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Ammo Umarex Fusion CO2 rifle: Part 5

Umarex Fusion CO2 rifle: Part 5

by Tom Gaylord, a.k.a. B.B. Pelletier

Part 1
Part 2
Part 3
Part 4

Umarex Fusion rifle
Umarex Fusion CO2 rifle

Today, we’ll test the Umarex Fusion CO2 rifle at 25 yards. And today was also supposed to be the day I tested how long you have to wait to remove the CO2 cap after exhausting the gas. That’s not going to happn, though; because when I took off the CO2 cap to install 2 fresh CO2 cartridges, I noticed the o-ring was damaged pretty bad. So bad, in fact, that it might not work any longer. I switched it for a common black Buna o-ring of the same size and then charged the gun. At the end of this report, I’ll tell you how that works.

Umarex Fusion rifle damaged o-ring
The original o-ring had these two damaged spots. I thought it might leak, so I replaced it.

JSB Exact RS
When I tested the rifle at 10 meters, the best pellet was the JSB Exact RS dome, so that was the first pellet I tested this time. As I predicted after shimming the rear scope ring, the rifle was hitting too high at 25 yards. I had to drop it about 2-1/2 inches and move it to the right about three-quarters of an inch.

The first 10-shot group I fired measures 0.523 inches between centers. It’s nice and round, also. Remember, I’m using the 4x scope that came with the rifle, so the bullseyes looked pretty small at 25 yards. Also keep in mind that this shooting was done indoors, so wind is not a factor.

Umarex Fusion rifle JSB Exact RS group 1
These 10 JSB Exact RS pellets made a 0.523-inch group at 25 yards.

The first group looked so good through my spotting scope that I shot a second one with the same RS pellets. This time, 9 of the pellets went into 0.455-inches, but one shot opened the group to 0.688 inches. That wild shot was not a called flier; it just went astray.

Umarex Fusion rifle JSB Exact RS group 2

This second group of JSB Exact RS pellets measures 0.688 inches between centers.

H&N Baracuda Match
The second-best pellet at 10 meters was the H&N Baracuda Match, so that was the next pellet I tried. Ten landed in a 0.625-inch group that’s open but fairly round at the same time. Looking through the scope, this group didn’t look very promising; but I see upon inspection that it isn’t much worse than the first 2 groups.

Umarex Fusion rifle HN Baracuda group
Ten H&N Baracuda Match pellets went into 0.625 inches at 25 yards.

Air Arms Falcon
The final pellet of the day was the Air Arms Falcon dome, which is made by JSB. Sometimes, this pellet surprises me with stellar accuracy. This time, 10 pellets made a group that measured 0.56 inches between centers. It’s very close to the first group of JSB Exact RS pellets, which turned out to be the best group of the day.

Umarex Fusion rifle Falcon group 2
Ten Air Arms Falcon pellets went into 0.56 inches. It was the second-best group of the day.

The new o-ring
The new o-ring worked, but there was some leakage when I pierced the cartridges. The gas exhaust screw wasn’t the culprit this time — it was the o-ring that leaked. I suspect I selected a ring that is too thin for the job. When I removed the cap, I saw that this ring had also absorbed the gas and swollen quite large. I took a picture of it 5 minutes after taking it out of the gun and again after 45 minutes, so you can see the dramatic difference as the o-ring outgasses and shrinks back to normal.

Umares Fusion rifle new o-ring after 5 minutes
The o-ring after 5 minutes out of the gun. It’s still swollen with absorbed CO2.

Umares Fusion rifle new o-ring after 45 minutes
The o-ring after 45 minutes out of the gun.

Final evaluation
There’s a lot to like about the Fusion air rifle. It certainly is accurate, and it fully delivers on the promise of quiet operation. There aren’t many other air rifles in this price range that can compete. Even the scope that comes with the rifle seems to be up to the task.

While today’s groups are not stunning, they’re all good.  It’s interesting to note they’re all under three-quarters of an inch and some approach a half inch.

I do think the o-ring that comes with the rifle needs to be changed to something that doesn’t swell. And it would be nice if the trigger was more adjustable. But those are small points. If you’re looking for a fun plinker that’s both quiet and accurate, put this one on your list!

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.

94 thoughts on “Umarex Fusion CO2 rifle: Part 5”

  1. B.B.

    Why did the original o-ring get damaged? Did you have to wait to remove the new o-ring or did it come out right away despite the fact it was swollen?

    As you said, the groups are alright but I was hoping for sub 1/2″. Any chance a better scope could improve the groups?


