Umarex Umarex Zelos hammer spring

Jump to latest Follow Reply
N

nobody1

Member
Sep 4, 2021
616
426
WA, United States
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:

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 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.

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

20240918_134524.jpg


20240918_134503.jpg
 
Last edited:
  • Like
Reactions: Gramps, Firewalker and Stubbers
nobody1 said:
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:

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
Click to expand...

Thank you sir!!
 
  • Like
Reactions: nobody1
Upvote 0
Stubbers said:
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
Click to expand...
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.
 
  • Like
Reactions: Firewalker and Stubbers
Upvote 0
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.
 
Last edited:
  • Like
Reactions: Stubbers
Upvote 0
nobody1 said:
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.
Click to expand...

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

-Matt
 
Upvote 0
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.
 
Last edited:
Upvote 0
You must log in or register to reply here.
Top Bottom
Back
Home
Forums
Resources
Menu