regulator setting to spring tension

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daddypaddy

daddypaddy

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Jul 31, 2023
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san jose, ca, usa
i have a fully ported notos with stock tube and the factory setting regulator shooting 25 grain at 27.5 fpe. the hammer spring tension is about 70-75% tightened in at this fpe for this pellet but still sounds like it’s wasting air. my shot count is around 17-18 with this. i never messed with the regulator because up until recently, i have been using a manual pump and didn’t want to have to pump from empty multiple times while trying to tune my regulator.
my question is; can i tune the regulator down and use more hammer spring tension to achieve the same/similar fpe output?
 
The general rule of thumb is to be about 5% below the peak velocity for the regulator setting. To achieve this you shoot at increasing hammer spring tension until the velocity stops increasing. Then turn down the hammer spring to get about 5% less velocity. That will get you about maximum efficiency. If you do this and either the shot count is not high enough or the power is not high enough you can turn the regulator down or up as required.

My SPA (Snowpeak) built guns sometimes have a lower first shot velocity tuned this way. I believe your notos was built by SPA. So I would also check velocity after the gun sits overnight. If it is lower and that is important to you, you could increase hammer spring a little and it will probably go away.

But basically the process I use is to determine the maximum velocity I can get for a given regulator setting, look at what it will be 5% below that and if I do not like the result, change the regulator. On my Caiman X with a huma regulator I went much more than 5% below the peak by turning down the hammer spring. The gun was efficient but the first shot velocity was low. So I brought up the velocity with the hammer spring and it is fine at about 5-6% below peak.

I know what dwell is but I don't understand how to change it on fairly simple guns like my P35s or your Notos.
 
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JimD said:
The general rule of thumb is to be about 5% below the peak velocity for the regulator setting. To achieve this you shoot at increasing hammer spring tension until the velocity stops increasing. Then turn down the hammer spring to get about 5% less velocity. That will get you about maximum efficiency. If you do this and either the shot count is not high enough or the power is not high enough you can turn the regulator down or up as required.

My SPA (Snowpeak) built guns sometimes have a lower first shot velocity tuned this way. I believe your notos was built by SPA. So I would also check velocity after the gun sits overnight. If it is lower and that is important to you, you could increase hammer spring a little and it will probably go away.

But basically the process I use is to determine the maximum velocity I can get for a given regulator setting, look at what it will be 5% below that and if I do not like the result, change the regulator. On my Caiman X with a huma regulator I went much more than 5% below the peak by turning down the hammer spring. The gun was efficient but the first shot velocity was low. So I brought up the velocity with the hammer spring and it is fine at about 5-6% below peak.

I know what dwell is but I don't understand how to change it on fairly simple guns like my P35s or your Notos.
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i’ve read the article regarding how and why to tune 5% below peak velocity a while back. i just wanted to know if turning down my regulator and turning in my HST past 70-75% would net me the same velocity without the excess blowout of air behind the pellet.
 
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Stubbers said:
Increasing hammer weight increases hammer momentum, increasing hammer travel increases both momentum and FPE/kinetic energy, and increasing hammer spring rating / preload increases FPE/kinetic energy. Momentum effects dwell more than lift while FPE/kinetic energy effects lift more than dwell.

-Matt
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so according to this, i would for sure need to increase the weight of the hammer and maybe a need stiffer spring. 🤔

i was imagining master Yoda’s voice while reading your reply.. probably how it was worded.
“anger leads to hate, hate leads to suffering”
 
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I'm not sure what "wasting air" sounds like. But my guns tuned to be a little under the peak velocity for their regulator setting have always sounded fine to me. They use a bit more air and get louder if I increase the fpe. I don't know where you are relative to the peak for your regulator setting and if you also don't know I would figure that out first. If the sound still bothers you when you decrease the hammer spring some from the peak, then you might want to try what I view as more complicated things like changing the hammer mass. But I would start with the basics and see where that gets you. Another way to change the sound is the moderator.

At 27 fpe and a little under 20 shots I don't see where you are using too much air. My unregulated Prod is tuned to about 18 fpe and only gets about 20 full power shots before it starts falling off more significantly. The fill pressure is higher on the Notos but I think the air tube volume is similar. I'm not sure how all that balances out but I think 27 fpe is a lot for this little gun. I find my Prod is quite effective on squirrels at short range. I have other guns at higher fpe and they do drop them a little quicker but the difference is not very large. My Prod has shot through both sides of a squirrel with a chest shot. If you want more shots I would be thinking about a tune around 20 fpe. Trajectory and killing power should be fine.
 
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JimD said:
I'm not sure what "wasting air" sounds like. But my guns tuned to be a little under the peak velocity for their regulator setting have always sounded fine to me. They use a bit more air and get louder if I increase the fpe. I don't know where you are relative to the peak for your regulator setting and if you also don't know I would figure that out first. If the sound still bothers you when you decrease the hammer spring some from the peak, then you might want to try what I view as more complicated things like changing the hammer mass. But I would start with the basics and see where that gets you. Another way to change the sound is the moderator.

At 27 fpe and a little under 20 shots I don't see where you are using too much air. My unregulated Prod is tuned to about 18 fpe and only gets about 20 full power shots before it starts falling off more significantly. The fill pressure is higher on the Notos but I think the air tube volume is similar. I'm not sure how all that balances out but I think 27 fpe is a lot for this little gun. I find my Prod is quite effective on squirrels at short range. I have other guns at higher fpe and they do drop them a little quicker but the difference is not very large. My Prod has shot through both sides of a squirrel with a chest shot. If you want more shots I would be thinking about a tune around 20 fpe. Trajectory and killing power should be fine.
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thanks for the input. i very rarely have it tuned for 25gr at 27fpe. i just wanted the community’s input on the circumstance. it’s normally at around 21-23fpe with 14.3gr.
you’re right. i don’t want to mess with hammer mass anymore than i already did before when modding the notos in the beginning.
 
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