Umarex Zelos Hammer Spring Adjustment

[Jack Hart]

I'm not so worried about correcting an oversprung valve. I'd just like to know that once I get the regulator pressusre and hammer spring tension set properly that I won't have to mess with it if I change pellet weight, assuming I'm willing to accept a change in fps.

 

[Stubbers]

I'm not so worried about correcting an oversprung valve. I'd just like to know that once I get the regulator pressusre and hammer spring tension set properly that I won't have to mess with it if I change pellet weight, assuming I'm willing to accept a change in fps.

Yes, you'll be fine if you're willing to accept whatever change in fps there is.

-Matt

 

[Jack Hart]

Here are a few data points for new Zelos owners:

I increased my regulator pressure to 2250 psi and was able to screw in the hammer spring adjustment 2 turns from full out to get a maximum velocity average of about 975 fps with 18.14 gr Diablos. Screwed back out 2 turns gives an average velocity of 950 fps. I'd like a little more range of adjustment, but I guess it is what it is unless I want to try modifing the hammer spring as has been suggested. BTW, at this setting the rifle shoots 25.39 gr JTS Dead Centers at an average of 865 fps which is about what I want.

 

[JimD]

I'm glad you found a tune that may work for you. 950 seems a bit fast for the 18s and if you agree then you might try a little less regulator pressure. But 865 on the 25.4s seems good and driving them any faster would make the 18s really high. 21 grain should be faster without going really high. I have my Caiman X tuned to shoot 18 grains at about 910 fps and it is very accurate there. My P35-22 is tuned to shoot 21 grain at about 820 and is equally accurate with the Caiman.

I only change the regulator pressure if the gun likes a pellet of a particular weight but then the current tune shoots them lower than 800 or much higher than 900. I see much bigger accuracy changes from changing pellets than I do changing pellet speed.

 

[Rocko]

It's all a delicate dance between pressure, hammer spring, port size and pellet weight. Change any one thing, and it affects the result. Plus, if you have an inconsistent regulator, it can get very frustrating.