The 1873 Giffard was the first rifle powered by carbon dioxide. How should it be tested?
This report covers:
- Easy!
- What about…?
- Rifles
- The deal
- Summary
In Parts 1 and 2 of this series we talked about spring-piston and pneumatic airguns, respectively. They were easy to test compared to today’s topic. Today is a toughie! How should you test a CO2 gun?
Easy!
Come on, BB. Don’t make a mountain out of a molehill! Just load the 12-gram cartridge into the gun and shoot it. You know at the start how much gas you have and what it’s going to give you. If it’s a pistol you’ll get about 60 good shots. That’s it!
What about…?
What about a Crosman 600 that only gives 30 shots per cartridge?
Crosman 600.
Okay, that’s different, isn’t it? Some of the gas has to operate the semiautomatic loading and cocking mechanism. I’m talking about airguns like the Glock 19 BB pistol you just tested. Oh, you mean the one that gave me 80 good shots?
That was an anomaly. You know to expect 50-60 good shots from a CO2 pistol. And less if it’s a semiautomatic.
Oh, I see. you mean like the APP661 semiautomatic BB pistol that gives more than 200 shots? But that was on an 8-gram cartridge, not a 12-gram.
APP 661.
Well, that one was just different. Take something that’s standard like a pellet pistol. They should give about 50 good shots.
Okay, then why did the Dan Wesson Valor 1911 pistol give me 180 shots?
Rifles
Forget CO2 pistols, BB. Let’s talk about CO2 rifles.
Okay, this report began with the picture of an 8mm 1873 Giffard rifle. How many shots should I expect from it? And how fast will it shoot, because I have to stop an 8mm / .32 caliber bullet that weighs 45.5-grains?
I don’t know. Ten shots? Fifteen? Somewhere around there I would guess.
I got four good shots. Hmmmm.
Let’s look at something more modern. How about a Springfield Armory M1 Carbine BB gun? When I tested mine I got 36 shots from a 12-gram CO2 cartridge
The deal
What I’m dancing around today is the fact that—just like pneumatics, CO2 guns are unpredictable. Yes we’ve tested many that performed as expected and without surprises. We can make generalizations about many CO2 guns, but don’t make assumptions because there’s stuff out there you think should work one way and it doesn’t.
Now, the gun up top is a Giffard from the 1800s. I had no idea how it would perform, but I do know some things that never change.
1. No matter how large the reservoir is, the pressure of the gas in a CO2 gun will always be the same until the gas starts running out. It’s based on temperature, not volume. Take a 500cc tank and squeeze it down to 250 CCs and the pressure inside doesn’t change. All that happens is more CO2 gas turns into liquid.
2. CO2 molecules are large and move more slowly than air, so you can expect less velocity from a gun on CO2 than the same gun on high-pressure air.
3. After a certain velocity CO2 just won’t push a projectile any faster. The same holds true for air, though air will reach a higher velocity than CO2, all things being equal.
4. To get power with CO2, increase the projectile weight. I remember seeing CO2Much hit 1,082 foot-pounds with a 7.4 ounce bullet. That beats every other CO2 gun ever made.
Knowing all of this I estimated that the Giffard could not launch an 8mm round ball any faster than 600 f.p.s. and 500 f.p.s. was probably closer to the real top. The fastest single shot I saw with my rifle in my test was 540 f.p.s.
Summary
When shooting guns that use CO2 gas you need to understand a little science. The gas has properties that are unique and the performance of the guns that use it will conform to those properties. You may know nothing about the airgun you have to test, but knowing about the gas it uses will tell you a lot about the gun’s expected performance.
I immediately thought about the shot count per CO2 cartridge and realized I never counted the shots per cartridge on each of the three power settings on my Plainsman, or any other CO2 air pistol. Always keep changing the power setting while shooting and to be honest, I never cared. Not much I could do about it.
I knew I would get less on high power, but the increased performance was worth it.
I really enjoy that power option and got to thinking why don’t more CO2 airguns have a power option? All it is, is increased hammer spring tension.
Off hand, the only other one I could think of that does is some of the Crosman Mk 1 & 2.
Any others out there I’m forgetting?
Bob,
The Crosman 150/157 pistol and 180/187 rifle also have striker spring (power) adjustments.
BB
Crosman 2300S?
I know that my Challenger 2009 has that and if I’m not mistaken, so does my Marauder (original model), I could be mistaken on that as I have not shot the latter in a number of years. All of mine have become closet queens. I hope to survive long enough to remedy that, tho.
