Hatsan Hatsan Jet, the air gun I will never own

[DobrinFX]

Yes I did
After assembled it back started filling the tanks but it's leaking slowly and uses way too much air when fires. the O-ring is completely missing. The part number is 2313. I am trying to find what size it is.

From my search that O-ring is1/8" size. Will give it a try

Yes I did
After assembled it back started filling the tanks but it's leaking slowly and uses way too much air when fires. the O-ring is completely missing. The part number is 2313. I am trying to find what size it is.

 

[EdinGa]

From my search that O-ring is1/8" size. Will give it a try

I'm pretty sure it's a 1.8x1mm

 

[nobody1]

In the end I caved and bought a Hatsan jet 2 in .177 from MidwayUSA (about $160 shipped).
To my surprise it is not bad.
The acceptable accuracy (3/4-1 inch at 18-20 yards) is the main weak point.
Ergonomics are really good.
Trigger is very good.

Even the shot string is good after doing some mods.

With my .177 Jet 2 I have managed to get 6 magazines (48 shots) with 7.5-8 grain pellets in the 740-780 FPS range from 250 bar to 130 bar.
These are the mods:
-removed the 2 hammer spring preload washers
-added 1 M3 nut as preload to the valve spring
-placed 1 washer on the valve stem where the valve spring sits
This washer will restrict the air flowing into the barrel, and also acts as valve spring preload.
Initially the washer was restricting most air and got velocities in the 400 FPS range.
I ground the washer outer diameter a little to allow more air to pass.

 

[Ek Air Jay]

I too have a snapped off valve pin in my jet as well. Stock hammer spring and only about 2 tins of pellets put through it. Hatsan sent out the parts with my proof of purchase so that's nice but why am I having to fix a gun that is not even 1yr old yet? The new jet 2q.e.r is out now and it has the slightly longer barrel and a factory moderator. They should have waited to release this gun until they came up with the QER design imo.