    • G&G,

      I waited for 2 days after exhausting the gas to remove the cap, so it wasn’t that. The o-ring is made from a material that has a low durometer reading. It is soft and apparently not too tough. I used Pellgunoil heavily every time I replaced the cartridges (3 times) so it didn’t happen from lack of lubrication.

      I don’t know if a better (more powerful) scope would help or not. I think I got all the accuracy the Fusion had to offer. Of course if I continued to shoot groups, there would eventually be one smaller than a half-inch, but it wouldn’t be representative of the rifle. What you see here is what the rifle can do under good conditions.


  2. BB
    The pictures of the o-ring expansion is a eye opener.

    And now I’m wondering if I’m looking at the Co2 reservoir in a wrong way.

    On the Fusion when you put the 2 cartridges in the air reservoir back to back and the cartridges get punctured (on both ends) it fills the reservoir with Co2. Right? So the o-ring has to seal the reservoir to keep the Co2 in.
    And I believe that is how the Fusion works. (correct me if I’m wrong please)

    Now if I take a 2240 and put the end cap on and puncture the cartridge. The end cap only acts as leverage to put pressure against a seal to the pressure valve if I remember right.

    The reservoir were you place the Co2 cartridge in the 2240 is only a chamber to hold the Co2 cartridge. So the end cap does not need a seal. And it works just great as a pressure relief when the cartridge looses its seal to the pressure valve. (the threads allow whats left in the cartridge to release very gently)

    So maybe we I was trying to compare 2 different systems to each other.

    The system in the Steel Storm is more similar to the 2240. When you put each cartridge in the steel storm you have to use the little wing nut tool to tighten the cartridge up to pierce then tighten more to seal it to the magazine cartridge holder(its sealing surface).
    Again a different system then the Fusion.

    So BB you are right. No matter what seal (well maybe I’m going a little too far) you use for the Fusion.

    That seal will have to relieve itself. Maybe different types of material would speed the process. But the shrinkage still will have to happen.

    Maybe no other way around it?

    • Gunfun 1

      I own both the 2240 and the Fusion and I believe you are exactely correct on both counts! I also own several multi cartridge rifles and pistols. All of them work exactely as you say, Two CO2 cartridges have separate tensioners that tighten each cartridge against a thick seal into a piercing device. Also every single CO2 rifle or pistol that i own that has an end cap in a single CO2 cartridge system is used only as a tensioner against the cartridge to a rubber seal, and not to seal the chamber or the system like the Fusion does. On my Fusion neither piercing point has a seal. I looked down the tube as well as at the top piercing point and no seals! So the only thing holding the pressure in is that O-ring. I’ve only used it once after I heard there were problems, so I caught a good video on YouTube about how to load the CO2. I don’t think I would have kept it because I would have wasted so many cartridges in trail and error if it wasn’t for the video. I read the instructions a few times but I still would have been lost if it weren’t for mikeiniowa and BB’s commentary on the function of the valve workings. The instructions turned out to be ok? But the tech info and video is what brought it home for me.

    • GF1,

      Most of what you say is correct, but not the part about the seal needing to expand to seal the gun. That’s not how o-rings do their job in most cases.

      Perhaps I need to write a report on how an o-ring works, to help everyone understand the dynamics of how they seal?


      • BB
        I would like to see a article about how o-rings work.

        Especially with what difference the Co2 makes on the o-ring seal verses what the compressed air in a PCP gun does to the o-ring seal.

        And what the different types of material used in the o-ring seals do. Like those white seals that are usually used in places on the PCP hand pumps in such.

        I think that would be a very informative article. Of course when you find the time. 🙂

    • Now, here’s the real thought…

      How much would it take to convert this beast for bulk-fill CO2… seems to me if you could replace the pressure release screw with a fill-nipple/valve, you could totally drop the use of small cartridges and just take a big tank of CO2 to fill the reservoir.

  3. BB,

    Pretty nice groups, but the seal problem really puts me off. Is there a bulk fill kit or version of this rifle? I think I’d rather fill from a paintball tank once in a while than have to deal with the o-ring.