Ed
edlee,
You are not mistaken on “…striker spring (power) adjustments.” I use the striker (hammer) spring preloading adjuster from the Challenger on my Benjamin Discovery.
The Benjamin Marauder has that spring capability and also the striker length adjustment to boot.
Not to mention the ability to throttle the Transfer Port (TP) they may be ”old” compared to all the new airguns since but they are able to be very competitive on accuracy with a bit of care and tuning.
Get those Stellar Queens out of the closet and shoot them asap! :^)
shootski
Bob,
do you know what velocity you are getting out of your Plainsman? Just wondering. I’ve never shot one but they sure look neat.
Doc
Doc,
I have not done a velocity test on any of my CO2 pistols, or rifles. They don’t vary too much from one to another unless there is an outstanding difference. I installed a longer Crosman 2100B barrel on my Hellfire Hellboy and it increased the FPS a lot. Over 500 FPS result I believe been a while.
BB did a blog on the Plainsman. Part 2 has velocity tests. The Vintage .22 lead ball NOS 60’s ‘Plainsmaster’ I have with a longer barrel did not do well when I shot it. Very slow and almost useless. Still needs looking into.
When I’m not resting from hurting myself clearing property for this season’s wildfire events and repairing cars, I’m doing catchup work on everything else and filling the needs for two disabled people.
I have a dozen airguns or more I would like to dig into and check out, including the latest a CO2 SVD Sniper Rifle and I will share anything interesting when I do. Especially curious about the FPS of the Barra 1858 Cowboy Pistol, Umarex SA10 and Daisy 5170. (Had to smooth out the trigger guard to avoid pain on that one) It claims 520 FPS.
It uses a spring-loaded barrel assembly like the M11 pistol to strike the air valve. The trigger pushes it forward and lets a BB from the mag pop up into it.
The weather seems good for a while, but I really need an indoor setup. to save time.
With shooting indoors, the rubber mulch pellet and bb trap is your friend.
I would like to add some personal experience. I couldn’t find rubber mulch but cutting two feet of gardening hose (Vassili help me with the translation) to pieces was a solution. It absorbed the impact of 80 fpe from the M25.
Bill your translation is fine, see picture below, but 2 feet is only 2/3 of one meter. Hardly seems like enough to fill a box big enough to use as a target.
But your creative substitute for rubber mulch may give Siraniko some ideas.
It’s strange but the length of the hose was the only thing I was (almost) certain. You see the target box was a standard metal made for 14X14cm targets!
OK, mine is much bigger:
Bill,
Let us know how many shots the cut up hose will survive as you keep pounding it with your M25! Old hose rescued from the Tip/Trash is much cheaper than bags of rubber mulch; a great way to recycle as well.
shootski
The Umarex Morph 3x CO2 BB gun has two length barrels, the longer one generating more power, and a screw in the back that changes the power from Low to High. I don’t know what the screw does, whether it is some kind of transfer port or a hammer spring preload, but it is in exactly the place a hammer spring would be.
I have a CO2 adapter for my Airforce gun, but the power wheel (hammer spring preload), hammer weight, o-ring-under-top-hat, those tricks don’t change the power on CO2. What does work is a different orifice size in the valve/top hat, and of course the temperature of the CO2 bottle. So maybe adjusting CO2 power is different on different types of guns?
Tom,
There appears to be no single rule of thumb that can be used with CO2. You don’t even have a single method of loading. Different threads used when bulk filled. How big a CO2 cylinder does it use? Did it use one or two at a time? Hopefully this blog will remain for a long time as a repository of air gun knowledge that is fast becoming esoteric for most people.
Siraniko
PS Section The Deal #4. second sentence: “I remember seeing CO2Much (Mac 1?) hit 1,082 foot-pounds with a 7.4 ounce bullet.”
Siraniko,
I’m not seeing what you are saying here.
And CO2Much wasn’t made by Mac1
BB
Tom I think that you should also mention (once again) that barrel length, up to a point, is also a power increase factor in CO2.
Bill,
Good point.
BB
I guess the power and shot count is a compromise which each maker must consider regarding the CO2 powerplant. The tendency is always “the shot count first”, I’m afraid. People who like more power will go straight to PCP. Most people I know would rather have more shots form one capsule, than more power which costs 50% shot count.
