Anyone done any chronograph testing experimenting with min to max hammerspring adjustment with no mods and factory reg setting on the notos?
Umarex Notos hammer spring adjustment
- Thread starter tsmith
- Start date
In stock form there is not much hammer spring adjustability.
There are probably 3 hammer spring turns, and the fps is almost the same at min or max.
Many posts on adjusting or tweaking the hammer spring on this forum.
Just look for them.
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I tried adjusting mine down to no avail. The spring is too heavy to give much adjustment at all. If you’re trying to increase power, there’s no much left up too without some porting and an add on plenum to help.
I’m hoping for a lighter or shorter spring to help mine get a little lower in the power department.
I’m hoping for a lighter or shorter spring to help mine get a little lower in the power department.
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If you drill out the hammer and remove about 3mm of material you can get more adjustment on the hammer spring. A 3/8 endmill fits the hammer hole just about perfect
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I added the eBay plenum, lowered the regulator to 100 bar and removed 3 coils from the hammer spring. Now, I can adjust for JSB 15.89, 640~680fps. 54~50 shots on the reg.
Happy with the accuracy.
Happy with the accuracy.
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The regulator comes to about 2000psi (140 bar) from the factory, I am not sure what you did.
To drop velocity the easiest way is a weaker hammer spring.
You will find several of my posts explaining how I did that.
To drop velocity the easiest way is a weaker hammer spring.
You will find several of my posts explaining how I did that.
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I goofed on reporting the pressure & just corrected it to 100bar/1400psi. I was looking for more shots per fill and this combination worked out well for me.
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i drilled out the hammer about 2-3mm to lighten it and cut my spring 1/2 a coil on both ends. i put a washer between the spring and the hammer spring adjustment screw. i also took some aluminum from behind the hammer spring adjustment screw so i can back that screw out farther. i don’t remember the sizes but i did port all airways including the barrel itself to match the others. i can adjust my fps anywhere between 645-880fps with 14.3 CP but i have it shooting 800-810 with 18.1 at the moment. i get about 23-25 shots at this tune with the plenum. the regulator is still at factory setting. i want more regulated shots but can’t get myself to leave this shot count to power ratio..
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That is a massive power increase over the stock Notos.
I was not after power, so I drilled nothing.
For more FPS adjustability I just used weaker hammer springs, no other mods.
In one Notos I can got from about 460 FPS to 620 FPS and in another Notos from about 600 to 740 FPS, all with CPHP.
I was getting 100 shots in the 460-490 FPS range, and 50 shots in the 680-700 FPS range.
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i tried to tune for a target of 720-730 fps with chcp to have a higher shot count but i couldn’t get my shot spread to stay within +/-6 fps from the previous shot.
tip: the cocking lever is angled in a way that doesn’t allow the hammer to be pulled straight back. this leads to the front of the hammer to rub against the side walls of the aluminum around it. this is the grittiness felt when cocking the lever. round off and polish the front edge of the hammer that strikes the valve pin with some sand paper. this will prevent the aluminum from getting damaged by the steel hammer whenever the gun is cocked. smoov lever action after that
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