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Big Game Hunting Umarex Air Javelin airbow: Part 4

Umarex Air Javelin airbow: Part 4

by Tom Gaylord
Writing as B.B. Pelletier

Umarex Air JavelinThe Air Javelin from Umarex.

Part 1
Part 2
Part 3

This report covers:

  • More to test
  • What are the holes for?
  • Remove the old 88-gram cartridge
  • Lots of gas!
  • Install the adaptor
  • Cock the gun!
  • Don’t do as BB does!
  • Adjust the dot sight up
  • Discussion
  • Summary

Today I shoot the Umarex Air Javelin with a dot sight optic. My UTG Reflex Micro  Dot was mounted elsewhere so I mounted a Tasco Pro Point red dot sight. 

Air Javelin dot sight
The Air Javelin accepted the Tasco Pro Point without a problem.

More to test

I didn’t tell you this but I asked Umarex to send me a 12-gram CO2 adapter so I could test the AJ with 12-gram cartridges. Some readers had asked about that possibility and since Pyramyd AIR doesn’t carry the adapter, I went straight to Umarex.

Air Javelin 12-gram adapter
Several Umarex airguns including the Air Javelin use this adapter that switches the power source from 88/90-gram CO2 cartridges to 12-gram cartridges.

Let’s look at how it works. One end has an end cap that unscrews to accept the two 12-gram cartridges. The other end is treaded to screw into whatever airgun you install it on.

Air Javelin adapter description
The adapter has an end cap (arrow) that comes off to insert the CO2 cartridges, and threads on the other end to screw into the airgun. The holes are for moving the end cap when pressure holds it tight.

The two cartridges go into the adapter nose to nose. The piercing end of the first cartridge goes in first and the piercing end (small flat end) of the second cartridge is left up at the top, where the pin in the cap can pierce it. There is a spring-loaded winding tab on the cap. The spring holds the tab flat against the cap until you need it.

Air Javelin adapter cap off
The adapter cap has been unscrewed.

No directions for use came with the adaptor but it is pretty easy to figure out. I unscrewed the end cap piercing screw as far as it would go before dropping two cartridges inside. And I dropped in 5 drops of Crosman Pellgunoil before inserting the first cartridge. Then I put more Pellgunoil on the tip of the second cartridge.

Air Javelin cap screw
Here you see the cap screw (bottom) unscrewed as far as it will go.

What are the holes for?

If you ask what the holes in the sides of the end cap are for you haven’t yet encountered a gas gun with so much pressure that it wouldn’t let go of the end cap. This used to be a real problem in the 1950s and ’60s when improper o-ring material would swell from the gas and no let go of the end cap for hours after the gun was empty. With modern materials there is no more problem, unless the gas pressure inside the adapter is still high. This is not a large problem; it’s more of a convenience.

As you can see, I unscrew the piercing screw on the end cap as far as it will go, then screw the end cap down as far as it will go. Now I pick up the spring-loaded tab and start screwing the piercing screw in. That one screw is piercing both cartridges. It pushes the bottom cartridge down on the internal piercing pin inside the adapter as well as screwing in the piercing pin in the end cap. So I run it in as far as it will go. I heard no gas escape when I did this, but just to make certain the piercing pins were out of the way of the gas, I unscrewed the tab about a turn.

Remove the old 88-gram cartridge

Before the adaptor could be installed I first had to remove the previous 88-gram CO2 cartridge that was in the AJ. I didn’t know for sure but I calculated there were around 20 shots on it. We learned in Part 1 that the AJ has up to 30 good shots on one 88-gram cartridge. The last shots will send arrows out at just under 200 f.p.s. while the first shots have them going over 300 f.p.s. I will have more to tell you and show you later in this report, but for now you need to know that I was removing a cartridge that had a good 10 shots remaining inside. I had to do it to get a shot count from the two 12-gram CO2 cartridges in the adapter I’m about to install.

Lots of gas!

I will say this. Once you slowly unscrew the CO2 cartridge it comes to a point when the remaining gas is no longer sealed and starts hissing out. That lasted a long time — several minutes at least. I also dry-fired the AJ about 10 times as it was loosing gas to speed up the process. In the end the last gas hissed out and the old cartridge could be removed. The gun was now ready for the adapter.

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Install the adaptor

The adaptor just screws into the gun where the CO2 tank was. Remember I put Pellgunoil inside when the cartridges were pierced, so that gets blown into the AJ to get on all the internal seals. BUT…!

Cock the gun!

Umarex tells you not to cock the gun when installing a new cartridge and I expect they also mean this adaptor. That is obviously a safety issue. But the adaptor holds two 12-gram cartridges that have limited gas. So I screwed the adaptor in, and when the hissing began I cocked the AJ and stopped it instantly.

