FX Impact M3 valve adjuster hitting barrel shroud

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Floridaman2005

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Oct 11, 2024
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Stuart, FL, USA
Hello Nation,

Just purchased a new .22 Impact M3 and was going through all the basics and setting up the rifle. When attempting to adjust the valve adjuster, I noticed that the valve adjuster was hitting the barrel shroud, making it impossible to open passed 3.5 lines. This is my first PCP so I’m still learning everything. What do I need to adjust in order to move the shroud away from the valve adjustment knob?

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My M3 compact .22 does the same thing. But fortunately when the valve knob is backed out and touching the shroud, it is out far enough that it isn’t working. Before you start screwing around with stuff, back yours out until it hits the shroud. Shoot a couple shots over the chronograph. Now turn the knob in a quarter turn. Shoot again and see if your velocity has dropped. If it didn’t then you don’t need to worry about a thing. Fx may install a slightly different valve spring on the compacts to accommodate the tight clearance from the knob to the shroud.
 
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Vetmx said:
My M3 compact .22 does the same thing. But fortunately when the valve knob is backed out and touching the shroud, it is out far enough that it isn’t working. Before you start screwing around with stuff, back yours out until it hits the shroud. Shoot a couple shots over the chronograph. Now turn the knob in a quarter turn. Shoot again and see if your velocity has dropped. If it didn’t then you don’t need to worry about a thing. Fx may install a slightly different valve spring on the compacts to accommodate the tight clearance from the knob to the shroud.
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Great point 👍 I have a chronograph on the way and will get to the bottom of that and try that asap. Thank you!

My only concern would be if it didn’t effect what I was doing now but may still be limiting when I move to heavier ammo and when I turn up the volume.
 
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coastal drifter said:
Might want to call Utah airguns , It just doesnt make sense to me that you cant adjust the vavle adjuster.
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I agree, and it definitely isn’t just mine, there’s a few message board last I’ve found discussing the issue. Nobody really has a fix besides cutting some washers and putting them inside the shroud, but I’m not really a fan of that.
 
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Floridaman2005 said:
How do you remove the shroud? Will this cause any fitment issues?
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The shroud simply unscrews. It is threaded at the end. Your best choice is to probably slightly unscrew the shroud to get the valve adjuster where you want it. Once completely tuned you may find it isn’t an issue and the adjuster will want to be in that far anyway. Maybe not though. If you end up needing it out further than the shroud will allow I personally would unscrew the shroud (not completely just loosened) to the point needed. You could always put a dab of blue loc tite to help secure it in its un tightened state. I would not move the whole barrel assembly forward as I would think that would misalign the transfer port of the barrel.
 
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Trucker3573 said:
The shroud simply unscrews. It is threaded at the end. Your best choice is to probably slightly unscrew the shroud to get the valve adjuster where you want it. Once completely tuned you may find it isn’t an issue and the adjuster will want to be in that far anyway. Maybe not though. If you end up needing it out further than the shroud will allow I personally would unscrew the shroud (not completely just loosened) to the point needed. You could always put a dab of blue loc tite to help secure it in its un tightened state. I would not move the whole barrel assembly forward as I would think that would misalign the transfer port of the barrel.
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Yeah I agree, but I’m not a fan of leaving the shroud loose because that would make things less accurate, or at the very least would make the moderator more susceptible to baffle strikes.
 
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Floridaman2005 said:
Great point 👍 I have a chronograph on the way and will get to the bottom of that and try that asap. Thank you!

My only concern would be if it didn’t effect what I was doing now but may still be limiting when I move to heavier ammo and when I turn up the volume.
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Quite the opposite. When you turn up the volume, your operating range with the valve knob stays pretty much the same because you have more plenum pressure working against it.
 
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It’s not an issue until you test it and determine if it’s an issue. Everyone is jumping the gun here. My knob can hit my shroud on my compact but it doesn’t matter because it’s in the wide open mode when it’s touching. The only thing that could bite you is if who you bought it off of made the gun a compact. If it came from FX that way, you should be fine.
 
