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What is that wisp of CO2 at the muzzle?

by B.B. Pelletier

This one comes from a comment made by Canadian reader Wild Wild West. “Speaking of whisps of CO2, I am not sure if you or any of the other Nightstalker owners have noticed, but on my Nightstalker with a fresh bottle and during the first 100 or so shots, I do get quite an annoying blast of CO2 following each shot.”

Yes, you will see that on many CO2 guns, and today I’d like to examine why.

Liquid or gas?
The way some CO2 guns are designed – whether it’s a full powerlet, removable bulk tank or new AirSource cartridge – it’s possible for liquid CO2 to flow into the gun’s valve when the gun is held level. The liquid CO2 cannot maintain its pressure once it’s released from the confines of the tank, so it flashes to gas wherever it happens to be. If that is inside the valve of a gun or even beyond the valve and inside the gun’s barrel, the CO2 does not have enough time to completely expand before it hits the outside air – still expanding. Because it cools as it expands, it instantly condenses the moisture in the air, creating a fog. The moister the air, the more fog is created.

Vertical vs. horizontal
If you look at AirSource guns, almost all of them align the cartridge horizontally, which means the liquid CO2 inside the full cartridge has the best chance of flowing out when the gun is fired. Now, the AirSource adapter upgrade kit, used to upgrade a standard Crosman 1077, positions the cartridge lower than the rifle’s valve, preventing this from happening. The small amount of vertical space in the adapter allows CO2 gas to rise above the liquid and get to the valve first.

The Crosman NightStalker has the AirSource cartridge aligned horizontally in the butt, so it is a candidate for liquid to flow through the valve. A Benjamin EB 17 pistol has a 12-gram powerlet aligned horizontally with the valve in a tube at the front of the gun, so it is also a candidate for a wisp of fog with the first few shots from a fresh powerlet. On the other hand, a Colt Government Model M1911A1 pistol has the 12-gram powerlet aligned vertically inside the grip, so there is less chance of liquid passing through the valve. A gun like this is a lot less likely to have the wisp of fog from the muzzle on any but the hottest, most humid days.

What about the “dog days”?
There are days when the temperature is so high and the humidity is 100 percent that ANY CO2 gun is going to give a wisp of fog from the muzzle. On days like these, the air is completely saturated with moisture, and anything that changes the conditions for even an instant causes condensation. Just the relative coolness of the CO2 gas is enough to cause visible condensation on a day like this. Heck – even a PCP will smoke on some days for the same reason. I have seen water dripping from the wings of low-flying A10 Warthogs when they turn sharply close to the ground, simply from the air they compress ahead of the wing! They will actually leave brief vapor trails!

So what? Now that we know the science behind the smoke from CO2 guns – does it matter? As a matter of fact, it does. If an airgun is passing liquid – instead of gas – through the valve, you can expect the velocity to be way off the norm. If you chronograph the gun, that’s exactly what you’ll find. The first couple of shots from a CO2 gun – ESPECIALLY a gun with a horizontal tank – will be significantly faster than the norm. Then the gun will settle down to a long string of shots in close proximity until all the liquid is gone. Then, the velocity drops sharply.

So a target gun that uses CO2 will have a couple of wild shots before it settles down. That explains why the FWB C55 changed from a horizontal to a vertical gas tank and also why CO2 is not considered competitive at the world level anymore.

“Gee, Mr. Wizard, you sure can tell a lot of neat stuff from just a puff of gas at the muzzle of a gun!”

“Yes, Jimmy, you can.”

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.

34 thoughts on “What is that wisp of CO2 at the muzzle?”

  1. Have what I guess is a hy-score 804 repeater..22 cal barrel only..blue..pressed ingraved

    I am original owner (guess 53 years old)

    How would I sell, and or acertain its value?

    Works..no rust. Really decent condition..no paper work
    front hinge bolt has been re-placed with nyla-lock
    small crack (glued in hand grip by slide release)

  2. frank,

    Unless you live near an airgun show, the internet auction sites are your best bet.



    The value is listed in the Blue Book of Airguns, which is sold on this site


    Blue book says $190 to $255 in the condition you describe.


  3. B.B.,
    Does this puff of gas with the Night Stalker also indicate a decrease in the number of shots you will get from an Air Source bottle? And you are right; the first few shots are really high powered. I couldn’t believe the 700+ fps I got with the first shots but it did settle down. It also seems not to get as many shots fron a canister as I would expect which is discouraging since the Air Source canisters are so expensive. On balance, it is a fun gun to shoot and does well with a red dot scope.