What I’m missing is a Crosman 2240 mixed with Smith & Wesson M29 revolver. I have a 6,5inch version of the M29 and I can shoot easily like 70 shots in .177cal. That is OK for plinking and training – but how about to make it a .22cal with 30 good shots on the energetic level of Cros 2240? That would be my favorite revolver ever! In warm ambient the first 10 shots from 2240 are just boombastic – with some recoil, with a gas expanding cloud and up to even 9J energy. The M29 gives this pretty constant 3J and that’s all. Especially hard to take for people living in a bit disabled country, where there are indolent energy limits like 7,5J…
I would pay a lot of golden ones for a .22cal 12gram CO2 driven M29 revolver with 8J energy!
I do not see any .22 caliber barrel conversion kits for the Schofield revolvers available on the Barra website at this point in time. But they were available at some earlier point in time.
https://www.gatewaytoairguns.org/GTA/index.php?topic=214618.0
I have a 5”- .177 rifled barrel installed on my Schofield revolver. I will test the velocity with the heaviest .177 pellets I have and let you know the results.
Elmer Fudd,
Thank you so much! That would be a important information for me as I was really interested to buy this Schofield revolver. I already almost make the final click two times on it. I think there is also a conversion barrel available in Germany (rifled), the original is smooth bore. Nevertheless, from what I could read about it, even smooth bore is pretty accurate.
When I think about it, how fun it would be to have the 2240 performance in a revolver it makes me sad…
Tomek, here are some results using various pellets I have here (starting with the heaviest that I have).
Today I tested five different pellets in the Schofield revolver. Ambient temperature was 73-degrees F. A higher ambient temperature would help to increase the power somewhat. Also, BB has an excellent five part series on this revolver in the blog. Just do a search for it.
First is the Crosman Piranha 10.5 grain pellet.
Barra Schofield Revolver .177, Crosman Piranha
Shot count: 6
Low: 274 FPS
Hi: 358 FPS
Avg: 327 FPS
Spread: 84 FPS
STD Dev: 26.6 FPS
04-Jun-2025 07:49:06,358,FPS,3.0,FT Lbs,
04-Jun-2025 07:49:27,346,FPS,2.8,FT Lbs,
04-Jun-2025 07:49:44,322,FPS,2.4,FT Lbs,
04-Jun-2025 07:50:01,274,FPS,1.8,FT Lbs,
04-Jun-2025 07:50:21,327,FPS,2.5,FT Lbs,
04-Jun-2025 07:50:43,336,FPS,2.6,FT Lbs,
Next is the Benjamin Single Die 10.5 grain pellet.
Barra Schofield Revolver .177
Shot count: 6
Low: 327 FPS
Hi: 348 FPS
Avg: 335 FPS
Spread: 21 FPS
STD Dev: 7.4 FPS
04-Jun-2025 07:57:34,348,FPS,2.8,FT Lbs,
04-Jun-2025 07:57:48,335,FPS,2.6,FT Lbs,
04-Jun-2025 07:58:02,340,FPS,2.7,FT Lbs,
04-Jun-2025 07:58:14,330,FPS,2.5,FT Lbs,
04-Jun-2025 07:58:28,328,FPS,2.5,FT Lbs,
04-Jun-2025 07:58:40,327,FPS,2.5,FT Lbs,
Third is the JTS Dead Center 7.87 grains pellet.
Custom Profile
Shot count: 6
Low: 377 FPS
Hi: 420 FPS
Avg: 401 FPS
Spread: 43 FPS
STD Dev: 14.4 FPS
04-Jun-2025 08:04:03,420,FPS,3.1,FT Lbs,
04-Jun-2025 08:04:17,412,FPS,3.0,FT Lbs,
04-Jun-2025 08:04:31,408,FPS,2.9,FT Lbs,
04-Jun-2025 08:04:42,377,FPS,2.5,FT Lbs,
04-Jun-2025 08:04:58,389,FPS,2.6,FT Lbs,
04-Jun-2025 08:05:20,400,FPS,2.8,FT Lbs,
Fourth is the H&N Baracuda Hunter Extreme 9.57 grain pellet.
Custom Profile
Shot count: 6
Low: 346 FPS
Hi: 371 FPS
Avg: 359 FPS
Spread: 25 FPS
STD Dev: 8.4 FPS
04-Jun-2025 08:10:09,371,FPS,2.9,FT Lbs,
04-Jun-2025 08:10:33,366,FPS,2.8,FT Lbs,
04-Jun-2025 08:10:49,360,FPS,2.8,FT Lbs,
04-Jun-2025 08:11:16,346,FPS,2.5,FT Lbs,
04-Jun-2025 08:11:37,360,FPS,2.8,FT Lbs,
04-Jun-2025 08:11:55,351,FPS,2.6,FT Lbs,
Fifth and last is the RWS Hobby 7.0 grain pellet.
