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I was running some chrony test this morning on some EJ’S and Kodiaks, both were coming in just as expected. I decided to top off my tank and recheck at 2900 psi when I discovered that my velocity dropped off by 200 fps with my Kodiaks. Wo , what happened? I check and refilled the bottle again, still the same results. Any ideas?
Thanks,
Mike 17670 😯
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Every valve seems to have a slightly different “sweet spot”. My current setup (talon tunes 24″ .25) with condor tank and heavy hammer likes 2650psi start (higher gives reduced velocity for 10-15 shots) 20 shots between 950-1050-900fps ending at 1800psi. My modified talon tank on same setup starts at 28-2900psi, 35-40 shots from 800-940-850fps ending at 2000psi. Just experiment with fill pressure until you find the satarting point for velocity you want. In my case, I kinda like the condor tank’s lower pressure preference as it is much easier to fill with my hand pump.
To tell the truth many PCP’s do better out of the gate with a 2800 psi fill over a 3000.
Glad you sorted it out.
New valve,I think, new gun should be a new valve you think? Your explanation makes sense though. When I preloaded the PW to 11 to shoot the EJs, my velocity was normal for that pellet at that PW rate.
Only when I backed off the PW, I saw a large difference, i.e. spring wasn’t strong enough to open the valve all the way. I know I didn’t put over 3000 psi in the bottle. Is it better to stay closer to 2800 or 2900 psi when refilling? Oh well, live and learn.
Thanks, Mike17670
Thanks,
Mike 17670 ❓
You can try turning up your power wheel and see if this is the cause. Or you can fill just to the point before velocity drops off. Or using a heavier hammer will help knock it open and these can be purchased from Talon Tunes.
Took your advice and you were correct, the velocity returned after 30 some shots. What happened, is this common, and what can I do to prevent it from happening again?
Thanks,
Mike 17670 ❓
First off a question. Do you have the new Condor valve or the original one?
One thing happens in unregualted airguns. As you increase the pressure in the tank, the pressure keeping the valve closed is also increase. This makes knocking the valve open harder with higher pressures.
Could it be possible your gauge is off somewhat and it got filled over 3000psi. Or did you sit it in the sun for a period of time?
shoot 10-15 shots and see if you get your velocity back. sounds like valve lock maybe fill is over 2900 or your previous fill was closer to 2800psi
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Is there a reason NOT to want a “rainbow” velocity curve? I mean once you know what it’s doing, seems to me it’s better. I’m still learning but this is what i’m going to try, I know my gun doesn’t give optimum velocity on a 3000 fill, so, I have a 20 round pellet holder on my tank and i am going to max out my p.w. and shoot 10 to 20 to see what it does. Then, using the holder to tell me when i need to adjust down (after 10 or 20 rounds) I can dial it back to try to keep her around 900-950. Then after around 20 rounds i’ll know it’s time to adjust back up. I’m going to try this today with C.P.’s I’ll post my results later. Also if you know your shop is filling to 3000-3100 at 77-79 degrees. Can’t you use that as one way to verify that your gauge is accurate? I like my shop because he always makes sure to double check your pressure after it has sat for a bit to see if it needs a bit more.