      • BB
        I like that that idea! As I told dritter in this blog I have 0% knowledge on bulk-fill or pcp’s? Would bulk fill still use CO2? Or a hand pump like a pcp? And how much or what pressures? He explained it pretty well by using a foster fitting but does that foster fitting have a valve built in it so once you alter the fusion valve the air stays in. I realize as I understand it that I would still need that crazy O-ring and the main part of the fusion valve assembly but that with bulk fill I would never have to unscrew that again. I notice that Pyramyd AIR has tons of fittings and adapters, if you or anyone does this mod please share the part #’s and procedure. I know the warranty would be out the window but this would be neat. Or if this doesn’t pan out I hope that Pyramyd sells bulk bags of replacement O-rings so every few CO2 cartridge changes we can replace the bad O-ring. I still like the Fusion! The bolt cocking and the O-ring are my 2 main problems.

  4. If i wait patiently, there will be someone who has bought one of these and has not read this blog. They will be so annoyed with the sealing procedure that they will want to sell it on, hopefully very cheaply to me. LOL

  5. Dear BB,

    As you are completing your report about this .177 rifle powered by CO2, I will make a quite off topic comment. About two weeks ago I was surprised by the extreme character of the difference in the energy delivered by this rifle when changing from light to heavy pellets, I then said that I wanted to make a little experiment. The “experiment” consisted in shooting light (4.7 gr), medium weight (7.9 gr) and heavy (10.5 gr) domed pellets into glycerine soap bars at close distance (about ten inches) with two different low powered .177 rifles: a break-barrel springer Baikal-IZH 38 and a Crosman 1077. I made several shots with each combination pellet-rifle (not too many, I was limited by the number of soap bars I was authorized to destroy at home…) and I calculated the average penetration. Certainly there is a direct relation between energy and penetration, but I am not claiming that this relation is linear. Nevertheless, I give here the results. I take 100% for the maximum penetration achieved with each rifle, so the comparison is within each rifle and not between both rifles. With the Baikal springer I obtained 100% for the 7.9 gr pellets, 88% for the 4.7 gr pellets and 80% for the heavy pellets. Instead, in the case of the Crosman CO2 rifle I obtained 100% for the heavy 10.5 gr pellets, 92% for the 7.9 gr pellets and 80% for the alloy 4.7 gr pellets. These results would change with distance, as lighter pellets would retain less energy after interaction with the air, but only in the case of the springer this could reverse a relation, making things even worse for the alloy pellets. I want to make clear that this “experiment” is not anything that I want to test to be applied in a hunting situation: I would never use these low power nice airguns to shoot anything alive.

    Thanks for your attention!


  6. I hate it when one shot ruins your nice group. I had a few of those last night. With any rifle other than the IZH 61, I would be tempted to make excuses.

    /Dave, yes, the brass is good in principle, but the primer is not, right? You cannot seat a new bullet without detonating the primer. You can’t remove the primer without detonating it. You can soak it in oil for a time to deactivate it and then remove it, but you’re never really sure. It’s easier just to get rid of the brass and primer.

    On a brighter note, there was an article saying gun and ammo sales have decreased for the first time since they went through the roof a couple years ago. IMR 4064 come to papa!


    • Matt,

      Just soak the brass and primer overnight, them press them out as usual. I’ve pressed them out without the soak without donating any of them, so soaking them is probably overkill, but…. Better safe than sorry!


  7. Ah, no brave hearts.. Just take that cap assembly to your favorite machine shop along with a 1/8 male Foster fitting and you go home with a bulk fill adapter. Remove the piercing nose, disassemble the de-gassing assembly, drill and tap the hole and reassemble. Unless of course the degassing shaft was a 1/4-20. Bet the old cap will not cover the FF.
    I bet the results are much larger than 24 grams..

    • Dritter
      I’m very interested in doing what your talking about and I understand most of what your saying as far as the fusion valve assembly. But I have 0% experience about bulk fill? Would that be with CO2 or could you just get a hand pump like a Pcp and at what pressure? I haven’t gotten into pcp’s yet but I know they use foster fittings. And if it’s CO2 how would you know how much to put in? And does the foster fitting have a valve assembly built into it? If you or anybody else has the time I’d love an education on this! Thank’s!

      • Greg
        I am a machinist. I have not done the conversion but I would like to know the results of how many shots you could achieve when using compressed air like a PCP gun.

        But they could of made one little design change that I believe would of helped the cap they have on the gun now. If you look at that diameter that the o-ring seals and follow it down to where the diameter gets smaller where the cross drilled holes are. (looks like about 1/8″holes) They could of made that a tapered seat where the diameter steps down. Then the o-ring would of just been a back-up seal.

        But I would like to see the results of compressed air also.

