Home Blog  
Education / Training Why not CO2?

Why not CO2?

This report covers:

  • Dropped 4 points
  • What good is it?
  • Regulation
  • More shots
  • Temperature limitations
  • Power limitations
  • So what?
  • CO2 yes or no?

I’m writing this report to balance the scales so all three powerplants receive exposure. It’s certainly not equal among the three — spring-piston, compressed air and CO2, but at least they are all addressed to some extent.

As airgunners you have probably picked your favorite one. And some of you like all three. Personally I like precharged when I’m working with them, multi-pump the same and the same for single strokes, then of course the same for springers. When I’m shooting CO2 I find that I like the other powerplants better. I am not a CO2 guy.

Look at today’s title carefully. It could be asking why don’t you try CO2, but just as easily you can drop the question mark and it can be telling you why CO2 isn’t good for you. I suppose that summarizes how I feel about the gas. Let me elaborate.

Dropped 4 points

When I was shooting in a sanctioned regional match with my Chameleon target pistol I was in the middle of the match when my pistol ran out of gas. I had been shooting 9s and 10s and the hold for the next shot was a perfect 10, but I heard the pellet go out and knew that the gas pressure had dropped drastically. Instead of a 10 I shot a 6. It was directly below the 10.

I was running my Chameleon target pistol on bulk CO2. There was no way to tell how much gas remained and it ran out in a match, causing me to drop 4 points. 

10-meter pistol target
Instead of 10 points the Chameleon’s gas ran out and the pellet hit the six ring, directly below.

That shot took the wind out of my sails and I started flubbing my shots. What should have been my first Expert match score (545/600) dropped to a low Sharpshooter score (521/600) and ended my time as a pistol shooter. On the drive home my Chrysler Town and Country minivan blew its transmission from a flawed nylon gear that the manufacturer knew about and my day/week/month was gone. If I had been more determined, this experience would have strengthened me and I might have gone on to national-level competition. But instead I became an also-ran.

Am I blaming CO2 for my failure? Yes and no. Yes for the loss of 4 points and no because I’m the one who quit. But I will say this — you don’t see CO2 pistols or rifles on the medal stands at the World Cup and Olympic level that often.

What good is it?

If CO2 can run out at inopportune times, as I have just related, what good is it? Why do we use it at all? Here are some reasons.


Everybody knows that a pressure regulator is a good thing for an airgun. We want them in our precharged pneumatics (PCP). Well, with CO2 the gas gives you pressure regulation. Here’s how. When you charge a bulk CO2 tank, such as the one on my Giffard rifle, or use a CO2 cartridge such as the ones I reported on in That little silver bottle, as long as liquid carbon dioxide remains inside the tank, the pressure remains constant, within a range of pressures that depend on the temperature. That means the velocity remains constant, as well.

What happens is some of the liquid evaporates to gas as the gas pressure decreases. A shot decreases that pressure and more liquid evaporates to take its place. At 70 degrees Fahrenheit, which is 21.11 degrees Celsius, the vapor pressure of CO2 is 854 psi. That means that on a 70 degree day, your airgun shoots with about 850 psi. If you had a way to make the volume of your gas supply smaller the pressure would not increase. It would simply change more of the gas back into to a liquid. CO2 is a self-regulating gas, and because it is, a 500-gallon tank of liquid CO2 puts out gas at the same pressure as a 12-gram cartridge whose volume is tens of thousands of times smaller.

More shots

A direct benefit of the self-regulation I just described is that a small supply of liquid CO2, such as what’s found in a 12-gram cartridge, can supply power for many shots. The lookalike CO2 pistols that get 50 or 60 shots on one 12-gram cartridge are examples of this. Fill those same cartridges with high pressure air and you might get one-tenth that number of shots. When I pressurized the .375-caliber Quackenbush Brigand with air, the rifle went down from 30 shots on CO2 to perhaps five on air. That was a big bore rifle that had a large reservoir!