Barra Schofield Revolver .177
Shot count: 6
Low: 411 FPS
Hi: 440 FPS
Avg: 426 FPS
Spread: 29 FPS
STD Dev: 9.0 FPS
04-Jun-2025 08:22:59,440,FPS,3.0,FT Lbs,
04-Jun-2025 08:23:15,431,FPS,2.9,FT Lbs,
04-Jun-2025 08:23:36,428,FPS,2.8,FT Lbs,
04-Jun-2025 08:23:54,411,FPS,2.6,FT Lbs,
04-Jun-2025 08:24:14,422,FPS,2.8,FT Lbs,
04-Jun-2025 08:24:31,422,FPS,2.8,FT Lbs,
Thank you so much! Wow! Did not expect so detailed answer, and not so fast.
It looks nice. I have to look at it again… you are also a great enabler! 🙂
Tomek
It seems that we share the same dream. I have expressed such a wish here several times during the years I comment. My personal choice has always been a Colt 1860 (big grips) in 22 caliber in the widely accepted 7.5 joules area. Rifled barrel for sure. And the pellets should seat in fake percussion nipples, giving a very original look. The S&W came after my first “dream” but I fully agree with you. By the way if you search for the Webley in 22 caliber there is a site that claims they have them available in Europe. Wish you luck.
Bill,
Thank you for this valuable information. Unfortunately, I see that our wishes in this matter have not yet been fulfilled :/
Actually…
BUT WHY?
Vision is something that bean counters do not have. Anyway “denial to the trash” applies to people also.
Bill,
Unfortunately, “denial..” applies mostly to people.
I think your explenation is exactly the answer to “BUT WHY?”. There is no vision inside.
I have but one CO2 airgun here at RRHFWA. I have rebuilt a couple and they have moved on.
Recently, I rebuilt a Crosman 150. It was really very easy to do and quite impressive. I lost count of how many shots I was getting from one 12-gram CO2 capsule. It was well over fifty. You guys like this new stuff, but I am quite happy with what has gone before.
The latest and greatest ain’t always the bestest.
RR
Besides the Baikal Mp 654k I have kept a 2240 tricked out from times I could afford these things… But recently I had the opportunity to buy a 2300T, actually unused, for a very good price.
It has already earned its place next to the HW45, if that means anything. I don’t intend to “upgrade” it in any way. Just a pair of grips to make her look her very best.
Congratulations!
I think that congratulations should go to Ridgerunner. He is the one who mostly enabled me into the “old gulls”.
BB,
Like Siraniko, I was somewhat confused by your #4 under your section labeled “The deal”. I have never heard of the CO2Much.
Would you happen to have an illustration of one you can show for us?
RR,
CO2Much was a big bore (1.07 caliber) CO2 gun that competed in a big bore match I held at the Maryland Airgun Show. I’ll look and see if I have a picture. I remember it weighed 14.5 pounds and recoiled like a .375 Holland and Holland Magnum rifle.
BB
Now the sentence makes a lot of sense. It sounds like the airgun equivalent of the Mandalorian’s gun.
BB
I wonder about the size of a cartridge, plenum or bottle needed to get off even one shot.
Deck
Heat also increases power with C02, right? Not advocating heating up C02 cylinders to achieve that but since cold conditions conversely reduce the power of the gas, the hotter the ambient temperature the better the power curve? Believe this has been discussed before in these pages. Guess that is what makes S Florida C02-power friendly – lately, a summer day in the mid-to-high 80s (F) here is a good day.
Speaking of Gas Hogs, I can’t help but thinking of the Crosman 451. About 18 shots is it. But wow what a nice looking gun. A beast.
https://www.pyramydair.com/blog/2006/02/crosmans-mysterious-451-military-45-auto/?srsltid=AfmBOor2SltZ_zmCqRKWQB6s_6blsIs4qA92B4nrDaMQJcznHUvjeNh0
Doc
“You may know nothing about the airgun you have to test, but knowing about the gas it uses will tell you a lot about the gun’s expected performance.”
BB,
This was a great report, very educational; thank you!
That reminds me; I got a call from my daughter-in-law; she wants to do zoom calls with me so I can teach her to shoot. I sent her the links to your series, Teach Me to Shoot, and told her to carefully read through the entire series before we even have our first call. 😉
Blessings to you,
dave
dave,
Let me know how she does. And why she wants to learn.