Air Javelin adapter in
The adaptor fits in the AJ just like an 88-gram CO2 cartridge. This photo was very important later in the test!

Don’t do as BB does!

This is an object lesson. Some of you think I am modest, but the truth is — I am often that bad example your mother warned you not to follow! I set up the target bag in my back yard about 10 meters from the shooting bench. Yes that’s pretty far but I hadn’t shot the AJ in two months and my last recollection was one of great accuracy. It really was accurate last time — what could go wrong? I held the red dot in the center of the target that was taped to the bag and fired the first arrow. But I couldn’t tell where it went. It wasn’t anywhere on the bag! Oh, oh!

I looked in the grass all around and under the bag for signs of the arrow and then in the wooden fence between my property and my neighbors. Nothing. So I dragged the bag back to 5 meters and shot again. This is where I should have placed the bag to begin with.

Adjust the dot sight up

This time the arrow hit the bag, just below the bottom of the target paper. My previous shot had been taken at twice the distance, so the lost arrow is definitely somewhere in my lawn at something less than 10 meters. I searched for another 10 minutes for that first arrow with no luck. Umarex had only sent me three arrows with the AJ, and now I was down to just two. I adjusted the elevation up considerably and shot again.

Shot three hit a half-inch or less from shot two. It was on the bag but still below the target paper. From the looks of it (it was on an angle in the bag), it may well have hit the back of the second arrow— something I would discover in a little bit. Now I knew I was on the target so I cranked in a whole lot more elevation and moved the bag out to 15 meters.

Then I let fly with shot number four. This time the arrow hit the bottom of the 6-ring, almost touching the bullseye at 6 o’clock. Wow! I pulled the arrow out and moved the target bag out to 20 meters.

That shot had looked so good that I fired my second shot (number five on the CO2 adaptor). It hit the target about 3/4-inches below the last one. I needed to watch out or I would Robin Hood my two remaining arrows.

The last test in Part 3 demonstrated that the AJ is very accurate at this distance, so I felt confident it would not be a problem. However — remember that arrow that may have been hit in the back? I knew that I would nail the target in line with the center of the target and with luck I’d be inside the bull. No such luck! This time I heard a sickening sound of the arrow hitting the fence behind the bag. I have never missed the bag before this shot and was surprised I missed it this time. I found the arrow that had gone 4 feet wide to the left and was halfway through the fence.

When I pulled that arrow out of the fence I examined it to see why it had gone so wide. Right away I saw it. The end of the arrow is blown out on one side. I think I did hit the back of this arrow earlier and now I was rewarded with a wild shot. When I enlarged the pictures of all three arrows that was taken before the test started I saw that none were damaged this way. That is what I meant by that earlier picture being so fortuitous.

Air Javelin arrow end
The end of the AJ arrow that went so wide at 20 yards was broken out on one side — causing the arrow to veer to the side as it came off the end of the air tube. This arrow was probably hit in the rear on shot number three.

Air Javelin arrows
I enhanced this earlier photo to show there was no damage to any of the three arrows at the start of this test.

For safety’s sake I moved the target bag back to 15 meters and fired my one remaining arrow three more times — shots 7, 8 and 9. Shot 7 hit the target at the bottom center of the largest ring in the white. I had to pull the arrow to shoot shot 8 and it hit the target about 3/4-inches below and to the right of shot 7. On this shot I noticed a lot of time between the shot and the arrow hitting the bag.

Air Javelin arrows shot 8
Shot 8 at 15 meters hit below and to the right of shot 7. I could hear that this arrow was slower.

I pulled the arrow and fired one more time. This time there was a definite slowing of the arrow and it hit at the bottom of the paper, a little more than an inch below shot 8.

Air Javelin arrows shot 9
Shot 9 hit the target a little more than an inch below shot 8.


Based on this test I can say that two 12-gram CO2 cartridges give you about 8 good shots. They are not all the same speed, but I believe they all fall within the velocity spread of the 30 good shots you get from an 88-gram cartridge. Analyzing the costs tells me you get 8 good shots for about $1.00 with two 12-gram cartridges, and 30 good shots for about $8.00 with one 88-gram cartridge. The advantage of the adapter is shots that cost less. The advantage of the 88-gram cartridge is a lot more shots per cartridge. The velocity of the shots is the same because CO2 varies its pressure due to temperature. Volume is not a factor in pressure.There is no easy way to increase or decrease that pressure — certainly not one that’s available to the field.

The second thing I would tell you is to always examine your arrows just before loading them. I didn’t and only through a fortunate photograph was I able to determine that an arrow had been damaged during this test. A damaged arrow flies erratically and is too risky to shoot.

