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Education / Training Gamo Extreme CO2 – Part 2

Gamo Extreme CO2 – Part 2

by B.B. Pelletier

Part 1

Today, I’ll test the velocity of the Gamo Extreme CO2. Remember, this is a .22 caliber repeater, and Gamo lists it as a 700 f.p.s. gun. Of course, that velocity represents the fastest they expect it to go, and it will only do that with lightweight pellets.

I installed the 88-gram CO2 cartridge with no problem except the room to grasp the cartridge is small. So, I found myself turning it in small increments. Naturally I put three drops of Crosman Pellgunoil on the spot where the cartridge would bear when screwed in, so the oil would be blown all around the inside of the valve.

To load the 10-shot clip, you first pull the sliding forearm all the way back. Then, a second lever on the right side of the receiver is retracted. The clip can then be picked out of its notch in the right side of the receiver.


The 10-shot clip fits in a notch in the right side of the receiver. Pull the sliding forearm back and pull back the button behind the clip that says PRESS.


The clip is easy to load. An o-ring around the outside keeps all the pellets in place.

The sliding forearm operates this slide-action repeater, or “pump gun,” to use the slang term. The only other gun I have to compare this one to is the .22-caliber Shark from Argentina. That rifle is relatively hard to pump, while this one is quite easy by comparison. You cannot hold the trigger down and work the action, because the mechanism is not designed to work that way. But it’s still a very fast repeater.

Crosman Premiers
Crosman Premiers weigh 14.3 grains in .22 caliber, which is a medium weight for a .22. In the Extreme CO2, they averaged 630 f.p.s. with a high of 650 and a low of 599. The average speed produces a muzzle energy of 12.61 foot-pounds.

The trigger-pull is two-stage, but the start of stage two is quite vague. You really have to feel for the second-stage pause. The one I’m testing varies between 5 lbs., 2 oz., and 5 lbs., 9 oz.


The trigger is two-stage and heavy, at 5.5 lbs. average. The safety is manual.

RWS Hobbys
RWS Hobbys, at 11.9 grains, are the lightest lead pellets available, so I try to use them for the velocity testing of most airguns. In the Extreme CO2 they averaged 655 f.p.s. with a spread from 646 to 667. At the average velocity, they’re churning out 11.34 foot-pounds. We know from experience that light pellets don’t usually produce as much energy as heavier pellets in gas and pneumatic guns. So, I’ll also shoot a heavyweight pellet at the end of this test to demonstrate that pattern.

Gamo Hunters
Gamo Hunter pellets weigh 15.3 grains and are a pure lead pellet, as opposed to the hard alloy Crosman Premier. They averaged 626 f.p.s. in the Extreme CO2 and the spread went from 616 up to 634. At the average speed, they’re cranking out 13.32 foot-pounds at the muzzle.

Super heavyweight pellets
For this test I used some obsolete RWS Ultra Mags I had on hand. They weigh 28 grains and just barely fit in the clip. I could feel them bumping around as I worked the sliding forearm. They averaged 500 f.p.s., with a large spread from 464 to 513. The average speed gives an energy of 15.55 foot-pounds at the muzzle. So, the relationship of weight to efficiency in gas guns has been demonstrated. Not velocity, you understand, just power.

Three times during testing the forearm came off the gun when I slid it forward. I think the cause was that I had one of the dismounting buttons depressed with my hand, but they’re in a natural place for my hands to hold, so I have to guard against doing that.

The bottom line at this point is that the rifle has demonstrated the advertised power. Yes, it didn’t quite get to 700 f.p.s., but with non-lead pellets it would so so quite easily. I know there are those who are watching to see how this rifle stacks up against the Hammerli 850 AirMagnum, so this is your first indication.

author avatar
B.B. Pelletier
Tom Gaylord is known as The Godfather of Airguns™ and has been an airgunner for over a half-century, but it was the Beeman company in the 1970s that awoke a serious interest in airguns. Until then, all he knew were the inexpensive American airguns. Through the pages of the Beeman catalog, he learned about adult airguns for the first time. In 1994, Tom started The Airgun Letter with his wife, Edith. This monthly newsletter was designed to bring serious reports about airguns to the American public. The newsletter and Airgun Revue, a sister magazine about collectible airguns, was published from 1994 until 2002, when Tom started Airgun Illustrated -- the first American newsstand magazine about airguns. Tom worked for three years as technical director at AirForce Airguns, the makers of the Talon, Condor, and Escape precharged air rifles. Today, he writes about airguns and firearms for various publications and websites. He also makes videos, and you'll find short clips embedded in some of his artices on Pyramyd AIR's website. Tom is a consultant to Pyramyd AIR and writes under the name of B.B. Pelletier.

29 thoughts on “Gamo Extreme CO2 – Part 2”

  1. Goodmorning B.B.,

    An interesting rifle, that trombone action to me in theory at least is a great way to go. You didn't mention the temperature when you shot the gun. Did that have any effect on your velocity readings?

    Speaking of velocity, do you think that this gun can be modded to run on HPA?