Stock Up on Shooting Gear

Temperature limitations

We know that as the ambient temperature rises, so does the pressure of CO2. If the pressure rises too far it overwhelms the firing valve and the airgun “locks up.” When Paul Capello first filmed the American Airgunner TV show, he didn’t know this and I recall a day when the guns we had set on a table in the sun for filming locked up and would not fire. Putting them in the shade for 45 minutes corrected the situation.

I gave you the pressure peak for 70 degrees F. At 100 degrees F the pressure is more than 10 times greater. This is why we don’t leave CO2 guns or tanks in a hot car. I know people who have had their car windsheld blown out when a small tank exploded. There is supposed to be a burst disk in each tank to prevent this but clever people find ways around that.

Also, as you shoot some guns are cooled by the expanding CO2 rapidly. This changes the velocity for the next shot. Some guns can lose 100 and even 150 f.p.s. when firing rapidly. Other guns are affected much less. This is a case when a chronograph comes in handy.

Power limitations

Carbon dioxide gas has limits. We know what the pressure limits are, but there are also limits to the length of the barrel. And that means there are limits to the velocity.

All airgun powerplants have velocity limits. Pneumatics top out around 1,600 f.p.s. Spring piston guns can just reach 1,500 f.p.s. and CO2 guns never reach past 900 f.p.s. These limits all have to do with the expansion velocity of the gasses involved. That’s why pneumatics and spring guns are so close — because both depend on the expension velocity of air. Run a PCP on helium and you can get it up over 1,800 f.p.s.

And here is where a knowledge of black powder comes in handy. Black powder also uses barrel length to develop velocity to a certain point, but after that limit is reached, there is no more velocity. Where that limit might be is the subject for much debate, but it’s somewhere below 2,500 f.p.s. Velocities of around 1,800 f.p.s. are quoted a lot.

So what?

The reason I’m telling you this is so you will be able to spot when people say things about CO2 guns that cannot be. For example, they tell you they have a .22 caliber CO2 rifle that develops 50 foot pounds. To develop 50 foot pounds in ANY caliber at 750 f.p.s.(being generous here) you need a projectile that weighs 40 grains. Do 40-grain pellets exist in .22 caliber? The JSB Beast weighs 34 grains, so it has to go 814 f.p.s. Can that be done? Theoretically. Just be careful that what they tell you doesn’t become your truth before you see the results. And, when they tell you they are doing it with a carbine that has a 14-inch barrel, walk away. That’s too much supposition.

CO2 yes or no?

What is it going to be for you? If you want a lot of shots without doing anything except perhaps reloading ammo, CO2 is a good choice. If you want a lot of power without being affected by temperature, maybe CO2 isn’t the way to go. If yoO2u have to know where you are as far as the fill goes, avoid CO2 or be prepared to waste some by replacing cartridges before you have to.

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.

46 thoughts on “Why not CO2?”

  1. BB,
    I find that CO2 guns have their place, or rather, two places:
    1) Guns like my vintage Crosman 357 give me good amount of double-action trigger time cheaply;
    (I get 50 good shots from a 12-gram cartridge before I replace it)
    2) Guns like my Umarex/NRA/Colt Peacemaker let me unleash my inner cowboy…just plain fun!
    (I get 48 good shots from cartridge; I could get a few more, but “8 cylinders full” is easy to remember)
    Fortunately, in middle Georgia, the cold weather season is pretty short.
    Also, I can shoot inside during the coldest months.
    Hence, CO2 guns do find a home here; they may not be powerful, but they are lots of fun. 🙂
    Blessings to you,
    P.S. If I’d have dropped a shot with one in competition, I’d likely be less fond of CO2 guns.
    But our mini-farm is not that big.
    The other day, I fired 6 shots with my .38 SPL derringer to pattern shot for snakes.
    My neighbor said she told her husband, “You think Dave is shooting at a snake?”
    Him: “Man, I hope not! Because if he is, he needs to learn to shoot better!”
    Technically, I could shoot a real .357 or .45 Colt here as much as I wish.
    However, if I did shoot such guns as often as I shoot their CO2 counterparts, I’d become…unpopular.
    I use big guns when I have to; and my neighbors know and appreciate that.
    Most of the time, I shoot airguns; no one hears them, so no one knows how often that is (it’s a lot).
    CO2 guns are a way to shoot firearm replica repeaters quietly and safely.
    Hence, for me, they have their place.

