Tuning Air javilin upgrade.

[allgooddays]

Hi guys my first post here.

I would like to share mods to HPA conversion of the air javelin.

I've looked on you tube and it seems that most the mods don't really increase power as much as expected.

I've finished my mods and performance is better than the javelin pro.
Even on co2 you can get 350 plus feet per second .
Here is my first chronograph of the modified air javilin.
13 shots.
Low 427
High 447
Std deviation 7
72 ftpd average.

I'm using the cricket z valve set to 1100 psi.
I shot from 3 bar to 2 bar and did 18 shots.
5 not on radar.
It still has at least another 18 shots but it was cold and windy and I didn't dress properly.
Mods.
New brass bolt.
Relieved hammer adjust screw so it doesn't bind at half adjustment.
Add new hammer spring from umarex hpa conversion kit.
Take out co2 piercing point to fill plenum quicker and cooler.
Here is the two things I've seen no one do and make the biggest difference.
At the poppet the plastic molding goes around the poppet.
It restricts it to only open about half way.
If you pump add full hammer spring tension you can feel the hammer slam the plastic wall.

Remove this hammer stop and even with co2 its a major improvement.
Once the stop is removed you have to widen the length of the bolt opening as well to add for the extra hammer travel.
If not the hammer hits the cooking pin inside the gun.

I've also done all the other mods I can think off polished things up.
But the one game changer is urestricting the poppet.
I just wanted to share that as I've not seen it elsewhere.

And a question for anyone who might have a pro or be able to help.

The pro says it's regulated to 1500psi.
The arrows are the same as the regular javelin rated for 1,200 psi.

I'm running at 1100 psi now.
Does that mean I can pump up my gun to 1500 psi safely with these arrows?

Thanks for any replies.
Cheers

 

[MadCowCrazy2]

All I know about CO2 to HPA is that Umarex usa sells a adapter for $53.

UMAREX AIRJAVELIN HPA ADAPTER

buy UMAREX AIRJAVELIN HPA ADAPTER online

www.umarexusa.com

I've been thinking about buying it as I own the CO2 version.
I can't offer much help but as long as you are using aluminium bolts I wouldn't be too worried about the PSI. Carbon and especially fiberglass might explode.

 

[allgooddays]

I picked up the adapter but so far have only used the new hammer spring that came with it.
I picked up a cricket z regulator and modified it to 88 gram threading.

If you remove the poppet restriction and adjust your stock hammer spring half way.
I got 362 fps and 49.7 ftpnds.
If you go over half hammer spring you actually drop because it releases too much co2 and gets too cold too fast.

Here is the gun with the z valve.

And a screen shot of co2 #s after mod .
I started at 0 Hammer spring and at shot 4 was at half way . By full hammer it was down to the 300 range again backed it off and numbers rose again.

As far as the arrows maybe I'm allready pushing it a little as I'm getting 70 fps more than the pro.
And hitting with 70 plus ftp.

 

[allgooddays]

Here is the molding I removed

 

[allgooddays]

Correction to my first post in regards to air pressure.
I didn't pay good attention to my new regulator.
I assumed the outlet side was in psi like my other pcp rifle.
Looking again it's mpa.
So I was shooting at 1660 psi .
Looks like the arrows survived but I'm going to back things down to 1450ish try to keep it shooting at least 400 fps.

Peace out.