Tuning FX Impact Mk2/M3 - slower first shot - no reg creep - quasi-scientific analysis

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They must of changed something in the m3 the sticktion after 2 days of sitting under pressure wasn't that bad would it make a difference changing to the pp of the m3 I believe they make them for mk2 I don't know what is all inside them just asking and I'd rather find a different solution than shelling out more for another power plenum kit
 
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M3 may have the exact same issue. As I mentioned, it can be reduced if you set your gun at plateau, not a knee of your velocity.
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But if you set your gun on the plateau you will never maintain an accurate slug tune from a full fill to refill. Trust me. So we’re back to it needing to be fixed or being a shot dumper with a $2,000 gun. Did polishing the rod help at all?
 
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Does the rod that the hammer rides on that goes into the plenum and valve correct does the other end of that rod end at block right where mag is seated ? I thought it did and that was the reason I thought it was more of a balance valve but it must not be as you can tell I haven't had my mk 2 apart yet it's pretty new only switch out barrels and reason I have so many questions
 
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You are very right about the slugs and tuning for them. Keeping the gun at plateau is not that efficient and the gun sounds out of tune.

Rod polishing did not help.

I doubt X-ring can help.

There is a way to fix it: https://www.barnwell.co.uk/what-are-back-up-rings/

P.S. Looking at the M3 diagram I am almost sure the same issue is there.





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Actually it’s the ever descending shot string that lets the gun harmonically fall off a slug tune when you’re set at the plateau. Since I retired last year I’ve been working part time at my buddies hydraulic shop. We use back up orings all the time on the gland of a hydraulic cylinder. They are used in an oring groove. They give a high riding oring a little more room to compress than if it was just sitting in a snug groove. Backup orings floating on a rod won’t serve any purpose.
 
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Great topic, guys. I’ve wondered about this for a few months now, as there’s been a few times I’ve opened up an impact due to a leak and have either found the buna o ring that sits on top of the PUR completely destroyed or completely gone from within the plenum. 


ive wondered at times when cocking the gun with the gun completely drained if that PUR o ring traveled back with the rod, and never goes back to its proper spot. 
im following this thread for sure. Good stuff
 
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Great topic, guys. I’ve wondered about this for a few months now, as there’s been a few times I’ve opened up an impact due to a leak and have either found the buna o ring that sits on top of the PUR completely destroyed or completely gone from within the plenum. 


ive wondered at times when cocking the gun with the gun completely drained if that PUR o ring traveled back with the rod, and never goes back to its proper spot. 
im following this thread for sure. Good stuff
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Sometimes you have to be patient and not give up sniffing around for an intriguing topic. I know all the I need settings and the like topics are turning the forum into a kindergarten but a good one pops up every now and then. My jonesing for intriguing topics has lead me to read some about guns I don’t even own. Hopefully you might have some input here.
 
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I shoot with reg pressures from 130-150b. I wonder if a guy with a 85b pellet tune experiences this same phenomenon? Is the problem with my M3 not as drastic as it is with my M2 because the oring on my M2 has been taking a beating for much longer? I hate to tear down my M2 and replace that thing because the gun is dialed in but it sure would answer some questions.
 
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M3 may have the exact same issue. As I mentioned, it can be reduced if you set your gun at plateau, not a knee of your velocity.
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What do you think if I make a new front part of plenum with the mk1 design. In mk1 design the O ring was inserted from the front and there was a tight groove in which this O ring used to sit and then there was a nut / screw that held it in place tightly. Not a slight movement was possible neither any gap for wedging as I feel. 

I feel that in mk1 arrangement there was little chances of wedging. 

While in mk2 and m3 as the O ring enters from rear and there is no groove inside the plenum to properly hold the O ring, we face all this issue. 

I also think that FX would be reading.

Do I make a sense in making the arrangement of mk1 for my m3?

In mk1 there was no such issues. 

Bhaur 
 
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Ptfe oring with a regular oring to back it up isn't that the same thing a x ring or quad ring does seals in 2 spots one on the front and one on the back and creates a pocket for silicone to ride in to help lube it would be the same on the inside of the quad ring and pocket holding silicone cone lube would only help wouldn't it they are less likely to roll also I don't know just thought if your putting 2 orings on the rod wouldn't it be worse than just using a quad ring maybe I'm thinking about this totally wrong and I don't know 
 
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