    • Dave,

      My neighbors probably wonder why it is so quiet in my chunk of woods. It is indeed a very rare day (or night) you do not hear shooting around these parts.

      • RidgeRunner, it’s the same around here; and since, like you, I don’t hunt anymore, things are pretty quiet in on my chunk of land; I shoot a bunch of those CCI Quiet rounds (that BB tested for us); my closest neighbor is 80 yards away, across the street ( truck driver who sleeps during the day), and he says he can’t hear them at all. 🙂

        • I think CCI quiet is the same as the old CCI CB Long. I still have a precious few boxes of CB longs. Out of my old long barreled Remington Targetmaster CB longs are Hollywood quiet but dispatches armadillos efficiently .

    • Dave,

      “If I’d have dropped a shot with one in competition, I’d likely be less fond of CO2 guns.”

      You got that right. Tom, understandably, has an emotional nit to pick with CO2. It cost him a triumph.

      But for those not betrayed by CO2, it serves the purposes you described. It is quite practical in addition to fun.


      • Michael,
        BB is a kinder gentler soul than I am.
        In his shoes, I’d likely have done “bad things” to that Chameleon pistol.
        Thankfully, he ensured it had a good new home. 🙂
        Blessings to you,
        P.S. 99.9% of all my shooting these days is just for the fun of it.
        As you do, I find CO2 adds to that fun. 😉

      • Mike

        He may have dropped a shot with the CO2 gun,, but giving up on it? I think that there were other things in his life that had as much or more to do with it. After all,, I am sure both he and you have heard the expressions ” Dance with the one what brung ya”.

        His CO2 pistol is what he used to reach the higher levels he had achieved. It very likely, with the additional foresight brought on by this episode, have carried him as high as he chose to go.

        But looking back, if one were able to correct mistakes made, the results “down the road” would not be foreseeable. His dropping the sport at the time is, in part, what brought him to us as the “Airgun Guru” we have come to know and love. Wouldn’t have it any other way.


  2. B.B.
    It looks like you really wanted to get rid of that question mark in the title.
    Speaking for myself that 20 years old Brno Tau 7 will be, along with the HW 45, with me as long as I can foresee…

  3. I myself have never really been a big fan of CO2. I know many people like the convenience of those “little silver bottles”, but where I live the nature of the beast can be most limiting in when you can shoot. I have been known to be camping, out shooting, hunting, hiking, etcetera and be quite bundled up. Yes, I own snowshoes.

    It is also well known that for various reasons I am not a big fan of these replica airguns. To each his own, I guess.

    Do not get me wrong. I have played with some of these over the years. The fully automatic ones can be quite entertaining for a short time. I even possess a very nice 2240 at this time. It does not compare with my Izzy, Beeman or Webleys. It is my personal opinion that it needs to find a new home.

    As I said, I am not a big fan of CO2. If one of you folks likes this stuff, that’s fine. The only CO2 guns I can possibly see me wanting were made a long time ago. 😉

    CO2 yes or no?
    … If yoO2u (you) have to know…

    • Michael
      I couldn’t agree more. Obviously we become rather snobb as we proceed with our experience in -airgun- life. Still it’s nice to enjoy the fun of it.
      Now, if only we could have fun with quality and a little more power, that would make our CO2 airgun life even happier…

      • Bill,

        That Snobbish shootski has any number of CO2 guns and even enjoys shooting them! I guess I just don’t have the PTSD (Post Traumatic Shot Drop) that the Godfather of Airguns® suffers with.
        “Now, if only we could have fun with quality and a little more power, that would make our CO2 airgun life even happier…”
        Power? You want POWER! YOU CAN’T HANDLE the power of my DAQ .25 2250 based with DAQ bulk fill screw in conformal tank 16” custom high volume/high flow valve barreled shooter. LOL!
        The heyday of CO2 modification may have been two decades ago. What, where, why and when do you think steel breeches started?
        There were some real CO2 shooters being built back in the day!

