is very little info and fewer parts to be found. I believe the leak is an o-ring where the brass tube goes into the power valve. I will try a silicone IV via full cartridge and manually pressing in on the poppet.

  10. I have wondered about the possibilities of more sophisticated CO2 guns. The PCP guns have gauges, adjustable regulators, adjustable hammer springs, etc. Would any of those types of items make sense for CO2 guns? Sometimes basic simple guns are all we need. But other times the bells and whistles offer some advantages such as adjustable power, more consistent velocity, more shots, knowing how much gas remains, etc. Has anyone explored this idea?

    • Elmer,

      At the beginning my advanture with CO2 powerplant I asked the same question. Now I think it would have happen if it would be a real concern. Most of the CO2 powered stuff is plinkers. There is no need to now all the details, it has to work relative stable and be easy to handle.
      Some of the match guns were driven with CO2 – which was not used for a long time. These were really sophisticated and had solutions similar to PCP.

      The big difference is also the pressure. You get depending on ambient temperature pretty constant pressure from the CO2. You will get like 50 – 75 bar pressure, usually in this range, out of it. There is no need to use regulator for this – compared to 200bar or 300bar PCP max pressure value. So alone based on the narrow pressure range you will get out from this “power cell” there is not much to do.

      What would be nice is some cavity filled with gas CO2 to avoid liquid coming up to valve etc. which causes velocity differences. Also to avoid lowering the system temperature rapidly, especially during fast shooting. This causes design issues and usually cost some shot count.

        • EF,

          As tomek and RG state, CO2 is self regulating. The problem I have with CO2 is with the ambient temperature and the low pressure. I cannot use CO2 in the winter around here and the lower pressure limits my ability to shoot long ranges.

          Another thing I have a problem with is many CO2 guns will not stand up to what I will put them through. Most are cheap bb plinkers. There are very few high quality CO2 powered airguns made anymore.

          Mike Reames is someone who makes big bore CO2. He makes CO2 pistols and CO2 rifles that are most definitely top shelf. I often see him and his wife at airgun shows. He often has a table or two of his various models for sale at these shows.

    • Because of the relatively constant pressure of liquid CO² under pressure, it is self-regulating. The way you know how many shots you have left is knowing your gun and filling consistently, then counting shots. The other way is to weigh the gun. Liquid CO² has mass that can be weighed on a simple digital kitchen scale.

      • Thanks, that makes good sense. And it works well for shooting targets in the basement. Shoot 10-shot groups and keeping track of the number of shots is relatively easy. Don’t need any more power. And the temperature isn’t too cold.

    • Yes, tinybobh, I do remember those engines! They’re still used in lightweight free-flight model airplanes. I still keep one up as an item of visual of interest in my shop, mounted on its very crude test stand. I think this one was made in Czechoslovakia.
      The tiny tank in the stand is filled from the 8-gram bottles, using the black fixture that has a ball bearing valve at the top. The coils of brass tubing between the tank and the engine assists in heating the CO2 to a gas before it arrives at the top of the cylinder.
      Do you see that tiny white piston standing on the base? That fits this engine. While at the top of the stroke, the pin at the top of the piston pushes against a ball bearing valve in the cylinder head, This admits a puff of CO2 into the cylinder that pushes the piston down for one rotation cycle. The CO2 exhausts through ports in the cylinder near the bottom of the stroke, like a regular 2-cycle engine. Momentum in the system keeps the crankshaft turning and the piston comes up for another puff of fresh CO2, and the beat goes on. They can be tuned for power or efficiency by moving the head valve up or down. Very fun.

  11. Anyone have experience of these refillable 12g cartridges?

    Seemingly they can be filled to 200bar with a hand pump, turning CO2 pistols into PCPs.

    I’m curious to hear if they work and if so, how the shot count compares to single-use 12g CO2 cartridges

    • Bob,

      Do you know the LEP system? It is based on this principle, especially in revolver system. You have cartdrige which you can pump up to 300bar and there is the pellet above, just like a standard firearm but with compressed air. This is only for one shot – but similar.