One last comment is that I need to jack up the rear of the dot sight for the next test. I had to apply too much elevation to get the arrows near to the aim point.


I’m still very impressed by the Air Javelin. Even with the challenges of today’s test, which in retrospect were all mine, the AJ held its own. When it is given half a chance it places its arrows close together at the distances I have been testing.

The CO2 adapter performs as well as many expected. I was surprised by the number of good shots we got in today’s test. And it is very easy to set up and use.

Hopefully we will see the AJ at least once more, and this time with more arrows and no sighting problems.

44 thoughts on “Umarex Air Javelin airbow: Part 4”

  1. B.B.,

    You could possibly cut off the end of the damaged arrow with a rotary tool cut off disc keeping it wet all the while to minimize the danger of the carbon dust. Then you can re fletch the arrow for use again. I believe this was made by Umarex with the German market with its stringent weapon laws in mind so converting this to PCP using pressure higher than CO2 is probably going to break a safety feature hidden inside to prevent such.


    • Siraniko,

      the funny thing is that German law defines “shooting” as “driving a projectile through a barrel”. Thus, arrow guns like this are basically not even considered to be “shooting” at all and are categorised as either a crossbow (not regulated by law) or a toy (Joerg Sprave has several videos on this on YouTube).

      So, shooting a pellet at over 7.5 joules –> strictly forbidden without a permit

      Shooting an arrow at 1000 joules –> legal toy for toddlers

      That makes a lot of sense, doesn’t it?

      Kind regards,

        • BB,

          agreed. It should be handled with the same care as any other gun or crossbow.

          But legally, it’s not classified. The BKA (federal criminal police office) had to admit this themselves (grudgingly, I assume).


          I have no use for an arrow gun anyway. They wouldn’t be very useful on my little indoor 10m range.

          But maybe the reasonable solution would be to at least allow airguns with up to 16 joules (so shooting field target at higher distances is less of a hassle). Yes, these guns are dangerous and can be abused. So is a hammer, a chainsaw, a kitchen knife and many other things that are legal to own.

          On the other hand, I wonder if that would mean the 7.5 joule guns (and springs) would disappear entirely. That wouldn’t be the greatest thing either as we would lose the quiet and easy to cock guns with moderate recoil for indoor use.

          Kind regards,

      • Similar to the law here that says a 100 ftlb 22LR is dangerous, and you have to register to own one, but an 800 ftlb Airforce Texan, ? No fire, so it’s not a ‘FIRE’arm, you could buy one online and have it shipped right to your toddlers door!
        But I think we in the airgun community are making the most of the opportunity, after all, how would we like it if we were like our neighbors to the north, restricted to less than 500 fps?

    • Siraniko,

      Usually the Ninja bottle has a regulator on it to reduce the pressure to the equivalent of CO2. This is what is used to convert the Sig Saur airguns over.

  2. B.B.

    When comparing the cost of an 88 grams cartridge with 2 12 grain cartridges you need to include the cost of new arrows! How much do arrows cost? Can they be made “Robin Hood” proof? 8 shots is not very many…


    • GF1,

      That really is a common occurrence with arrows. Quite often it will “slide” along the ground at the base of the grass and be pretty well hidden from view. Now, where BB is they probably have sandy soil and an arrow really does not have much trouble submerging under the surface of the ground. It is probably not very deep, but is a real bear to find.

      • RR
        Yep my daughters shoot bow and arrow. We have grassy conditions here. Definitely spent some time looking for arrows that slid under the grass. We painted their arrows florescent orange to help see them just incase that happens.

        But what I was talking about is BB mentioned the arrow might of went through the crack in the fence. You never know what could be on the other side you know what I mean.

          • B.B.

            Aluminum arrows are easy, but carbon fiber is not. You are looking for the tip. A combination of ferrous/non-ferrous metals . There will be a lot of phase cancellation. Good luck.


          • BB
            Oh ok you thought the fence between your property and your neighbors would of stopped the arrow if it wasn’t in the grass.

            I just pictured the arrow going between the spaces between the boards.

            Them arrows will sneak right through something before you know it.

            Thinking about that. I wonder how many yards the arrow could go at that velocity and weight. Kind of like if you did a artillery type shot if you had a big area.

            You know some boxes that air guns come in give caution that a pellet can go 500 yards. And I’m talking .177 and .22 caliber.

            That’s a test I would like to see with some air guns or the arrow gun. Not so much looking for a accuracy. But just to see how far they could go.

  3. BB,

    I am with Edw and GF1 in that I would like to see what this will do with HPA. CO2 is so old school. Not really, but to be able to fill it with a hand pump would be nice. I suppose they will bring out that option next year. Also, target shooters will be able to spend more time shooting than changing out capsules. I am certain that would grow pretty old, pretty quick.