        Missed it…Huh!


        • OK, OK I missed that airgun days and now I miss them…
          And don’t be that flattered because when I said snobbish I meant those of us who believe in springers as the holly grail (let’s hope that R.R. and Yogi do not read this). You keep your place in the Dark Side of the Moon.

          • Bill,

            Lol! One of the questions on the Psychological Test for admittance to a US Navy Officer training program was:
            If given the choice which would you choose to be?
            a. A slob
            b. A snob

            I have no idea which was the correct answer or if there was a correct one; but i have my suspicions.

            With all the modifications my DAQ .25 Caliber CO2 pistol could shoot the KODIAKS very well.
            I may just need to get it out of the Gun Room and charge it up to see how well it shoots the newer pellets and Bullets (Slugs) especially since the ambient temperatures will be in the 90°+F (32°+C) range for the next few days so the CO2 will be cooking!


  4. I’m a big fan of the CO2 guns from Crosman. The 2240, 2250 and 2260 are easy to service, accurate and convenient to shoot for me. They’re also readily modified to work for whatever perceived needs one has.

  5. BB

    I like them all, especially the one I happen to be shooting. Oldies are always a looking forward to in my shooting rotation. My 74 year old Crosman 100 is not particularly accurate, is a beast to cock for arthritic fingers, has a pre lawyer trigger, is a joy to pump and really fun to shoot. Even my Chinese B-2 clunker is fun because it has a barrel hinge locking lever, something I wish every break barrel had. CO2’s work for me because I’m target shooting informally for score and I know to waste some CO2. I also waste compressed air on my PCP’s for the same reason. But air is free you say. Well it takes time to refill and time is worth something to me. Each type has its pluses and minuses. My Avenger rifle is now the new top gun on deck in the accuracy department. Sorry FWB300S, not even close at 25 yards. But hey that’s a 10 meter rifle.

    Last but not least, they are all eye candy to me!


    • BB

      Correction to my comment above is needed.
      “I also waste compressed air on my PCP’s for the same reason. But air is free you say.”
      My bad, no compressed air is wasted because it gets topped off. It takes time to refill a PCP and time is worth something to me.


  6. Feel B.B.’s pain regarding that blown transmission. We owned a 1994 Dodge Intrepid whose transmission failed at 103,000 miles; the planetary gears went flying into another dimension. The transmission had been serviced a week earlier by the dealer…Chrysler/Dodge products have not been welcome at Garage FM ever since. On the other hand CO2 replica shooters have their place here. FM notices there is a CO2 blowback P08 listed in Pyramyd’s latest catalog. 😉 Enable thyself, FM.

  7. Speaking of the caveats about CO2, such as letting a bottle or cylinder get too hot – you all enduring that brutal heat out there in Texas, be careful. It is not that much better in Florida, though the iguanas would disagree.

  8. I like my CO2 guns a lot. I will add that I live in a cold climate. It is 58 degrees and misty cool rain right now. My old vintage Crosman 114, 113,118, and the pistols, the 116 and especially my 112 which are bulk fill guns are accurate and cheap to shoot. My Shark .22 cal RB pump action 25 shot repeater is perhaps the most fun and effective pest gun I’ve ever used, and I have used all of them. I use “F” shot in the 118 and the Shark. About $45 for over 3000 shots and I use it in my 118 as well, and those don’t jam in that118 like pellets sometimes do. I agree with the poster who likes the 2240 platform. Lego platform of air guns.

  9. I like CO² as well. I think of it as my toe dipping into the dark side. I enjoy refurbishing, testing, and making presents of Crosman Mark I and II pistols.

    My next CO² related project will be resealing an AR2078 (a QB 78 with a thumb hole target stock, which is based on the vintage Crosman 160). My experience with it is that it is very accurate, but the seals failed just after P.A.’s return period expired. I chalk that up to cost-cutting and the country of manufacture. But in this case, I don’t mind so much because it gives me an excuse to tinker. I can mod this one too, so there is lots of potential for fun projects.

