Fx impact mk2 PP hissing sound

[lvc]

Hallo... I’m a new impact owner and from day one i noticed that when I take a shot I hear the plenum filling up directly after a shot. Here is the thing . it’s not consistent. One shot it hist (I think it’s the plenum filling up) for like 0,1 sec and stop.... you can barely hear it and next shot it’s 1 sec or something another time 0,5 sec or 2 sec. I noticed over the chrony that when the hissing is long the gun shoot low in fps... around 20 to 30 fps lower than when filling is instant...no filling sound. Every setting on the gun is from the factory. Regulator pressure is 85 bar... hammer spring knob on max. Valve stop 3. The gun is of course full. It’s a .22 cal. Shooting jsb 18,13 gn. Can someone point me in the right direction. Question: why this inconsistency and how can I fix it. Thank you in advance.

 

[jking]

My guess is the valve is not sealing good against the seat. There were some bad seats (believe me I know) where the machining wasn't very smooth and didn't seal 100%, 100% of the time. Can you say that the air comsumption is higher than you thought is should be? You might watch your bottle pressure also and note if it's falling off without shooting it. Thats my first guess, surely someone else will chime in. FX was good on mine and replaced the valve body and valve rod. 100% improvement. 

Jking

 

[2fast2furious]

That is normal with the pp and without. Sometime u can't even hear it. Other times its really loud u can hear it from across the room. It's just how it is. Can't do anything about it.

 

[Yo]

Darth Vader's ghost just visiting... Lucky for you it's not an RTI Priest or Prophet...That good ol Lord of the Sith really prefers to hang around those.

 

[lvc]

I have check for leeks. Full fill and check the next day. This is my first Fx so don’t know the shot count for a full fill. It’s over 100 shots. Can if be that the reg pressure is to low. Or what you said a bad seal.... or must I buy the new Huma reg.

 

[Yo]

I wouldn't worry about anything. Sounds like your gun is totally normal. If you need something totally quiet and worry free get a Daystate Pulsar or Redwolf instead.

 

[XMX]

I noticed this also when PP is filling.

Is there a standard bar reg setting from the factory? 

.22 ,700 mm barrel.

Just wondering .

Thanks

 

[Yo]

90 BAR is ideal if you have the PP.

 

[lvc]

Thanks... I don’t care that it makes noise. It’s like what I said. It’s the big inconsistency is the issue. When the PP fill instantly after a shot... I know that that shot will be 20 a 30 fps higher. With such a big deviation the impact can never be accurate ad long range. That’s why I think something is not right. By the way my barrel is 600mm.

 

[Yo]

90 bar is a perfect start (and finish in most cases)

 

[sniperlabyo]

That’s Normal and most noticeable when at high power. The reg screw and piston passages hole is only about .10mm or size or one wire brush size so that’s the high pressure air sound passing through to refill the reg plenum. 


Ernest 

 

[sniperlabyo]

Its all about tuning to get the ES lower! Need to know your reg pressure, PW and PW preload valve adjuster setting and spring wire size used, ammo used and speed??? Sounds like you are over powering the reg pressure. Seen some issues with macro metal partially blocking the reg passages hole. If tuning doesn’t cure the high ES may have to look into that. The impact has one of the lowest ES when tuned properly thats why they won most Top 5 100y events that said in the final about 65% are impact so really I’m competing with an impact.


Ernest

 

[Chuck-in-Ohio]

I noticed this also when PP is filling.

Is there a standard bar reg setting from the factory? 

.22 ,700 mm barrel.

Just wondering .

Thanks

Where I am at currently-

Impact X .22 700 MM barrel

Power plenum installed

Barrel port and probe mod (flared only, no pin probe)

Power Wheel slider gap adjusted to 16MM or .630 inch on Max setting

Valve adjuster 4 lines out

22Gr. FX Hybrid slugs average 940 with reg. set at 105 bar.



Previously-

Everything same same minus Power Plenum, 22 Gr. Hybrids averaged 890.





Now sounds wheezy after shot while plenum fills, and accepted as normal. I verified that the rifle leaks nary a single bar of pressure over a weeks time, so it is what it is.

In stock form, reg was set a t 110 bar out of the box.

 

[lvc]

Power plenum is filling know in a constant rate. I changed de reg pressure from 85 to about 92 93 bar. De hammer spring gap was 22,3 mm.... changed to 22,0 mm. speed with new setting. pellet jsb 18,13 gr .22 speed 858 fps. Shooting from 45 yards in the same hole until the poi shift. Cause: The hammer tension screw is creeping back after a few shots. Question: Is it normal to loctite the hammer tension adjustable screw. 
And thanks for all the info so far.

 

[Chuck-in-Ohio]

Yes, you can loctite the screw to keep it from moving.

Use low strength loctite, or a dab of nail polish to secure it so that it can be re adjusted in the future if you so desire.