    Mr B.

  2. Good Morning All,

    Just a little rant.. don't read this.. I'm just dumping stuff..

    Did you clean up your mess from the fireworks? Pisses me off that people think it's fine to litter on the 4th of July!!.. even people who never litter otherwise…
    Our little town is a real mess the next morning..

    Ok thanks, I feel better..


  3. BB,
    What are your impressions on quality and durability? I like the power and repeater factor, but gamo seems to have a thing for plastic.
    Shadow Express Dude

  4. Abstraction is the enemy of the shooter, at least of this shooter.

    When shooting at 50 yds, I can't seem to get a 1 inch group on paper. However, I can hit the butts of shotgun shells most every time (eight out of ten times).

    This would theoretically mean than I could get a 3/4 inch group on paper. Why is it that I seem to have better concentration and handling when shooting at a small plinking target than at a bullseye on paper? is it that I am not really trying to hit the bullseye but instead I am shooting for groups?

    Another example is what happened last week, both with the Whisper and with my brand new Savage Mark II FV. I was aiming at the bullseye of the Gamo paper targets at 50 yds. Of course, all impacts ended in the black around the white bullseye, so I could not see where they were hitting until I walked up to the target. The results really sucked, even though I thought I was being very careful aiming always at the same point within the white bullseye. Then I switched approach. I aimed off the bullseye trying to hit as I would do with a small plinking target. BOOM! 8 out of ten rounds went through the white with the Whisper. Similar results with the rimfire. (There was absolutely no wind that day )

    The games my mind plays with me… Any psychologists wanting to chime in?


  5. ajvenom,

    I agree with what Fused said yesterday about the rust found in a Discovery. He said, "Point is, we don't know what the owner did to that gun."

    However, I will be keeping an eye on my Discovery pistol since I use a hand pump exclusively.


  6. Hey Wayne,

    no problem with fireworks trash here in the "Garbage State" or the "Tax Me State" which is New Jersey. Get caught with a sparkler and you can be arrested!

    I finally watched "Quigley Down Under" last Friday. Sorry, BB but this is a movie that had a poor plot, worse acting, and who the heck hits a target at 900 yards offhand? The best actor in this movie was Alan Rickman, the villain. Sheesh, glad I didn't pay good money to watch this dog!

    Mr. B., my accuracy testing with the 78G and the Gamo Extreme begins tonight.


  7. B.B.

    I'll be interested to see the comparison with the Hammerli 850 which gets good reviews. However, to an extent, it seems like the design is somewhat working at cross-purposes in enabling quick follow-up shots which you can't really use with the CO2 powerplant. It drives me nuts with the 1077 to have to wait 12 seconds or so to regain accuracy. It seems like outside of extremely short-range accuracy/snap-shooting that CO2 is best suited for casual plinking.

    Twotalon, hang in there and best wishes.

    Kevin, redemption is always welcome. 🙂 I'm actually quite apolitical, but I'm as American as the next. Happy belated birthday USA!

    Gustav, I would enthusiastically second B.B.'s recommendation for Savage rifles for long-range accuracy and affordability, especially in the sniper mode. They are putting a lot into their law enforcement line so that you have a lot of variations on the basic 110 action. I got the economy rifle that retailed for under $600 that will shoot .5 MOA for someone who knows what he's doing. There are new models coming out with the Accustock which solve the only criticism of Savage rifles–the cheap stock. There have also been numbers of rave reviews about the flagship law enforcement rifle, the BATV or something like that which is the barreled action in an AR type adjustable stock. It's about $2000.

    For super high-end, you might also take a look at a new rifle I've read about called the Ashbury International Group AIG Assymetric Warrior sniper rifle in .338 Lapua Magnum. It's another bolt-gun with an AR stock (continuing the trend) with a very advanced electro-optical system whatever that is. But one review has this rifle grouping .5 MOA at 1460 yards–9/10 of a mile. No one has dared to mention the price of this thing.

    Wayne, since the the Marauder is so accurate already I don't see how a single-shot conversion is going to change things that much. Interesting that the Crosman FT rifle looks like it might be a reality after all. But my money is still on the Marauder since the accuracy can hardly be improved on, and it's got the barrel shroud.

    In other news, Mike Melick was nice enough to break down my IZH 61 as soon as he received it last Thursday. Preliminary results are puzzling and a little disturbing. There seems to be nothing wrong with the rifle. Spring and piston seal are intact. There's enough lube. I'm glad there aren't a mass of fragments in there, but I would feel better about some clear, definable fix. Mike is cleaning with JB paste now, and we'll see what happens. Like the song says.

    Black is black
    I want my baby back.


  8. BB,

    Did you ever owned a Crosman 622? Mine is still waiting to be restored, but I like the pump idea. What other pellet guns have used the pump design?


  9. B.B.
    I'm really surprised at the 15fpe with the heavy pellets! It'll be interesting to see which pellet is most accurate. Also to see what you say about those funky sights.