      12g liquid CO2 will give you approx 6,1 liter gas (am I right? 1mol = 22,4dm^3, 1 mol CO2 weights 44,1g). This is what you have in the pressure range 50 – 75 bar usually, depending on the temperature.

      Let’s make it simple and calculate with 12ml volume compressed air, which will give 3,6 liter air compressed inside capsule (300bar). There would be the issue with consistency. My stormrider (all 200bar max) with 100ml tank volume will give you in .177 cal like 80 good shots in 5FPE range. Same story 36FPE 5 good shots in .22 cal, max 7 good shots at max energy. Diana Bandit .22cal give 7 shots in range 15,8FPE from 50ml volume @200bar.

      I think even with 300bar this 12ml is too small (maybe it is more volume in the capsule, but not much more as usually you will fill liquid CO2 like up to 85% of the available volume) to make it reasonable for multishot tank.

      Quick edit- let me please fill one empty capsule with water to see the volume inside! I will do it in a few minutes.

  12. All right guys! I checked the empty 12g CO2 capsule from Umarex which I shot yesterday from my cowboy rifle.
    I used needle and syringe to do this properly. And – approx 14ml water entered the capsule. This fit to the theory very well!

    Liquid CO2 will give you relative huge volume of gas CO2, unfortunately the Max pressure will not be high like a PCP. You get something like an PCP regulated output out of it.

  13. Ah the world of CO2, I delved into that world above the Critical Pressure/Temperature for many years trying to design a power generating plant sized to fit on a submarine to replace the current steam system. This is a very compact but dense system. Meaning the submarine would have more internal volume than the volume merely to contain the system. The submarine must be able to submerge and surface.

    The problem with any polymeric seals CO2 tends to destroy them over time. Some polymers last longer than others but all will absorb CO2 and slowly leak. I’ts only a question of how much leakage is tolerable for the system. For a system on a submarine any leakage is too much leakage and the mechanical joints would be sealed with a metal o-ring, imagine a hollow thin walled torus tube, similar to an o-ring only hollow and made of metal. Single use only, disassembly would require a new seal.

    Could a CO2 system be designed to operate an air rifle? Essentially everything required is available. However, the specific sizes of each component in the power plant would need to be optimized for the muzzle energy desired. A heating system could be added to control the plenum pressure / temperature to allow for a higher input pressure to the firing valve and hence change the muzzle energy / velocity.
    Safety systems are easily added to control the maximum pressure / temperature, but no doubt someone would bypass the safety controls and injure / kill themselves or others.

    This would be a very complicated system only remotely resembling the original CO2 power plant. Could it be made? No doubt, yes. Would it be commercially viable? My opinion, doubtful.

  14. BB

    In between sized CO2 cartridges makes sense for full auto BB guns. Not so much for others unless seals/valves can handle the storing of partially used CO2 cartridges without leakage or getting stuck. This does seem doable since those that use back to back 12 gr cartridges are capable of doing that. Both my Crosman 160 and Beeman AR2078A have no problem holding partially consumed CO2 cartridges. I have too many different airguns that want to be shot to devote an entire day to only one gun. See below.

    I have mentioned this before here but will say it again. For whatever reason my Beeman AR2078A gets nearly 100 good shots on the two back to back cartridges. This is about double the advertised number. This rifle left the factory tuned to do this. Whether this was deliberate or by chance I have no clue. Since replacing the original barrel it delivers sub 1” accuracy at 25 yards. Temperatures where I live allow outside shooting about 8 months yearly so CO2 guns are practical for me. This rifle always has a partially used set of cartridges inside along with a note stating the number of pellets shot.

    Good report and so informative. Thanks for what you do.


      • hihihi

        Accuracy at 25 yds with rifles rested is very similar for 10 shot groups. The 160 has the rear peep sight and the Beeman currently wears a 20x scope. Groups for both generally range from 1/2” to just under 1”. The Crosman 160 is the loudest air rifle I own. Pellets for the .22 are FTT and AA Express for the .177.


    • That the Crosman 160 is exceptionally loud is disappointing. I just bought one to refurbish. When you get a chance, I’m very interested in the velocity you are getting out of your AR2078A. I have one and the seals gave out just after the warranty period expired. When I reseal it, I am interested to know what makes yours tick.