      • The bulk fill conversion that people have been talking about would be with co2. For two fairly simple reasons: safety and sealing

        As Stephen Archer explained to me when I asked about using HPA in a regular QB 78/79* several years ago… You don’t want to use HPA air in a co2 gun (without extensive modifications) for safety reasons since the pressure difference would be dangerous. Tom has an article on PA where he explains that Co2 operates at about 850-900 PSI. PCPs usually operate at pressures in excess of 2000 PSI. So odds are a co2 gun’s parts aren’t designed to safely handle the sorts of pressures PCP guns deal with. The reason the Discovery, etc… can handle both co2 and HPA is that they are designed for HPA to start with.

        As for sealing… As I think Tom explained a while ago, co2 molecules are fairly large and so the seals don’t need as tight a tolerance as you need with HPA. So its not a guarantee that every co2 gun could seal HPA since it depends on the tolerances the gun is built to. The reason the Discovery works a duel fuel gun is that the tolerances, interior finish, and seals on that gun are designed to deal with HPA (a higher standard than co2 requires).

        *The manufacturers have since developed a regulated PCP version of the QB79. They use a special fill tank to hold 3000 PSI HPA and have a regulator that only releases less than 1100 PSI into the working parts of the gun. In fact there’s a warning on the sales page for that rifle in highlighted, bold, text that specifically states “THE QB79 PCP AIR RIFLE MUST BE USED WITH THE NINJA 13/3000 SHP TANK SUPPLIED WITH IT. USING ANY OTHER HPA TANK THAT DOES NOT REGULATE THE OUTPUT PRESSURE DOWN TO 1100 PSI OR LESS MAY CAUSE FAILURE OF YOUR AIR RIFLE, TOGETHER WITH SIGNIFICANT DANGER OF INJURY, OR DEATH, TO THE OPERATOR AND ANYONE IN THE AREA!!! “. The caps are not mine. They’re on the website selling the QB 79 PCP so that should tell you how seriously the need to reduce the operating pressure in this PCP gun to something similar to co2 pressures is.

        • That is one of the reasons I say LOW PREASURE compressed air.
          Beacuse of safety concerns.

          If the system already runs on 800 psi of Co2. Whats the diffetence if you use LOW PREASURE compressed air with less shots?

          • I’d suspect the number of available shots would be so few that one would tire of refilling the reservoir.

            CO2 exists as a liquid with a gaseous volume above it. It is essentially at the point where, for each molecule that evaporates out of the liquid, another molecule dissolves into the liquid.

            When you fire a shot, the gaseous volume drops in pressure, allowing more liquid CO2 to vaporize bringing the pressure back up to the steady state point.

            CO2 pressure doesn’t really drop until you run out of liquid to vaporize. Steady pressure means a chance for a steady trajectory…

          • As Tom and Wulfraed said, you could run a co2 gun on low-pressure air (at roughly the same pressure as co2), assuming the gun’s tolerances where tight enough that it would hold air. (Given that this is a Chinese-made gun, I’m not sure that they would be. Then again maybe I’m being unfair the people working at the factory in China where this gun is made). And as Tom said the power would go up, for a few shots anyway. The issue is that when you combine the low pressure with the relatively small volume of the co2 reservoir, you’re looking at less than 10 shots. And at that point you might as consider getting a better quality multi-pump like the Benjamin 392/397, especially since it would cost less (especially after the costs of the conversion are factored in) and be better built.

            • J.
              I would say that probably most people understand what you said above in the last few comments.

              But the question was about if the Fusion could be converted to bulk fill Co2 or turned into a PCP gun.
              And to me it seems the answer is yes.
              And yes the bulk fill Co2 would be the way to go with out a doubt. But the (low pressure) compressed air would work on the Fusions current Co2 tune.

              I have many guns. But one of the guns I don’t have is a (low pressure) PCP gun. And yes I have 2 Discovery’s. And I don’t mean 2000psi. I mean 800psi or even lower PCP gun.

              And I would like to have one. The Fusion is a perfect example of a basis to start a platform from.
              The only thing that I see that would need to be changed if I was redesigning this gun to work as a (low pressure) PCP gun is it would need a bigger reservoir to hold more air. And of course a way to Fill the gun. I would use a Foster fitting like the Benjamin’s have.

              So when this subject comes up all the time I guess I should stop beating around the bush and just come out and say.

              Somebody please build a modern day PCP gun that shoots on a (low pressure) 800 psi or lower fill pressure. And I will probably by it. Well depending on where it is made.