BB
Yes, Sir, will do! 🙂
These days shooting skills are something all God-fearing, law-abiding citizens should acquire. Hope your daughter follows through with her intent, Dave; suspect she will do well if she sticks to it. Wish FM’s had kept on with her initial interest – she seemed to have natural instincts and had the makings of a good target shooter with a handgun.
B.B. and Readership,
The Crossman Forum (green)…that is long gone…had a great deal of experimenting on CO² powerplants.
Some folks were using a liquid valve system that flashed to gas on the way to the barrel. Folks also used large VOLUME cylinders to keep the liquid CO² as warm as possible thereby lowering the time between same power shots.
Dennis Quackenbush started using CO² powerplants and moved on to PCP when it became apparent that CO² and hunting seasons temperatures were typically not a good match in most of the USA.
Some LINKS to great and more recent history of CO² and hunting:
https://quackenbushairguns.com/CrosmanPistolItems.htm
https://quackenbushairguns.com/shot_pistol.html
https://quackenbushairguns.com/xl.html
I own a number of Crossman 22XX, 2300, and DAQ .2550 PISTOLS as well as the AIRROW Stealth that shoots CO², Nitrogen, Helium, and HPA making it a great testbed to compare the different gases on performance; the Helium is the obvious winner and dry air is a close second, with Nitrogen a distant third, with CO² an obvious 4th even on the hottest day.
shootski
PS: how could i forget my Benjamin Dual Fuel Discovery…smh!
With so many comments to this thread already, I’m not at all sure that my off topic note will even be seen. Anyway, here goes: could you do a step by step blog on making a spring compresser? Unfortunatelly, I don’t have a work bench and will have to make do with a temporary set up on our picnic table out in the gazebo. I’m able to service my TX200 without using a compresser. However, should my HW97K require putting a Vortek kit in it, or doing the necessary work on the HW50s that I’m recieving in pieces, a spring compresser will be required. I’ve tried to do a search of previous Blogs, but have not been successful in finding anything. If my request here is redundant, perhaps you could steer me in the right direction. As always, a big Thank You! Orv.
Orv,
Let me give it some thought.
BB
I second that. Also on that note, what do our friends at Weihrauch, for example, use to assemble their rifles? Anyone ever gone on an airgun factory tour?
Here are a couple of references for your review:
https://www.pyramydair.com/blog/2018/03/spring-doc-spring-compressor-review
https://www.pyramydair.com/blog/2016/09/mainspring-compressor
https://www.pyramydair.com/blog/2006/07/spring-gun-tuning-part-2building-a-mainspring-compressor
(Sorry, the next part of the last blog entry appears to be missing…arg!)
https://www.pyramydair.com/blog/2006/08/spring-gun-tuning-part-9cleaning-and-deburring
(Hey, only parts 2 and 9 of this series seem to be still available!)
Hoppalong Doc,
Maybe Tom could get one and do a Blog….
https://www.pyramydair.com/product/air-venturi-rail-lock-spring-compressor?a=7764
I’m still waiting to hear about his SIG ASP20 gas spring replacement efforts. It won’t stop me my routine exercising of my .177 and .22 caliber SIG ASP20s since that so far seems to be a major method of keeping them running…Ed Shultz seems to have been correct about them needing to be shot regularly.
Read the reviews (with a grain of salt) and see if the LINKED product is right for you.
Best of luck. You got this Doc :^)
shootski
Reply.
Tom already did that.
https://www.pyramydair.com/blog/2017/04/air-venturi-rail-lock-spring-compressor-part-2/
I thought Orv wanted to know how to make one.
BB
B.B.,
Thank you. Even if Orv wants to make his own spring compressor there are always other folks that don’t know about this device. I vaguely remembered it but didn’t remember you had done a blog about it.
“Developed for gas spring guns
This compressor was initially created as a shop tool — not for resale. Tom Gore of Vortek needed a compressor that would work on gas piston and gas spring rifles as well as airguns with conventional coiled steel springs. Gas spring airguns may only need a fraction of an inch of compression to get them together, but because the gas pressure is so high they are very difficult to assemble. So Tom created this unit, which he says makes assembly of a gas spring easy. I guess I need to try it that way.”
I should buy one as a “Schopenhauer Impfung” (vaccination) for my SIG ASP20s. It would make certain that their gas springs behave for a long, long, amount of time ;^)
Thanks again!
shootski