  10. Dave and RG ,the Shark is made in Argentina and was even reviewed by BB several years ago in Shotgun News. Pyramyd carried the gun briefly. I bought mine off ebay several years ago. It is a 25 shot ,.22 cal RB shooter that is a bulk fill gun . You fill it with a paint ball tank. Gets close to 700fps from the ,22 cal RB on a warm day, and is quite accurate at 10m. It has grooved receiver for a scope (I use the open site on mine) . Will easily shoot right through a pine 1X at that distance. Takes fair amount of strength to pump the action which cocks the gun and loads a RB from the non-removable magazine, which is spring fed tube alongside the barrel. All wood and steel , adult size gun. You can also load a regular pellet singly through the generous loading port in the top of the barrel. Shark has a web site and you can see the gun there as it is still made but they are a small company and their air guns are not common in the states. The ammo of choice was the Lobo RB . But ,Gamo .22 RB worked very well. During the covid period , those were not available so I tried the “F” shot which is supposed to be ,220 dia. However it is actually .218-.219 dia which is what the Gamo shot is and has worked fine so far. The gun has accounted for many red squirrels, chippy’s, and also rats at the bird feeder and around the gardens. As for the “F” shot, YMMV, so precede at your own risk. I wish Pyramyd AIR would carry them as well as their other bulk fill air guns. They also had a very nice .25 cal bolt action SS.

  11. When Co2 revolvers first came out we were very excited about them, unfortunately that didn’t last long.

    Where I lived then (Montreal, Quebec, Canada) the weather is often such that you can go from winter jacket to T-shirts to winter jacket again in the course of a day.

    Not understanding the affects of temperature on Co2 left us confused and disappointed. Power and accuracy were unpredictable, the cartridges added extra cost and always leaked (granted, we didn’t know to oil the cartridge).

    Not surprisingly, the Co2 pistols were soon traded away and everybody reverted back to slingshots which had more power with better range and accuracy than the revolvers.

    I can understand why people like Co2 guns. Replicas and automatic airguns are not my thing and Co2 can’t compete with HPA in the PCPs that I prefer so I can’t see having anything Co2 in my gun safe.

    Each to their own!


  12. BB
    I was not a fan of CO2 in my younger days, as the cost of the little bottles reduced the amount of ammunition (pellets/bb’s) that I could buy. Also, friends with CO2 powered guns always seemed to be out of CO2, when we wanted to go out and plink.
    Then came the M712 (many years later)! It has probably generated more smiles than any other pinker that I own. It is accurate (enough), economical (enough) and since it is way affordable compared to any original broomhandle, perfect for me. In addition, flipping the switch to ‘rock & roll’ can generate smiles at any get together (like a 4th of July picnic). I have enabled two of my friends into ownership, one of whom rolled his eyes when I said ‘let me show you my new bb gun’ (he had already researched and ordered it online, by the time I arrived home).
    CO2 definitely has its place at my house and if you haven’t tried it, give it a shot.

    • B.B.’s positive evaluation (2014) of the lowly Crosman 1077 (“…. needs nothing more than pellets and CO2 to get the job done. I’ll never get rid of mine!” ) sold me on getting one.

  13. I’ve just checked Hatsan’s website and saw the new prices. Models like Zada, Striker, Edge, Airtact are well priced, but models such as 65, 95, 125 are becoming pricey. I believe Hatsan should sell 65, 95, 125 models without scopes and keep their prices lower. Any breakbarrel that comes with Quattro trigger should come without scopes. Also, how about adding the MOD 35S to the US product line? With it’s adult size stock / LOP and max. muzzle velocity of 650 fps, it’s what the airgun community here wants lately.

      • Max. Muzzle Velocities of those two rifles have 10 fps difference when compared – perhaps, different powerplants. MOD 35S has Quattro trigger; it comes with Hatsan’s more premium features. My theories based on specs on paper; I’ve never seen the rifles in real life.