              • Gunfun,

                Have you considered using a Hammerli 850 as the basis for a low-pressure PCP conversion? I mention it because I know that has been done successfully before, though its been a while since I saw the California airgun hunters board where they talked about doing it so I don’t remember who did the conversion.


                • J.
                  The H. 850 I guess could be used also. But I’m not interested in converting any of these guns we talked about.

                  I guess what I should say is I would like to see a company make a (low pressure) production PCP gun.

                  The reason behind the thought of the gun I’m talking about. Would be they could sell the gun cheaper.
                  Be a fairly powerful gun. And take less effort to pump the gun up to the 800 psi fill pressure.

                  Well I guess I have thought about putting a lighter spring in the air valve on 1 of my Discovery’s though.

                  You know the plunger that the striker hits and allows air to flow through to the transfer port. And then lighten up the striker spring. I think even with the volume of the existing pressure reservoir you could get numerous fair powered shots out of the Disco at a 800psi compressed air fill.

                  Problem is I think I’m starting to get a bit lazy in my older days.

                  And I think I will just wait and see if they build one. Whats that saying. (Build it. They will come.) 🙂

                  • Unless your reservoir is humongous, I doubt you’d ever get many useful shots from an 800PSI compressed air charge.

                    Consider my Marauder. At it’s optimal point (2600->2500PSI) it is using 10PSI per shot.

                    2600PSI is three times the pressure of your proposed 800PSI gun. Hence, a 10PSI drop in pressure is probably three times as much air as a 10PSI drop in your 800PSI gun… For the same velocity performance, you are probably seeing a 30PSI drop per shot. 3 shots will drop that reservoir to 700PSI, 10 shots probably drop you to under 500PSI (since you’ve likely fallen off the optimal usage curve — the next 10 shots on my marauder are using 12.5PSI per shot, the third 10 17.5PSI each).

                    Maybe if the reservoir were three to four times the displacement, you’d get 10 good shots. Of course, at three times the displacement, you’ll need three times as many strokes with the pump to make the same change in PSI.

  8. B.B.
    I was wondering your feedback on the Hawke Eclipse 4-16×50 the the seller wouldn’t let me upgrade to the Sidewinder tactical. Hawke returned my Eclipse and said nothing was wrong. They said I had the ring mounts too close to the
    elevation/windage adjustment and magnification adjustment. After tightening the rings 16 in/lbs. After each shot the scope would slide between1/64th” to 1/32nd”

    • Stan,

      The quality of any scope has nothing to do with the proclivity to slip in the rings during recoil. If you are using 1-opiece rings, that can allow slippage, because the two rings move together. Two-piece rings can stop some scope slippage.

      Also 4-screw rings caps are best for heavy recoiling airguns. Do you have them?


      • B.B.
        The only mount I have is the RWS lockdown. After calling various sellers almost all recommended converting to weaver rail with two rings. Witch way would be better for me to go? I’m going to center my scope, shoot it through the RWS mount, flip the mount around,shoot again if needed to see which direction I nee to go to correctly mount my scope?? Is that a good plan or am I off the mark again

      • BB
        Maybe you or Loyd could help out with the question about how many shots and if the conversion could work with compressed air on the Fusion.

        Even 10 or 15 shots on a 800 or so psi fill wouldn’t be bad. And even if it only shot at 500 fps. It could still be a fun plinker.

        Not to say it would be something every body would want. But if the idea could work. And some people would be satisfied with the result.

    • Hawaiian Eye,

      you missed it for 2013. It’s typically held September to early October, Friday and Saturday. When I was there this year (9/27 – 28), one of the Elks said that a date had already been reserved for 2014. I haven’t seen this announced yet. Only the Findley, OH show has been announced: FLAG CITY TOYS THAT SHOOT April 12, 2014
      Lighthouse Banquet Facility
      10055 S. R. 224 West
      Findlay, OHIO 45840

      Fred DPRoNJ

  9. With all the leakage issues, parts not assembled correctly, and now o-rings that don’t seem to be very sturdy I’m thinking the chinese made gun isn’t worth the money. If Umarex would go to a factory in another country where they knew what quality was I might think about buying a few Umarex guns. I like the Walther lever action but with it being made in china I suspect it will also be shoddily made.

  10. I had a problem with a slow leak in mine. After a suggestion from someone on GTA (MM) I took out the end screw and ran water through it then used a pipe cleaner to clean the end and the sides out a little it has held Co2 for 4 days.