  4. But Mr. Wizard, Why is the Steyr LP1C (Co2 version) Air pistol is still being used in world 10-meter air pistol championships? It has a horizontal mounted tank. Looking thru the website, I hardly see any shooter use the FWB 55C in competition. I also see shooters at the National and World level competitions use the FWB C60 and C62 and those are air rifle with a horizontal tank. Why is that Mr. Wizard?


  5. Dear Mr. Wizard,

    Yes, I have a Steyr LP1C. When I first put on the charged Co2 tank onto the LP1C and begin shooting, I don’t see any wild shoots at the beginning like you claimed. Why is that? I will try to chrony it tonight after I inserted a fresh co2 tank into the gun to check if the velocity of first two shots is significantly different than the rest of the shots as I continue to shot.


  6. airgundoc,

    Honestly, yes, when you see a puff of gas at the muzzle the gun is using a little too much gas. But the amount is very small and I doubt you loose as many as 10 shots per 88-gram cartridge.

    Crosman came to market a little strong with the AirSource. Instead of saying “300 shots or more” they first said 400, then backed off to 350 and now I think they wish that the numbers would just go away.

    How many shots YOU get depends on the ambient temperature where you shoot. Shoot in 50 degree F weather and the shot count will be low. Shoot in 80 degree F weather and it will be higher – from the same gun.

    Best I can offer,


  7. Jimmy,

    First, you should NEVER see an FWB C55 in any 10-meter pistol competition because it is a five-shot repeater. No real competitor would use a repeater in 10-meter competition. That model exists for other sports that are not yet world-class.

    Second, when I was talking about world-class competitors, I wasn’t referring to shooters from Botswana or Chad. I’m aware that anyone can represent a small country in any sport at the world-cup level, but those aren’t the real competitors.

    The shooters I’m talking about shoot Steyrs and Tesros, with a smattering of FWB, Walther, SAM, Anschutz, Hammerli and perhaps one or two other TOP air pistols (all pressluft/PCP) thrown in. CO2 is not competitive at the world level any more.

    Now, all you guys who own CO2 target guns don’t need to throw them away (but if you feel so inclined, I will start a reclaimation program where they will be given to other needy shooters). They still work, as do the IZH 46, Aeron 99, Benelli Kite, etc. They are great guns – but don’t expect to take them to the Olympics.

    Jimmy, if I’m wrong about this, I will admit it. Can you supply the name of a competitor using a CO2 pistol who has won even a bronze at the world or Olympic level in the past five years?

    Mr. Wizard

  8. Dear Mr. Wizard,

    Per your request, here is the link to show that Co2 target guns are still being used


    Note that C20 is an old FWB 10-meter air pistols.
    Also note that only Steyr LP1 is shown, They didn’t separate them out as LP1C or LP1P. I wish they did.
    Walther CP3 is also a Co2
    Note the C60 air rifle (yes, Co2)

    May I rest my case, or should I try to find more?

    Your Pal,

  9. Dear Mr. Wizard,

    Jason Dardas shoots a C62. Check out his scores at the some of the recent air rifle matches at the Olympic Training Center (www.USAshooting.com). Yes, a FWB air rifle with a horizontal tank. Because of shooters like him, more competitors are looking for FWB C60 and FWB 62. I think you can find those people in “target Talk (www.pilkguns.com). The C60 and C62 have a pre-staging chamber (I don’t know what that is) that FWB claims …keep velocity constant when ambient temperature changes. FWB guarantees that velocity of these two guns remains constant even when ambient temperature flexes between 5 C to 30 C (41F to 86F). WOW!

    Your Pal,

  10. Jimmy,

    How about some world-class medals?

    I compete in regional matches in which Daisy 777s and IZH 46s have pulled down scores above 550. I’ve even seen a Crosman Skanaker hit 575!

    What I am talking about are not the regional or even national hopfuls who might score the occasional 580 (in mens air pistol). I’m talking about the shooters who are standing on the podium when the final ten shots have been fired. Can you show me some of those who have used CO2 pistols to win in the past five years? Not in regional matches but at the world level, which, after all, is the whole point of competitive shooting.

    Your pal, too,

    Mr. Wizard

  11. Jimmy,

    A “pre-staging” chamber is a place where any CO2 liquid is forced, through the design of the chamber, to expand and evaporate to gas. They need that in a gun with a horizontal tank BECAUSE LIQUID CO2 POSES THE PROBLEM I MENTIONED EARLIER – IT CAUSES IRREGULAR VELOCITIES!

    The pre-staging chamber is an attempt to prolong a technology whose time has passed from the world stage.

    That said, I shoot a CO2 pistol in competition. Why? Because it’s the best target pistol I own. But would I buy a CO2 pistol as my next target pistol? Only if I were so contrary that I would also drive a 1963 Plymouth Valiant because I think pushbutton transmissions are cool!