      • Roamin

        See my reply to Remarq above about chrony comparisons and pellet weights, etc.

        The Crosman 160 is a joy to shoot but it gets only a few shots in my rotation due to noise. I don’t want to get some new neighbor bent out of shape about somebody shooting guns nearby.

        As for why my AR2078A gets so many shots on two CO2 cartridges I’m guessing the hammer spring left the factory with less spring tension than normal.


    • alongship,

      And here is what you missed:

      “Anyone have experience of these refillable 12g cartridges?

      Seemingly they can be filled to 200bar with a hand pump, turning CO2 pistols into PCPs.

      I’m curious to hear if they work and if so, how the shot count compares to single-use 12g CO2 cartridges”

      “Anyone have experience of these refillable 12g cartridges?

      Seemingly they can be filled to 200bar with a hand pump, turning CO2 pistols into PCPs.

      I’m curious to hear if they work and if so, how the shot count compares to single-use 12g CO2 cartridges”


      Yeah, I have experience. The one I bought didn’t work at all. It was the parts of a science experiment.



    • I think I have seen where folks convert their CO² guns from using 12g cartridges to bulk fill, and then adapt sodastream bottles, paintball tanks, or fire extinguishers as their bulk-fill CO² source.

  15. I don’t remember if this concept was tested, but I remember guys speculating about adding a small amount of CO2 into the chamber of a springer. The idea that the compression in the chamber would energize the CO2 to higher pressures and increase the power of a springer. This is a similar but different thought as the idea behind the HW35 Barracuda.

    David Enoch

      • Love my Frugal Caldwell. My AR 2078B shoots around 550 FPS with Meisters or Crosman Wadcutters and is far more accurate than I can shoot ,no problem hitting airgun pigs Offhand at 20 yards with the factory sights.

          • I get about fifty good shots before it starts shooting low. I know at some point I did a number of shots before significant fall off occurred test but I can’t remember. I shot it bulk fill for so many years and I would just top off after fifty shots. These days I don’t count shots and will bleed down when shots fall off then change cartridges. The AR series has a bleed off feature which is nice.

        • I rarely use my Caldwell. I could not see spending $500 for something I do not use very often.

          I had thought about those Chinese CO2 rifles, but decided they were not for me.

          • I cannot speak to the Beeman rifles as all of mine are pre Beeman. I am really tempted to get a Beeman AR2079 with the 190cc 850 psi regulated bottle, just shy 200.00 for a pcp “target” rifle. QB’s are really easy to reseal and tune, only the poppets are getting hard to source. Next time I need a poppet I will try Mountain air for a Delrin one.

              • Thanks, I bought my last two poppets from Archer , He has the factory poppets . Next time , I think I want to go with Delrin or Teflon. Last year I bought an AR series trigger from Archer for my standard QB, really like that trigger. Now all three of my QB’s have the same trigger.

                • I understand. I do find it somewhat surprising that they are wearing out so much. I think I would try the Teflon first as if I am recalling correctly, it is somewhat self lubricating. I am not very familiar with Delrin, with the exception of it is very tough. I guess you could try them both and see which is more suitable.

                  BTW. I like your “nom de plume”. Until this past NC Airgun Show where I bought an Armada, all of my airguns have been single shot. Fortunately, it has a single shot tray.

      • I waited patiently for a deal on the bay and got a Competition Electronics with the blue tooth module and the infrared lights for the basement shooting range for about $40. Right on!

        Now my Shooting Chrony Alpha with the incandescent light kit is the backup.

  16. BB,

    I recall someone replacing the bottle of a 1st gen Gauntlet with a CO2 container (88g?). As I recall, it just screwed into place and had a huge number of shots, at a someway reduced velocity.
    Did I remember correctly, or is my recollection wrong?


