Umarex Zelos Hammer Spring Adjustment

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

-Matt
 
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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.
 
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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.
 
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IMO, bone stock, default factory setting, gun is over sprung. Mine is the same. 2100, all the way backed out was peak velocity. With CW 1/8th turn lost 3-5 fps. Went up to 2350, 22gr slugs were at 857 at 2100, at 2350 with no spring adjustment 896. With adjustment peaked at 913. ⅛turn past this, down to 904, another down to 887. Found 21gr HN shoot best anyway. 927 is plenty.

Bottle and adapter en route. Have new valve and housing on way. Going to add side mounted plenum... I'm not looking for much more power, would like to have the 21grs in 940-950 neighborhood.


Shot cycle was nicer at higher pressure with very little spring added.
 
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