    Mike Reames had an adapter for his airguns that held one CO2 capsule. If my rememberer is working right today, you could change out capsules pretty quick.

    • There is a review of this that noted the Ninja bottle does not fit. It is due to the bottle being longer and wider than the CO2 cartridge it would replace. It would need an angle adapter or a tether hose.

    • RR
      I have 2 guns that was originally designed to run on 88 gram bottles. One being the Sig MPX that screws into a adapter and right into the back of the gun. Then I have my Big Bear 1000 that I used adapters to tether the bottle by a short braided hose and is attached to the gun underneath on the weaver picatiny rail by a scope ring.

      So yep there is ways to do it for sure. Right now I have a total of 5 guns that use the 13 cubic inch regulated bottles. I love the guns on the regulated bottles.

  4. A cheap metal detector is all you need to find the missing arrow. It’ll pay for itself after you find three arrows. Also you might want to use a 5 bull target to help with the Robin Hood problem. I’m guessing if you try to shorten the damaged arrow, it will be too short to seat fully over the “barrel”. And lastly I would wrap the tail of the arrow with the best carbon fiber tape (if there is such a thing) I could find. Just to keep from blowing out the rear of the arrow either from Robin Hoods or the stress of shooting repeatedly.

  5. Greetings all!

    I’d like to offer a correction on the holes on that adapter. They’re to allow excess co2 to escape. If you have co2 left in the adapter when you’re done shooting, you can unscrew the black tab cap screw. When you do, the excess co2 will be vented out the holes, and the converter will be inert. You’ll then be able to unscrew the cap screw and remove or change out the carts.

    I’ve had and used that adapter for years! I was always curious why Umarex wouldn’t bring them to the US. They’re incredibly handy.

    • NTOG,


      I wonder if the thread on the gun end of the adaptor has the SAFETY blowdown notch/port in the thread or if it is in the reciever? Or do they expect owners to have some sense… ;^)


      • Yep, it has notched threads there too. If you slowly unscrew the pressurized adapter, you’ll hit that spot where the gun’s probe is holding the adapter’s valve a touch open, and you can dump gas that way too.

        As to the user having sense, that might just be why they didn’t import that adapter for a long time 😉

  6. B.B.,
    I happen to think that tests like this one, where things don’t go exactly as planned, make for some of your most informative reports; thank you. =>
    Keep up the great work,

  7. B.B.

    I’ve used these Umarex 2 x 12 g adapters on various rifles for a few years now. The main thing I look for when loading CO2 is the momentary “chill effect” as the CO2 cartridges are pierced. When I feel the chill in the adapter, I know the CO2 were pierced.

    • There are times, like using the Umarex 1894 to just shoot a couple of magazines, I’d use one fresh cart with an empty one in the adapter. If memory serves, that was enough gas for 4 magazines. Loading that way, only one end of the adapter gets chilled. When using two fresh carts, checking that both ends get that quick chill is a good way to make sure both carts have been pierced.

  8. I have found that the easiest way to find an arrow lost in the grass is to spray the area down with gasoline, stand back and toss a flaming object into the center of the gas sprayed area. You should be able to find your arrow in just a few minutes. Unfortunately this method tends to generate a lot of heat which arrows are not very fond of.

    “I love the smell of napalm in the morning.”

    • Cuts down on how much yard you get to (in my case, have to) mow. I bought the rider for my wife who LOVES to mow until it gets into the high 50’s. Then it’s my job.

  9. If you are only getting 8 shots, check and make sure you pierced both cartridges. You can feel each one pierce at different times. I made this mistake at first and almost threw out 4 good cartridges that were dented but not pierced. With both pierced you should get 12 good shots before all the c02 is vaporized, then there are 2 weak shots before the gun degasses the rest. I use a new one on bottom and old one on top if I just want a few shots. I see there is a 50 grain broadhead now ( blood bug) available which is the same weight as the field points. The arrows are fragile, I hit the plastic leg of my deer target and broke one. If you hit something hard, check for arrow damage before using it again.
    Not sure what I will use this for, airbows not allowed for hunting in NY, but it is fun. Have between 175 and 200 through mine already. Have already learned when to begin aiming higher to compensate for pressure loss.

  10. RidgeRunner,

    Be careful what you wish for! I to thought that way for awhile but found out quickly that the first things to grow back are not trees. If you like pokeberry,multiflower rose, and greenbriar go for it. Besides that, remember those trees you let grow 15 or 20 years ago, they are now big enough to hit your house if they come down in a wind or ice storm.

    My advice to you will be to keep that string trimmer in good running order and keep lots of sharp chainsaw chains on hand.

    Just some food for thought for this evening.


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