  17. And speaking of CO2 airguns,
    I replied in the Crosman Fortify Blog that I was easily able to fan it, but I did it at a slow pace so as not to abuse it and mentioned that it felt more powerful than most CO2 pistols. Well, I found one sale ad that claimed it could shoot bb’s at 420 fps. I did not check but I can certainly believe it.
    Today I received an ad for a new Barra 1858 CO2 Cowboy Pistol that appears to be a takeoff of the Fortify and claim it will shoot at 400 fps. It has an octagon barrel, same fixed cylinder but with imitation wood grips.
    There is also a gold two tone version. They say it is light weight but well balanced, could say the same for the Fortify now that I think of it. Hope it turns out to be just as realistic looking… well for a synthetic plinker without a rotating cylinder. Just ordered one.

  18. Speaking of CO² cartridge history, I just bought an old Crosman Model 70. It is modeled after the Winchester Model 70 centerfire rifle. I opened the compartment where the CO² cartridge is stored, and guess what I found?

  19. Gentlemen, ladies, to whom it may apply – a Blessed Veteran’s Day to all you who served so we are able to honor you today, in peace and with security. Hope and pray both endure in our Republic. “A Republic, if you can keep it.” -B. Franklin

    • 100% agree! Our kids at church just did a service project for our local veterans last night. We must all be thankful for their service and sacrifice, and that of their families who often bear the brunt of it.

  20. B.B. and Serving and Veteran Readership,

    Happy Veterans Day!


    PS: For the rest of you this is a day to CELEBRATE their families and their sacrifices!

    Peace unfortunately at the current level of Human evolution is only maintained by Armed and Eternal Vigilance.

  21. Veterans Day.
    Not really a day of celebration, but more of respect for those who sacrificed for our country. There are things veterans give up for the rest of their lives that many who never served never even consider. In addition to any war injuries they may have suffered.
    Being in the service for 20 years, I have totally lost track of 10 cousins and half the friends I grew up with. And then there are the many friendships you develop at various duty stations. People never to be seen again.

    You are basically excommunicated from most family and relative events while serving. Now I’m talking about the time before the internet when making a long-distance phone call from overseas cost a small fortune. Aside from boot camp, where you can’t really leave unless there is an emergency. I was never less than about a thousand miles from home. And that does not include overseas assignments.

    You basically give up your life and must adapt to an ever-changing lifestyle and location every few years and it is very detrimental to your immediate family, if you are married with children, for the same reasons. They give up their friends and life.

    The early retirement compensation helps to try and compensate for it all, but it can never replace what you have missed out on or opportunities that may have passed you by.

    Your sacrifice begins the day you enlist. In times of war and peace. For the most part, the military operates as if it’s always in a state of war being prepared for anything through deployments, training and exercises.

    Knowing that you have joined a brotherhood of those who have served and sacrificed for their country remains a source of pride for the rest of your life.

  22. Quote BB
    “That truck transports CO2 from the manufacturer to locations where the gas is dispensed. It holds a lot more CO2 than a 12-gram capsule. But if this truck’s output were somehow connected to a Crosman Fortify pistol, the velocity would remain the same. The pistol would get a lot more shots (no kidding!) but no change in power.”

    A lot more shots, indeed, could a person live long enough to empty that co2 container using the Crosman Fortify pistol, I think not.


  23. Something to consider as this Veterans Day come to an end.

    Evidently a survey was conducted, and they found that a majority of Vets feel a little uncomfortable when someone says, “Thank you for your service”.
    Some Veterans may not be happy about what they have accomplished in a war zone.

    They may feel obligated to respond but not sure what to say. “You’re welcome” doesn’t quite fit. You really did not do it for that person, and it simply turns out to be an awkward situation of exchanging canned greetings.

    “We will never forget what’s been done for us.” cut down to, “Never forget” can be the Serviceman’s reply as well, having acknowledged you caring about his service to our country.

    Other than that, engaging in conversation about his service gives him the opportunity to discuss a noteworthy experience. Something he may be particularly proud of… “Never Forget!”.

    • One more thing,
      Some Servicemen may feel that their service was all in vain, as a result of an unfavorable outcome for all the traumatic experience they went through. “Never Forget” has no positive or negative connotation, and it implies that the greeter also believes that it was not in vain. You did your part, and they appreciate it.

      • As an ex-Navy dude, I have heard “Thank you for your service” many, many times. My usual response is a slight smile and a nod, sometimes followed by a “Thank you”. They do not know, but should be acknowledged and thanked even though the statement may seem “canned” to some, it may be heartfelt by them.