    My SLOW leak problem was solved with water and a quick brushing with an old pipe cleaner.

    the rifle is very accurate at 10 yards and i was quite happy at 20, though the red dot i have on it made it difficult to be prescise, all 10 shots were smaller than the dot at 20 yards which was .. penny sized i am guessing. I am NOT a great shot, so others would do better.

    Just wanted to update from my previous comment inre leaks

    • Geoffrey,

      What your procedure did was remove some dirt particles that were causing a slow leak. Cleanliness is of paramount importance when working on pressurized airguns.

      If you will now use Pellgunoil every time you pierce a new set of CO2 cartridges, you will probably never again have that problem. The oil helps flush out the dirt — especially when drive by the pressure of the gas.


      • I always use the pelloil, however i got it used so no clue if the seller did and it leaked after 24-36 hours from the day it arrived. Maybe that is why I got it for a song. ;- )

        Thank you very much for the tip though as i dont know THAT much about air rifles and apprecaite your insight.

        I very much appreciate the blogs you put out and have been absoultely happy with all transactions with PA. I tell everyone I know to hit your site if they mention wanting an air gun.

  11. Wulfraed
    You are probably right about the size of the reservoir. But look how small the reservoir is of the Fusion. It only has enough area to hold 2 Small Co2 12 gram cartridges.

    If it was 4 times bigger it would be around the size of a Disco or Mrod.
    And if I remember right when pressure is released it doesn’t now how big the air reservoir is. It only knows how to escape.

    And my Disco will only use 2 pumps from a hand pump per shot. And my Mrod uses about 3 and a half pumps per shot. And that was in my old days of shooting with my hand pump. And I’m glad I don’t hand pump anymore.

    But the thing is I really don’t care about how many pumps it takes to fill the gun.
    What I’m interested in is how many shots I can get at a decent fps with the lowest amount of pressure that is used and released per shot.

    Here is what I would like to get. One shot that uses about 75psi per shot. And I don’t care if I only get 10 shots or so per fill.

    And the next question is what kind of fps would that produce with lets say a 8 grn. Superdome in .177 cal. That’s what I want to know.

    • But remember, CO2 is in an equilibrium — most of it is liquified, with just a bubble at the top in gaseous form. When you fire, you basically drop the pressure of the bubble, until more liquid evaporates to bring the pressure back up to the equilibrium point. That equilibrium point/vapor pressure is around 850PSI (temperature dependent) so long as the cartridge has liquified CO2 in it.

      Compressed air (not liquified) will drop in pressure with each shot.

      Rather than PSI, I’m going to shift to bar…

      800PSI => 55bar
      2600PSI => 180bar
      15PSI => 1bar

      A shot that sucks 15PSI is drawing about 0.6% of the 2600PSI reservoir. It draws nearly 2% of an 800PSI reservoir. If my mental exertions aren’t totally bogus, that implies the 800PSI reservoir needs to be four times the displacement of the 2600PSI reservoir in order for both to sustain a 15PSI drop in pressure per shot.

      Maybe the velocity end is the better starting point… CO2 at around 800PSI with 7.7gr Superdome from a CP99 pistol: about 330fps, 1.8ft-lbs…

      My Daisy 717 with 8.3gr Meisterkugeln Rifle beats that at 375fps (and the 953 reaches 450fps). Unfortunately, I don’t know the length of stroke and the volume of the reservoir on those single-strokes. Let’s say it starts at 6 inches…

      8inches = atmospheric pressure (15psi absolute, 0psi relative)
      4inches = 2X
      2inches = 4X
      1inches = 8X
      0.5inches = 16X
      0.25 = 32X
      0.125 = 64X (probably a viable condition, given the velocities — 960PSI)

      Hmmm, I’m not sure where I was going with that… Other than maybe that it took a tube 8″x1.5″ worth of air, compressed to 1/64s the length, to power ONE low-speed shot.

      I’ll give up — let an actual pneumatic engineer step in…

      • Wulfraed
        I think I know what you were trying to say. And I believe 100% that bulk fill Co2 would be the best choice over trying to do the low pressure compressed air.

        But now maybe I think I will try the low pressure fill on my Disco to see. Like I said before. Take the air valve out and put a lighter spring in it. I already have a adjustable striker spring and end cap from a (if I remember right) 2300S pistol.

        Not to prove something. But it has been in my head from one of the articles BB did I think about vintage air rifles if I remember right. He talked about a air gun that used I think a 600psi compressed air fill.
        That’s what I want to accomplish. At least if I try it on the Disco it will teach me something about what would need changed to make it work. Will see if I can come up with some spare time.