  14. Co2 is just another airgun option. Not a this or that decision for shooting them. Each has its own time and a place for use.

    All the fun without the work. Perfect for all those replicas. Great for entertainment, especially with full auto. Backyard and indoor friendly, and great for introducing younger, and older, people to airguns.
    Granted it’s a stepdown in performance once you get into more powerful airguns.
    I’m not going to criticize my Hyundai Accent because it won’t lay rubber at 60 mph when I step on the gas like the Veloster. It gets much better gas milage. Options are good to have.

    Co2 airguns with adjustable power settings are outstanding. My first was a Healthways Plainsman with a hammer spring adjuster. I think venting CO2 cartridges into a cavity when punctured slows down the cooling effect.

Leave a Comment

Buy With Confidence

  • Free Shipping

    Get FREE shipping on qualifying orders! Any order $150+ with a shipping address in the contiguous US will receive the option for free ground shipping on items sold & shipped by Pyramyd AIR during checkout. Certain restrictions apply.

    Free shipping may not be combined with a coupon unless stated otherwise.

    View Shipping Info

  • Shipping Time Frame

    We work hard to get all orders placed by 12 pm EST out the door within 24 hours on weekdays because we know how excited you are to receive your order. Weekends and holiday shipping times will vary.

    During busy holidays, we step our efforts to ship all orders as fast as possible, but you may experience an additional 1-2 day delay before your order ships. This may also happen if you change your order during processing.

    View Shipping Times

  • Shipping Restrictions

    It's important to know that due to state and local laws, there are certain restrictions for various products. It's up to you to research and comply with the laws in your state, county, and city. If you live in a state or city where air guns are treated as firearms you may be able to take advantage of our FFL special program.

    U.S. federal law requires that all airsoft guns are sold with a 1/4-inch blaze orange muzzle or an orange flash hider to avoid the guns being mistaken for firearms.

    View Shipping Restrictions

  • Expert Service and Repair

    Get the most out of your equipment when you work with the expert technicians at Pyramyd AIR. With over 25 years of combined experience, we offer a range of comprehensive in-house services tailored to kickstart your next adventure.

    If you're picking up a new air gun, our team can test and tune the equipment before it leaves the warehouse. We can even set up an optic or other equipment so you can get out shooting without the hassle. For bowhunters, our certified master bow technicians provide services such as assembly, optics zeroing, and full equipment setup, which can maximize the potential of your purchase.

    By leveraging our expertise and precision, we ensure that your equipment is finely tuned to meet your specific needs and get you ready for your outdoor pursuits. So look out for our services when shopping for something new, and let our experts help you get the most from your outdoor adventures.

    View Service Info

  • Warranty Info

    Shop and purchase with confidence knowing that all of our air guns (except airsoft) are protected by a minimum 1-year manufacturer's warranty from the date of purchase unless otherwise noted on the product page.

    A warranty is provided by each manufacturer to ensure that your product is free of defect in both materials and workmanship.

    View Warranty Details

  • Exchanges / Refunds

    Didn't get what you wanted or have a problem? We understand that sometimes things aren't right and our team is serious about resolving these issues quickly. We can often help you fix small to medium issues over the phone or email.

    If you need to return an item please read our return policy.

    Learn About Returns

Get FREE shipping on qualifying orders! Any order $150+ with a shipping address in the contiguous US will receive the option for free ground shipping on items sold & shipped by Pyramyd AIR during checkout. Certain restrictions apply.

Free shipping may not be combined with a coupon unless stated otherwise.

View Shipping Info

Text JOIN to 91256 and get $10 OFF Your Next $50+ Order!

* By providing your number above, you agree to receive recurring autodialed marketing text msgs (e.g. cart reminders) to the mobile number used at opt-in from Pyramyd AIR on 91256. Reply with birthday MM/DD/YYYY to verify legal age of 18+ in order to receive texts. Consent is not a condition of purchase. Msg frequency may vary. Msg & data rates may apply. Reply HELP for help and STOP to cancel. See Terms and Conditions & Privacy Policy.