        The very thought of hearing “Never Forget” brings tears to my eyes. No, I will “Never Forget” what I and others have been through for this Nation. Thankfully, most do not understand.

  24. This feels awkward and yet, I now have to say:
    Not everyone feels good and proud and/ or grateful about any kind of military, whether past, present or future…

    I respect your thoughts and sentiments but, personally, I can not accept them.

    • Some may disapprove of what you say, hihihi. One thing is true – military men and women have defended to the death your right to say it. For that and many other reasons, FM honors them.

    • hihihi,

      Don’t feel awkward!
      But please try to understand my repeated main comment from above:

      unfortunately at the current level of Human evolution is only maintained by Armed and Eternal Vigilance.

      Perhaps someday we will both find ourselves with nothing to debate or disagree about on this topic.

      From what i see happening around the planet just now i have little hope that day will be soon. Sadly!


  25. Further thoughts. Perhaps the airgun industry could further explore more intermediate size CO2 capsules. Because the gas is “self regulating”, the 16 gram threaded capsule would be an excellent choice for use on a target pistol. For a brief period of time they did do such, though they were bulk filled if I am not mistaken. Mike Reames has made a plethora of CO2 powered pistols and rifles similar to the ones that used to exist.

    For this to happen, the industry must think outside the box and bring out pistols and rifles that are CO2 powered, but are not replicas of firearms. They did so at one time, but with the advent of PCP, CO2 fell to the wayside. It is still used in the replica world and where low power and/or velocity is desired, such as in paintball, but overall most people prefer the price savings and/or convenience of PCP or sproingers. Face it, the cost of CO2 capsules can add up fast. Bulk fill CAN be much cheaper, but it is very inconvenient for most.

    Something else that should be considered is that CO2 supplies will likely be outlawed in the USA in the future as it is one of those nasty “greenhouse gases”. OOOHHH NOOOOO! You folks who are into the replica world are destroying our “Mother Earth”! (insert satirical sneer here)

    P.S. for BB
    Your thoughts?
    What do you think? Is the cartridge size gap an(d) area that needs to be explored by airgun developers.

    • RR,

      I agree with those who have said the makers of full-auto BB guns should experiment with the larger cartridges.

      The problem is, it becomes another size cartridge that isn’t standard in the airgun world. That is solved by using a cartridge that is extremely common elsewhere — the 16-gram bicycle tire inflator and the 20-gram air conditioner drain line flushing cartridge are two to consider.


      • BB,

        I myself am not into the full auto bb guns, though I have played with them very briefly. My thoughts were for the 16 gram screw in for target and plinkers. Only the replica crowd needs their plinkers to look like real firearms. I have a 2240. I would not mind if my plinker looked more like it than the latest and greatest firearm. I wished they looked more like something from Star Wars or Star Trek.

  26. B.B.,
    Although they are common sizes:
    the 16-gram bicycle tire inflator and the 20-gram
    there are far more common ones!
    PFD (Personal Floatation Device) aka, inflatable Life Jacket REARMING KITS come in CO2 Kit: 20, 24/25, 38, 65, 88, and 95 Gram Cylinder Cartridges; i’m certain there are other sizes in unthreaded as well as threaded.
    Life Jackets require inflation assembly replacement/testing on a regular schedule. Just like Signal Flares they have EXPIRATION DATES that are non negotiable.


    16g – 22ml H2O capacity

    25g – 34ml H2O capacity

    38g – 62ml H2O capacity

    65g – 98ml H2O capacity

    88g – 97ml H2O capacity

    95g – don’t know, a lot

    Simple if the airgun designers give even a modicum of effort at online research….


      • Roamin Greco,

        see my reply to edlee.
        I have a number of CO2 guns some run on 12gram but most are bulk fill from a 20lb cylinder. I bought it at least three decades ago…it has been refilled (in the first decade of ownership) maybe three times. I think it is in need of a 5 year hydro check!!!
        Hpa just took over to run most all the guns i shoot regularly. Luckily i have a great Dive Shop just minutes away that fills my 100 cu.ft. CF cylinders to an actual 4,500psi from their fill system of cool/dry/breathable air for US $7.00 per and do it in minutes while i wait.
        i need no expensive compressor and the cost and headaches that brings. Lucky that i truly know!