        • How vintage was it…

          Many of the really old air guns had rather large copper flasks hanging under them as the reservoir. Probably challenging the AirForce tanks for raw displacement (but not pressure)…

          Or look at some of the pump-up type “super soakers”…

          • I didn’t see your post about the vintage airgun yet when I posted the results of the Disco.

            But I really cant remember if BB showed a picture of the 600psi gun. But I’m sure it had to have something like you described.

      • Wulfraed
        I posted here so you could see the results I got with my Disco.

        I was going out to my brothers today to show him the Monsoon and shoot a bit so I grabbed the Disco and some .177 cal. Superdomes also and the chrony.

        Got some results. Not great but not bad. And I didn’t touch anything on the disco and left it sighted at 50 yrds.
        We were shooting at 50 yrds. today also.

        I filled the gun to 800psi and chronyed the gun down to 400psi. 570fps on the first shot and 410fps on the 12th shot.
        Then filled back to 800psi and shot 12 shots at the 50 yard target. I didn’t resight the gun I just let it hit low (1 mil dot low) and on the 12th shot it was about (2 mil dots low).

        The shots were pretty consistent but you could see the POI dropping with each shot. I would say that 7 shots were probably usable shots. That was about a half mil dot change on those 7 shots.

        So I guess it would make no sense for a company to design a gun that would have those characteristics. But it was a fun test.

        • Now imagine the drop off if one had converted this CO2 model, with its /small/ reservoir for 800PSI air (or even 1000PSI). You might get three usable plinking shots before having to refill. And you are getting performance somewhere between a single stroke Pneumatic (Daisy 953/853/etc.) and a multi-stroke model.

          If you need to pump it up after three shots, you break a rhythm — might as well take a third the strokes between each shot…

          • Wulfraed
            Yep I do see what you mean. And I believe that’s what you were trying to explain above when you said it would take a air chamber 8 inches long by a 1.5 inch diameter for one shot.

            Alot of the PCP guns now days have the 2 big air bottles that resemble the AirForce guns type of bottle. And they place one in front of the receiver and another one in place of the stock and butt of the gun like the AirForce guns.

            Maybe it would take something like that and a more precise way to control the air usage like a regulator Incorporated into the system and maybe electronics to control the flow also.

            Then maybe a low pressure PCP gun could live. But it wouldn’t be a very cheap gun that’s for sure.
            Anyway, good conversation.

          • Wulfraed
            You know what I just thought of.

            I wonder how many shots you would get if you bulk filled the Fusion with Co2 with its same reservoir.

            Do you get more shots when you use the 2 small cartridges?
            Or do you get more shots or less shots with the bulk fill because it has the cartridges removed?
            Or do you get the same amount of shots either way?

            • I’d expect a bulk fill conversion to get a few more shots… One would have to drill open the end enough to fill with water (to find out the displacement of the actual cartridge) and compare that to the displacement of the reservoir without cartridges. At the least, there should be two or three shots for the CO2 that takes up the space where the cartridges abut

              ……^ added space for CO2

              • I dont have a Fusion so I cant test that.
                Maybe if somebody does decide to try a Co2 bulk fill conversion of the Fusion they can post the result.

                But I agree with what you said Wulraed. I think a few more shots will be posable with the conversion.

  12. I have been testing pellets for FPS/FPE. I have shot pellets from 7g to 13.43 and have found that my fusion shoots the JSB jumbo 13.43’s at 590fps for just a tad over 10FPE.

    Shooting the lighter pellets the FPE drops a quite a bit on FPE, nearly 4 FPE less.

    IF you are not happy with the FPE yours is getting, try the JSB exact monsters at 13.43.

  13. Gunfun1 – unfortunately i have only been able to shoot in my basement and 5 meters is all i can get.

    shoots very well at that range, though i would expect everything to shoto well at that range. ;- )

    i have a red dot on it, so the dot is larger than my groups which usually overlap each other, or darn close. with a scope i am certain it would nearly stack them.

    • GK
      Me and the kids shoot a 2300S with a red dot on it in the garage at about 10 yards.

      And I have used the monsters and they did good with the 2300.

      Try them outside if you get a chance. The 2300 is pretty good to 25 yards with them.

  14. BB
    You know what. I think we got caught up on how the end cap worked and other things.

    And I looked back. But I don’t think you mentioned how many shots you got from the 2 full Co2 cartridges did you?

