Umarex Umarex Zelos hammer spring

[nobody1]

UPDATE
Instead of the 9mm OD spring I started using the 8mm OD spring.
The 9mm OD spring was rubbing against the hammer which caused inconsistent velocities, a 30-40 FPS spread.
The 8mm does not have the rubbing issue.

Original post
I have got my Umarex Zelos .22 caliber a few days ago.

The original hammer spring is too strong to get a good tune.
When you increase the hammer spring the velocity usually drops a few FPS.
This is with the regulator at 1750-1800 PSI.

These are the OEM hammer spring dimensions:
Length: 63.5mm
Outer diameter: 8.5mm
Wire diameter: 1.2 to 1.3mm (coils are too tight to measure accurately)

I have managed to use a different hammer spring I bought from Aliexpress:

https://www.aliexpress.us/item/2255800219014836.html

I bought the springs with these specs:
Outer diameter: 9 mm RECOMMEND the 8mm OD
Wire diameter: 1.2 mm
Length: 100 mm

I have used the 9mm OD spring (cut at different lengths) in the SPA PP750 and the Umarex Notos.

For the Zelos I have ended with the above spring cut to about 56-58mm length.

In the photos bellow the OEM spring is on the left and the spring I used is on the right.

 

[Stubbers]

That ought to do, trial and error my friend!

I would heat up the cut end and then close it with a pair of needle nose personally, and maybe sand/grind it flat like OEM.


-Matt

 

[Firewalker]

I have got my Umarex Zelos .22 caliber a few days ago.

The original hammer spring is too strong to get a good tune.
When you increase the hammer spring the velocity usually drops a few FPS.
This is with the regulator at 1750-1800 PSI.

These are the OEM hammer spring dimensions:
Length: 63.5mm
Outer diameter: 8.5mm
Wire diameter: 1.2 to 1.43mm (coils are too tight to measure accurately)

I have managed to use a different hammer spring I bought from Aliexpress:

https://www.aliexpress.us/item/2255800219014836.html

I bought the springs with these specs:
Outer diameter: 9 mm
Wire diameter: 1.2 mm
Length: 100 mm

I have used the same spring (cut at different lengths) in the SPA PP750 and the Umarex Notos.

For the Zelos I have ended with with the above spring cut to about 56-58mm length.

In the photos bellow the OEM spring is on the left and the spring I used is on the left.

There is another discussion about the Zelos hammer spring here: https://www.airgunnation.com/threads/zelos-hammer-spring-adjustment.1319310/

View attachment 497334

View attachment 497335

Thank you sir!!

 

[nobody1]

That ought to do, trial and error my friend!

I would heat up the cut end and then close it with a pair of needle nose personally, and maybe sand/grind it flat like OEM.


-Matt

I cut all my springs with a rotary tool and use the same cutting wheel to flatten and polish the cut end of the spring.

 

[nobody1]

Thank you sir!!

I corrected some mistakes in my original post.
Those mistakes are not reflected here.

 

[Firewalker]

All good!

Thanks for doing the hard work of researching and posting links. BIG help!

 

[nobody1]

All good!

Thanks for doing the hard work of researching and posting links. BIG help!

I just wish more people provide this kind of useful information when they have it.

 

[Firewalker]

I try to remember to do so. I get pretty busy and I forget.

 

[nobody1]

With the regulator set at 2000 PSI and with the above hammer spring cut to about 56 mm I get a range of 780 FPS to 930 FPS with Norma 17.6 grain pellets.

The 780 FPS is with the hammer spring guide flush with the end of the receiver.
The 930 FPS is about 4 turns in.
If I go to the end (about 6 turns in) the velocity drops to about 910 FPS.

 

[Stubbers]

With the regulator set at 2000 PSI and with the above hammer spring cut to about 56 mm I get a range of 780 FPS to 930 FPS with Norma 17.6 grain pellets.

The 780 FPS is with the hammer spring guide flush with the end of the receiver.
The 930 FPS is about 4 turns in.
If I go to the end (about 6 turns in) the velocity drops to about 910 FPS.

Found the plateau and can tune down to 780 fps, really good data points for those that want to achieve similar, good work.

-Matt

 

[nobody1]

I am at about 890 FPS now at 2 turns in.

I tried 1.5 hammer spring turns in from flush (about 875 FPS) and 2.5 turns in (about 895 FPS).
Both of those were louder, which usually means less efficient.
No idea why the 875 FPS at 1.5 turns was louder than the 890 FPS at 2 turns in.

I am getting 60-65 shots from about 3600-3800 PSI down to 2000-2200 PSI.

 

[Jack Hart]

Great info. Now if there were only a video or step by step instructions available that explain how to change the Zelos hammer spring. Hint, hint.

 

[nobody1]

I have watched several videos:
start at minute 5 =>

start around minute 6 =>

Those videos showed me how to remove the stock and adjust: hammer spring, trigger, regulator.
There may be several other videos.

The Zelos is the same as the SPA (Snowpeak) M60.
There may be some other M60 videos.

 

[nobody1]

I updated my original post.
I recommend using the spring with 8mm OD instead of 9mm OD.

 

[Perle]

Good stuff buddy