GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: vinenator on April 21, 2015, 05:35:25 PM
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I took my two PCPs out for use after sitting for a few months over winter.
i noticed some strange behavior between then and now.
My Marauder now appears to be shooting hot by about 4%. That is, the shot string is using the same pellets is now shooting near 950fps where as it was near 910fps last fall.
I stored the rifle indoors at room temp with a charge on the air cylinder. it didn't appear to loose any air during storage.
1. what could account for this?
2. is it better to store PCPs with a charged tank or an empty one if one is not going to use them for an extended time?
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Shooting HOTTER would using the lighter hammer IMO would indicate Regulator Set point had dropped slightly.
* Have you made note on WHAT GAUGE pressure read before and now ?
Bevel washers will take a compression set over time and if / when they do the Regs seat will cloose sooner and a lower regulated pressure.
Easily enough corrected with a slight setting tweak.
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Scott, correct me if I'm wrong, but if the ball in the end of the piston which seals on the seat in the regulator body compresses over time, would it not require the piston to move further to seal?.... If that is the case, the piston would compress the Bellevilles slightly, and increase the outlet pressure required to get the regulator to stop flowing air, increasing the setpoint slightly, and resulting in a higher velocity.... unless you are operating well down on the downslope (valve locked side) of the velocity vs. preload curve....
I store all my PCPs with nearly a full charge, so that they are ready to use at any time....
Bob
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Scott, correct me if I'm wrong, but if the ball in the end of the piston which seals on the seat in the regulator body compresses over time, would it not require the piston to move further to seal?.... If that is the case, the piston would compress the Bellevilles slightly, and increase the outlet pressure required to get the regulator to stop flowing air, increasing the setpoint slightly, and resulting in a higher velocity.... unless you are operating well down on the downslope (valve locked side) of the velocity vs. preload curve....
I store all my PCPs with nearly a full charge, so that they are ready to use at any time....
Bob
Bob,
The AGE regulator ( HuMa ) uses a Flat floating disk seat and Does not indent. So the adjusted length of spool HP end to seat never changes over time. However any changes in spring rate of the bevels changes set point.
As stating of the NINJA regulator ... there cone / ball seat as it indents INCREASES the distance spool must travel to set seat closed. With spring / bevel values remaining constant, Set point will RISE as seat wear happens.
* A leaking seat also raises the discharge side pressure if allowed to sit for a spell. So long as rate of fire is greater than the leak rate you will get consistent shots.
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* Have you made note on WHAT GAUGE pressure read before and now ?
yes, the regulated pressure seems to be slightly higher (100psi'ish).
thanks for the input
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* Have you made note on WHAT GAUGE pressure read before and now ?
yes, the regulated pressure seems to be slightly higher (100psi'ish).
thanks for the input
That is Odd ... generally when firing valve operating pressure rises, it becomes harder to crack open and therefore we get a LOWER velocity. Especially with a light hammer.
Ah the not so black or white science of PCP's :o