    You keep watching Jason Dardas. If he continues to rise on the world stage, he’ll have a new pressluft rifle in his hands before long.

    CO2 is dead at the world-class level of competition. Or at least those who win all the medals seem to think so.

    Your pal,

    Mr. Wizard

  12. Dear B.B.,

    When a shooter steps up to the firing line, he/she brings with him the gun that he BELIEVES that will take him to the promised land (or a trip to the podium to receive the highest honor that can given to a humble shooter). It doesn’t matter what that gun is. It can be a cheap Chinese airgun or a Crosman 1077. As long as he believes deep down in his heart that this gun will get him the Olympic gold, that is the gun he will use. In the 1984 Olympics in Los Angeles, the air rifle shooters didn’t believe that a Co2 rifle will taken them to the promised land. Most used Pneumatics. This doesn’t mean that Co2 match rifles are not as accurate as a Pneumatic (or PCP), they are. It doesn’t mean that a Co2 cannot take them to the promised land. It was a “believe”, that these top shooters have, and rightfully so! Why you ask? The shooting event was in Chino Hills during 1984 Olympics. Did you ever walk into that 10-meter shooting range (indoor building) in the middle of the summer? Not even the FWB C60/C62 can guarantee constant velocity, because that guarantee stops after 86 degree F. That 10-meter range at Chino Hills can reached the upper 90s. If they put an AC in that building, HISTORY would be different, and I can rest my case. But the 1984 Los Angeles Olympic organizers were too cheap, thus no AC. They were even too cheap to put in electronic target systems. Yes, they shoot into paper.

    In Air rifle, Co2 never was given a good chance, because PCP came right afterward, and of course it is better, it MUST, else FWB, Walther, Anschutz…etc didn’t do their homework. Who was the one that said “I build upon the shoulders of giants.”?

    Sometimes to be a success in life, all you need is to be in the right place and at the right time.

    Your humble,

  13. Forgot to mentioned Mr. B.B., that the 1984 Olympics was the first time that airguns became official Olympic events. Also we all know that 10-meter airguns were design and made long before 1984. Co2 airguns never really got much of a chance.

    Your humble,

  14. BB,

    Scince gamo made the raptor pellet,will new gamos have a new rating.I mean my cf-x has a sticker that reads”1000fps high power air rifle”Will the cf-x tested after the raptor will be rated at a higher speed?

    CF-X guy

  15. Jimmy,

    Your right that CO2 pistols were tops in 1984. But, 84′ is just a cheap memory on some fat guy’s shirt. Florida ’84! BB is correct in that the top rung of mens pistol shooters today shoot PCP’s.


  16. Ya well only down here in florida and the immediate gulf coast can you have days outside of rain with high temperatures with complete saturation,trust me I know alot about the weather,I would know.It it would have to take a freak weather pattern change for that to occur outside of the imeddiate gulf coast in the continental U.S.,even down here complete saturation is hard on a warm humid summer day if it hasnt rained yet,temperatures in the upper 80s or better hold many more times as much moisture as temps in the 50s.It is interesting,you know if that co2 becomes warm enough you wont see it,I have only neumatic sinlge shot air rifles,but I do have a paintball gun that is co2.See the dew point needs to be near or below the dewpoint to condense signifcantly,I have seen dewpoints as high as 80 here,so in the summer co2 will heavily condense at the muzzle even if it is warm.

  17. BB,

    exactly!!!!!!!!!!!The gamo 1250 example was great!!!!!!!!!.I see you understand me and I guess you are right.But I belive that gamo raptors will be the pellet used to rate airguns so they can say they are fast.And if a lighter pellet comes out,I think the companies will use them.I know what you meant by the 1st stage in the post.When I bought the cf-x I wanted a 1000fps gun.I saw the.22 cal but sayed that they are too slow.But now by reading this blog every day I understand.I think my next air gun will be the rws diana 350 magnum in .22cal.{heavy pellets,slow but fast speed{you get me}good trigger,accurate and german made{im a german fanatic-BMW’s RWS and Beeman}Well I guess that theyll some day make a pellet that is so light that it will put the most powerfull airguns to shame.One day,maybe very away from now.That was kind of poetic.See ya!!!

    The guy that loves this blog like no other person:

    CF-X guy

  18. Dear Jason,

    I think my view of Co2 airguns came from my positive experience with Match airguns. I never own a co2 airgun that is not of match quality. Perhaps I should go out and buy a cheap co2 airgun, than I will see all the problems that B.B. is talking about.