    • I know from reading this blog and other places that many CO² pistols and rifles are convertible to bulk fill. But folks may not want to bring along a heavy CO² tank on a short trip away from home base. These larger CO² capsules with a valve may give one two or three or more fills in a convenient size that is easier to carry around than a tank. Very interesting.

      • Roamin Greco,

        Many folks used to use the big tank to refill the small(er) cylinders once they had the on/off valves and the proper fittings. The paintball world used to be the place us airgun folks got most of our bits and pieces.
        I remember coillies with slide shut off valves connected to 7.5, 12, and 20oz Catalina aluminum cylinders in backpacks were big for a time.


  27. BB

    I have read all of the above comments and still I don’t have enough knowledge to understand the more technical aspects.

    I am curious. The Girandoni rifle operated on a pressure of 800 psi or less. CO2 can produce that amount, weather permitting. So, is it possible to build a similar rifle, using CO2 as the propellant and reach the same or similar velocities and power?

    My guess would be that if it could be done, someone would already be doing it. But a weapon with a range of over 125 yds and powerful enough to kill at that range seems attractive on many levels.

    I know that there are any number of PCPs that could fill that role. But just for curiosity’s sake, I was wondering what has kept it from happening.


    (. Is the cartridge size gap (and,, should that be an?) area that needs to be explored by airgun developers”)

    • edlee,

      To fill in some blanks that Tom left:
      Direct from Quackenbush: https://quackenbushairguns.com/outlaws.html

      “The Brigand shoots a .375 lead ball, the size used in .36 cap and ball revolvers; the ball is made by Speer/Hornady or cast on your own. The Brigand is able to be charged with either CO2 or air (at 1400-1600 p.s.i.). CO2 power with an 84-grain lead ball is 600-650 f.p.s. and 67-80 ft.-lbs. The ball proved to be accurate because the barrel was made with a gain twist and choked muzzle.

      Operating on CO2 at about 60 ft.-lbs., you get 10-12 shots per fill. You can hunt any small game with certainty. Dispatch a feral dog without a second shot. Or at 40 yards make soda cans fly through the air. The big round ball really makes them move. Then, really impress your buddies-run the pressure on air. You can get over 800 f.p.s., which is 120 ft.-lbs. At this power level, you break standard targets and blast through plywood backstops. Be careful!”

      Notice how much more power is posible with even a relatively low air charge (1400-1600psi) because air molecules on average are so much smaller/less massive than CO2.
      BUT you do get way more shot count with CO2 from similar sized pressure vessels. If CO2 just wasn’t so sensitive to ambient and operating induced chilling it would be much more useful for certain applications.

      I have a few early modern era PCP airguns with Spool Valves that can operate on CO2, Helium, Nitrogen and just about any non-combustible gas you can think of.
      Helium is KING for maximum velocity but it leaks and leaks and leaks no matter what!

      I think the size to shot count and perhaps in warm/hot places semi or automatic (at slower cyclical) is about the only place CO2 makes a little sense until capacitor/battery technology eliminates even that small niche.


      • Shootski,, and BB if he is listening

        I appreciate the explanation. I knew that there were a few large caliber air rifles that could be used with CO2, but wasn’t sure about the “why nots”. Of course I was aware of the temperature disadvantage but was educationally disadvantaged about anything more.

        The more I think about it the easier it is to understand why CO2 isn’t popular, now,, but I had wondered why it wasn’t the earlier nineteen hundreds when high pressure air was not as easy to source.

        It would seem that the lower working pressure and larger shot count might have been more attractive. But today, high pressure air is as far away as your workbench or the trunk of your car, so any advantage CO2 may have had is gone. Add the very real fact that speed sells and the coffin is nailed shut.


  28. Pyramyd Air has the new Diana Trailscout with 3 CO2 cartridges rifle listed (out of stock). Does anyone know if its valve/seals allow partially used cartridges to be stored in the rifle?


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