    I'm guessing that you would prefer the 2260se to this gun because it's a single loader and build quality, am I correct? Would power be about equal?

  10. Well FRED, I suppose you're one of the few I've seen put it on the Net that they didn't like "Quigley". I've never really offered an opinion on the movie (never saw it "uncut" only via TV, so I don't feel I could rightly give one.
    What I can say is, You paid attention to the plot????

  11. CowBoyStar Dad,

    What model of Anschutz .22 did you shoot in competition? I had a 1407. I sure wish I had it now. The price has increased dramatically.


  12. Fused, I've found that for some reason Gamo Hunter pellets in .22 always delivers a high level of power. Very often springers have higher muzzle energy with lighter pellets, but for some reason the Hunters seem to be a bit of an exception.

  13. I have A RWS 54 with a bushnell elite4200 scope. I put a rws scope stop in front of the front mount and the rear with pin in a hole. I used red lock tight on all mounting points. Still the recoil twisted the mounts apart .I called B- Square and the said they will send me a one piece mount. The mounts look well thought out but their too soft for a magnum air rifle.This is the two piece adjustable b-square mounts.I have another 54 /W beeman Dampa mount that held up over 10 years in 22 cal. This one is 177 cal. I need windage adjustment as this gun shoots off to the side and their is not enough adjustment in the scope /w a fixed mount.

  14. Daniel,

    Your scope stop was in exactly the wrong location. It should have been BEHIND either ring instead of in front of it. The holes are inconsequential, because they are too shallow to work.

    I have mounted scopes on two different Diana 54s with B-Square scope mount and two years later both are still working.

    I can't help you if you won't use what works.


  15. Matt, I wish!!
    Mine was a 1710D. Essentially a top quality sporter. However with diopter sights and a shooting sling it was a killer in the local matches around here (Edmonton, Canada).
    In the late 70's to early 80's Edmonton was definitly not a hotbed of 'real' competition guns. The 1710D and my dad's S&W 41 were about as exotic as you could find.
    But damn, it was accurate.
    CowBoyStar Dad

  16. Matt61,

    I've been out of touch lately due to work obligations. I've read the blog, but barely skimmed and/or missed most reader comments. What happened to your IZH-61?


  17. Thanks AR Tinkerer,

    Hopefully the rust is just a fluke or maybe somebody's spreading rumors to buy Disco's and pumps for cheap……like me lol!!!! if I had a pcp, it would probably be a dico or Marauder with a pump.


    Thanks for the Gamo CO2 extreme reviews. I guess people have knocked the covers off the 850 also. The scope and the trigger seem to better on the 850, but the Gamo seems to develope more power. Will we seek a Gamo Whisper CO2 Extreme someday?

    I guess it be interesting to see how the shooting goes on these two air rifles.


    btw welcome back derrick,

    me too, never hurts to have some extra money or nowadays just a job.

    Happy Shooting Everyone!!!

  18. Daniel,

    Re. the RWS 54, I have found that putting athletic tape over the scope rail before attaching the rings ensures a fit so tight that special equipment or brands are not needed.

    I would like to know if this works for you, too.

    – Dr. G.

  19. E in V,

    plot? what plot?

    what can I say, it's one of my failings, of which I have a few – at least that's what others tell me but what do they know? 🙂

    I've just shot the 78G for accuracy. I found that on a diagonal, I can shoot 33' in the basement so I sort of bench rested the gun and used Meisterkugeln 14 gr .22 wad cutters. Groupings were atrocious, IMO. Best group was 3/4" ctc and nothing in the x ring but I'm going to try another pellet before I go to the Gamo Extreme.

    I haven't gotten the Chrony out to chart velocity but if anyone thinks it'd be nice to know, let me know and I'll do it. Be curious to see what pellet BB found his gun liked when we get the next installment.

  20. Fred,
    Why do you say Quigley shot 900 yards offhand? That was my initial impression of the range, also, but after some tedious calculations and mild conjecture, I found it was very unlikely. The figure 550 yards is thrown about quite often, also, but that seems too short.

    I loved the movie, but all it takes is crazy women and guns to make me happy:).

  21. AR Tinker,

    Thanks for the link… but it didn't work for me.. I'll try it with a little tweeking tomorrow..


    The Field Target rules say you can't use a multishot gun.. so a single shot tray is a must if one wants to use a multishot like the Air Arms s410 or Marauder… and your right about it not changing the accuracy 🙂

    Ashland Air Rifle Range

  22. E in V and BG_Farmer – OK, I stand corrected. The movie contends that Quigley shot a bucket not at 900 yards (that was what was written on the paper that Alan Rickman's character, Matson, opened at the beginning of the movie) but, with BG_F's calculations, was ONLY 550 yards offhand. Folks, I would not be able to see that damn bucket at 550 yards let alone hit it with open sights but that notwithstanding, I have my doubts if Carlos Hathcock could do that consistently, rest his soul.

    Anyhow, E in V and BG-F, I have an offer to make but don't wish to take up the rest of the Blog's space so, send me a message at cyclealleyriders@gmail.com.


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