      • Tom,
        I have a Crosman 1077 that does not shoot every time the trigger is pulled. When the trigger is pulled again, the pellet cylinder advances and fires normally but leaves a pellet in the cylinder. Sometimes it will leave 2 or 3 pellets in a cylinder. It sounds like the hammer does not fall and release the CO2.
        How can I correct this problem?

      • Tom,
        I may have put this reply in the wrong place before.
        I have a Crosman 1077 that does not shoot every time the trigger is pulled. When the trigger is pulled again, the pellet cylinder advances and fires normally but leaves a pellet in the cylinder. Sometimes it will leave 2 or 3 pellets in a cylinder. It sounds like the hammer does not fall and release the CO2.
        How can I correct this problem?

  15. Has Umarex corrected the o-ring problem?
    If not, where can I buy good replacement o-rings?
    I ordered a Umarex Fusion from Pyramyd AIR today.
    Do you have any information more recent than December 2013?

  16. I LOVE this Uramax Fusion pellet gun.
    It is VERY accurate and quiet.
    It shoots 0.30 inch 10 shot groups at 18 yards inside with its favorite pellets, JSB Exact RS dome 7.33 grain pellets and a 20x scope.
    Velocity with 7.33 grain pellets is 708 fps at 75 degrees F.
    It gets 55 good shots with 2 CO2 cylinders at 75 degrees F and shooting slowly.

  17. To get new o-rings from Umarex call (479) 646-4210 ext. 507 Mon-Fri 8am-5pm CST and they will send you 2 more o-rings free in 4 or 5 days.
    Below are my shooting results:
    6-26-2014 This rifle shoots real good. I like it. I sighted it in with JSB RS 7.33 gr.
    708 fps JSB RS 7.33 gr, 5 shots=0.30”, 5 shots=0.35”, 10 shots=.050”, 10 shots= 0.60, 9=0.50+1=0.80”
    715 fps RWS Meisterkugen 7.0 gr, 10 shots=.060”, 10 shots=0.65”
    652 fps RWS Supermag 9.3 gr, 10 shots=0.70
    644 fps JSB Heavy 10.34 gr, 9 shots=0.55”+1=1.05”
    694 fps RWS Basic 7.0 gr, 9 sahots=0.60” +1=1.00
    All the above groups were in about the same location.
    Crosman brown box = 0.90” but it was at a different location than the others
    Crosman Premier HP = 1.00” but it was at a different location than the others
    6-27-2014 This gun shot best again today with the JSB RS 7.33 gr.
    6-29-2014 This gun put 10 shots of JSB RS 7.33 gr in the same hole at 18 yards inside. The JSB 8.44 gr did almost as good. The RWS Basic 7.0 gr and the RWS Meisterkuglen 7.0 gr did not do as good. This gun is most accurate with the JSB RS 7.33 gr and I ordered 4 more tins = 2,000 pellets.
    JSB RS 7.33 gr = 10 shots at 0.27”
    JSB 8.44 gr = 10 shots at 0.28”
    RWS Basic 7.0 gr = 10 shots at 0.95”
    RWS Meister 7.0 gr = 0.73”
    7-14-2014 shooting 10 shot groups at 18 yards inside with 3-9×40 scope.
    JSB RS 7.33 gr = 0.40”
    RWS R10 7.0 gr = 0.40”
    RWS R10 7.0 gr = 0.72”

  18. My boss gave me an Umarex Fusion for my retirement gift. Very nice pellet gun. The gun is pellet-picky. Thank you for the lead on the JSB 7.33 gr. I have tried a number of pellets (H&N Field Trophy 8.64 gr & 8.49 gr, and numerous Crosman and Gamo pellets): the JSB Exacts are definitely the best in my Fusion.

    My target range is outside, so wind is a factor. At 10 meters I am shooting 1/4″ patterns with both the 7.33 gr and 8.44 gr JSB Exacts. At 25 yrds, the 7.33 gr Exacts are opening up to 1 inch patterns, while the 8.44 gr Exacts are holding to 1/2′ to 3/4″ patterns, With the 8.44 gr Exacts, I am getting under 1″ patterns at 30 yrds. Look out HOSP!

    The scope is OK for up to 20 yrds, but I think the gun would benefit from a magnification of 8X at 25 and 30 yrds.

  19. I missed the boat on this one. Wish I could find one out there. As you stated, not much to pick from in the CO2 rifle category. I don’t like the Fusion 2 with no single tray option/cruddy magazines and all of the issues with it, seems they took a big step back from the original. Thanks for the review on both BB. I will just have to keep looking for one on the used market.

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