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Vetmx said:
It’s not an issue until you test it and determine if it’s an issue. Everyone is jumping the gun here. My knob can hit my shroud on my compact but it doesn’t matter because it’s in the wide open mode when it’s touching. The only thing that could bite you is if who you bought it off of made the gun a compact. If it came from FX that way, you should be fine.
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It’s definitely an issue. On my Impact Compact, I can turn the valve adjuster fully open past the fourth line without it hitting the shroud—there's still a few millimeters of clearance. If your valve adjuster has the standard 4 lines but can only reach the 3th line before touching the shroud, then something’s not right. Even if it doesn’t affect velocity, the adjuster should be able to open fully without obstruction.

The valve adjuster is the magic touch when tuning the impact.
 
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Ries said:
It’s definitely an issue. On my Impact Compact, I can turn the valve adjuster fully open past the fourth line without it hitting the shroud—there's still a few millimeters of clearance. If your valve adjuster has the standard 4 lines but can only reach the 3th line before touching the shroud, then something’s not right. Even if it doesn’t affect velocity, the adjuster should be able to open fully without obstruction.

The valve adjuster is the magic touch when tuning the impact.
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You’re preaching to the choir about the FX Impact. But I didn’t realize he was only at line 3. Mine stops about line 4. And all of my Impacts generally start to work about half way between line 3 and 4. I was reading some of this while in my tree stand. But I would still like to see what his chronograph has to say. All it takes is a different spring in there and you can grow or shrink the adjustment range on that knob.
 
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So, it’s been a while since posting and wanted to provide an update incase anyone in the future has this problem.

My shroud is exactly 6 5/16” long so that seems normal. I learned a lot more about the gun in the last few months and the easiest solution was to find some small washers and put them over my barrel lock nut against my barrel liner so when I screw in my shroud it would give me just a few extra mm of clearance so I could go out to at least the 4th line on my valve adjuster. Simple fix really, just needed some time and experience to figure it out. Will update with pictures later for anyone else who comes across this thread.
 
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Floridaman2005 said:
So, it’s been a while since posting and wanted to provide an update incase anyone in the future has this problem.

My shroud is exactly 6 5/16” long so that seems normal. I learned a lot more about the gun in the last few months and the easiest solution was to find some small washers and put them over my barrel lock nut against my barrel liner so when I screw in my shroud it would give me just a few extra mm of clearance so I could go out to at least the 4th line on my valve adjuster. Simple fix really, just needed some time and experience to figure it out. Will update with pictures later for anyone else who comes across this thread.
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Since you provided an update, I will too. Since this topic I switched liners and projectile with my compact. My shroud became an issue just like your issue. I had to shorten the shroud. Everythings fine now. For guys who don’t have the equipment to shorten the shroud, this issue would be a bummer.
 
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Vetmx said:
Since you provided an update, I will too. Since this topic I switched liners and projectile with my compact. My shroud became an issue just like your issue. I had to shorten the shroud. Everythings fine now. For guys who don’t have the equipment to shorten the shroud, this issue would be a bummer.
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Yeah, it’s still an issue for me actually. I couldn’t figure out the spacers and eventually gave up and just made it stock again. Still can only get to about 3 1/3 lines on the valve adjuster. Next test will be to see if it’s actually limiting my fps more than I want it to. I’m only shooting 15.89g pellets so I should be able to get speed easily. I’m going to open the VA as much as possible and get the pellets going 940ish fps and then dial it in with the wheel and the VA. I have a feeling the VA will not be limiting my speed where it’s at. And if it does I’ll tune around it. Want to have my final velocity around 925 fps.
 
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Vetmx said:
Just back it out until it touches the shroud and get a chronograph speed. Then take the shroud off and back the knob off a half turn and shoot a loud shot over the chronograph. Then go from there.
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Yeah I’m gonna go the opposite direction. I’ll take chronograph reading with the VA as far out as it will go and then turn in 1/4 turn to see if speed drops and go from there.
 
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