FX Impact Tuning - Power wheel versus Valve Spring adjustments

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ua5qb

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Jun 11, 2018
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Still coming to grips with PCP things.

My days old FX x Impact .22 Cal, with the hammer wheel at high pills nearly punches through 2mm still at 10m, 958fps with JSB 18.13gn. A bit more than I need for birding. Wound the hammer adjuster wheel to Min, velocity dropped to 838 fps. Running at 232bar. As I understand the preload on the hammer determines how long the tank valve stays open. The regulator is set to 150 bar. What difference does turning the valve adjuster in or out make given the regulator is set at 150bar. The pill will receive its 150bar puff of air to send it on its way.

At min hammer setting groups are tighter, 15 shots 8mm hole at 15m. Very happy but would like to see if I can get more shot from a fill, while maintaining accuracy.




 
No puff of air from the FX. Although I did get the puff from my Evanis S10 when using H&N Rabbit Magnum pills. Went to a lighter pill and the puff stopped. Can only assume the O ring wasn't strong enough to contain the air pressure needed to get the pill moving. From memory they are 24gns, absolutely deadly in rabbits, but longer and had trouble feeding them consistently through the magazine.
 
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I think firdt you should lower your reg pressure! 150 is pretty high fir a .22( i think)

When i had my impact .25 my reg was at 130 max.

You should lower the reg pressure and see where its at at 130. I would keep the valve adjustment around 2 or 3 lines anythingmore and your just wasting air. After that just adjust HST until the velocity and of course accuracy is where you like.

But with theimpact you'll know when everything is tuned together and working in harmony. The gun will get really quite and just sound good to the ear. Youll know when its there.

Also youll most likely get alot more shots. With my .25 using 34s at 860fps i was getting over 110 shots on a fill
 
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Hey mate. I have the same gun and do the same thing you are trying to do. Change your reg pressure down to 120bar or so. Mine does 900fps with the 18.13 jsb on level 3. (I've adjusted the slack out of the sliding part in front of the wheel so my 25 cal barrel gets 860fps with 34 grain mk2 on max. and reg at 140) if you only have the 22 then leave that alone. When I want low power I put the power wheel on min. and then wind the valve travel adjuster in until the power comes down to where I want it. It restricts the valve travel and saves a heap of air. Huge shot count. Approximately 12 fpe is great for shed work. I have a post about an idea for fx barrels just yesterday that would really be worth a look as it addresses this situation exactly. 
 
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Hey mate. I have the same gun and do the same thing you are trying to do. Change your reg pressure down to 120bar or so. Mine does 900fps with the 18.13 jsb on level 3. (I've adjusted the slack out of the sliding part in front of the wheel so my 25 cal barrel gets 860fps with 34 grain mk2 on max. and reg at 140) if you only have the 22 then leave that alone. When I want low power I put the power wheel on min. and then wind the valve travel adjuster in until the power comes down to where I want it. It restricts the valve travel and saves a heap of air. Huge shot count. Approximately 12 fpe is great for shed work. I have a post about an idea for fx barrels just yesterday that would really be worth a look as it addresses this situation exactly.
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Ta cobber, removing the slack from the power wheel sliding bar is it worthwhile? Wound the valve travel adjuster in, went a bit to far velocity dropped to low 700fps. Have it back to 858+/- fps now. Getting down to 12 fpe, isn't that going to take reg below 100bar, not recommended by FX? I'm using chairgun to plot the trajectory of each adjustment based on the chrony reading. just need to bring the MacBook down into my reloading room. Very interesting how the PBR splits once the zero point passes 30m, at the afore velocity each 10m increment has a PBR of 6m up til 70m where the PBR drops to 3m out to 100m zero, theoretically. Where about are located?
 
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If you lower the reg pressure be sure to remove the cylinder and fire a few shot to dump the pressure. According to Airgun Depot the .22 Impact reg should be set to 110 to 115 BAR. I believe most run with the valve open and the power wheel set for a velocity around 900 for best accuracy, gas use.
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The correct procedure to lower the regulator pressure is to unscrew the bottle, then with the gun upside down, first tun the regulator counterclockwise to increase it's pressure. You will hear the remaining air escape. Then turn the regulator clockwise until it stops. This sets the regulator to zero. Set the power wheel to MAX. Now screw the bottle back on and turn the regulator counter clockwise a little at a time until you reach the desired velocity. Have the valve stop out to line 4 while adjusting the regulator and checking velocity. After you reach the desired velocity, start turning the valve stop back in a little at a time while checking velocity. When velocity just starts to drop you're tuned for maximum shot count at that regulator pressure. NEVER lower regulator pressure while pressurized as this can damage the regulator.
 
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I tried just using the power wheel and valve screw. Didn't work. Couldn't get the consistency I needed for some reason. Finally, I set the power wheel to full, moved the valve screw all the way out and adjusted the regulator down (scared me half to death after all the warnings about lousing up the reg), and after the regulator went to about 120 bar, I started getting the speed and consistency I wanted. Shots now are within a couple FPS of each other and shooting experience improved immensely.

Shoots so much better now, can't believe it. Adjusting the regulator really did the trick.
 
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On advice from FX, set power wheel to min, remove the tank, discharge any remaining air (dry fie), gently screw reg clockwise till it stops, reattach tank. Reg should read approx 40bar. Now slowly/carefully turn reg counter clockwise, stop every 1/4 turn and check gauge under stock. .22 & .17 best performance is 100 to 120 bar. Th gauge can take its time to change up. Using chrony adjust the valve stop to achieve consistency.

But also gave a caveat that not all guns are the same, adjust the regulator to get consistent velocities, which should yield more accuracy.

Advised not to shoot with reg set below 100bar
 
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The UK guns have the reg set to 55bar, how come you guys in the US will break them when under 100bar? Conflicting info out there.
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I had heard that there is some different reg/valve parts in the UK 12 ft/lb rifles.
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Actually, shooting with the air pressure in your tank at under regulator pressure (below 100 bar) is OK. That won't damage anything to my knowlege. If you set the regulator on FAC versions below 100 bar, it may leak among other problems. Watching the Earnest Rowe videos on YouTube, looks like setting below 100 bar moves one "o" ring too far forward and out of the housing so the regulator doesn't seal properly. That can cause problems.

Having said that, the regulators on FAC and sub-12 FPE versions must be different. I do know that a sub-12 FPE version cannot be tuned up to higher energy, so the parts must be different.
 
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