    Your lowly shooter,

  19. Jimmy,

    I agree with you that on any given day a shooter of great skill could win and dominate with a high quality match CO2 pistol but, they don’t. As you stated, BB was talking about CO2 guns in general, not necessarily match guns. The makers of high quality match pistols and rifles have taken measures to keep this effect to a minimum. You seem to really like your CO2 airguns, and obviously haven’t noticed any of the bad manners stated in BB’s blog with them. I think that is great! I didn’t mean to rain on anybodies parade. Go for Gold. “Cheap CO2 airgun”… now that’s just plain hurtful Jimmy.


  20. Humidity,

    Actually, warm air holds less moisture than cold air. The humidity is usually higher when it’s warm because humidity is relative, and warm air can’t hold as much moisture as cold.

    Check this out on the weather sites.


  21. Jimmy et. al.

    I’m sorry but I just can’t let this discussion continue without remarking! CO2 is NOT the gas of preference for top world shooters. Jimmy even recounted one reason why – it’s temperature dependant.

    Yes, match guns DO have the problems I mentioned, which is why Feinwerbau, a company who builds great match airguns, went to the expense of changing the horizontal gas tank on their C5 to the vertical globe-type tank on the redesigned C55. Some guns may have design features that accomodate CO2 better than others, but the physical problems still remains.

    Jimmy, I agree that desire and focus are more important to match shooters than the type of powerplant they use, and the accuracy potential of a top-quality gas pistol is equal to that of a pneumatic. But CO2 has drawbacks that the entire world has acknowledged, and no amout of excuses can change that fact.

    Pneumatic airguns are the technology of today. I didn’t make it that way, but I’m also not going to write lies because the truth hurts someone’s feelings.

    You will continue to shoot a CO2 gun and love it. I will do the same and wish I could afford a Steyr LP10. Life goes on and there are still choices for everyone.


  22. Hello B.B.
    I chrony my Steyr LP1C yesterday night, and this is what happened…
    I charged my Steyr cylinder tank up to recommended weight (Yes, I weighted on a postal scale), then screw it into my steyr LP1C. The muzzle is about 3 feet from the chrony. I dim the room light and turned on the lamps that are sitting on top of the chrony’s sensors. Without shooting any shoot, I shot the first 10 pellets thru the chrony. This is what I found
    Average velocity = 539.3
    Highest velocity = 544.5
    Lowest velocity = 532.9

    Wow, I was surprise to find that a 10-meter air pistol is shooting this hard. I am glad I did this. Your Blog is great, full of insights. Also it got my fat As_ off the chair and did something for a change. 🙂


  23. KYW,

    Thanks for sharing that data with us. Yes, your pistol is cookin’! Of course you know you can turn the velocity down a bit with the adjustment screw, but if you’re getting the accuracy you want and the recoil is not disturbing, I’d keep shooting it the way it is!

    How I envy you, owning a Steyr!


  24. Dear B.B.

    I love all well made airguns, especially the ones that are accurate. My main problem is that I love all different types of airguns with EQUAL affection, be it spring, PCP or co2, and not just certain type. Because of this, I like to see all different types to have an equal chance in the sun. I marvel at the sight of knowing a poof of air can hurl a pellet 45 yards down range and striking a metal ram target and sending it flying backwards. Like you said before, I just reached a state of airgun enlightenment.

    Airgun Buddha (a.k.a. Jimmy)

  25. A CO2 related question I have is how do people with bulk fill CO2 guns refill them? Where do you get co2? Silly question, perhaps, but I sincerely haven’t a clue.

    Great blogs by the way! Thanks!

  26. Jim,

    Thanks for the suggestion for a posting next week. But I’ll answer your question now.

    When you become a bulk-fill shooter, your buy one or more bulk tanks. They can be large fire extinguishers or soda fountain CO2 bottles. The point is, they uniformly hold 20 pounds of liquid CO2.

    You buy the tank and the gas from one of two sources – either an industrial gas supplier or a restaurant supply house. The industrial gas supplier refills the tank when needed.

    The tank must be set up in a certain way (by whoever sells it) to work best for airgun filling, and I will cover that in my post. In fact, this may take several posts to cover completely.



  27. talk to a weather expert,torrential rains are from warm humid locations,himidity is relative,relarive to the temp,the higher the temp the lower the relative humidity,why?Because a warm airmass holds more water vapor,but it needs cold air to condense the water vapor,trust me talk to a meteorologist I am 100% if you talk to a real metorologist,he would agree 100% with me on this issue.Tropical regions receive much stronger storms and hevier rain then in cooler climates because warm air contains more water vapor and has more energy then cool air.

  28. About Steyr LP1C pistol: Correct me if Im wrong but Sergei Physianov have set the World Record with this pistol around 10 years ago with a score of 593. His record is still unbroken.

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