Power Plenum on .25 cal., 600mm slug liner and 33.5gr NS slug

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Powerbroker

Powerbroker

Member
Jul 27, 2019
271
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Metro Manila~Quezon City, Philippines
Hello everyone! SOS! :)

Got my Power Plenum kit for FX impact x a few days ago from Krale. With the stock impact x, PP and a 135reg pressure (bottle is at 250 to 200bar), valve at 4th line and Max power wheel (little or no slack with the adjeustment screw), i can only get 881 fps on the NS 33.5gr.  If i will increase the reg pressure to 145bar, the fps drops to 820. 

The installation from Krale youtube video help me install the PP KIT. 

What went wrong? Is it what it is? I still have 3 boxes of 33.5gr NS that will be sent for sale if i can't get the gun to sling the 33.5gr at 920fps without modifications or machining.




 
You put the hammer weight in? and not running the C3 bumper plus the new hammer? If you back off the little adjustment screw does the speed go down? If you did install the hammer weight maybe its overwhelming the valve and its closing too fast with the hammer weight and so much spring.
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Glem,

I did put in the hammer weight. I opened the gun again twice just to make sure the hammer or the springs were not interchanged. There is dedicated C3 already, no more C3. I was thinking about the valve closing too fast because increasing the reg pressure from 130 to 145bar (valve adjustment-4th line and the hammer wheel- max) will decrease the fps to 820fps. 

I notice though, that in the Krale video "how to install", the hammer seat is not fully screwed in to keep a certain measurement of 6 to 6.5mm between the front of the hammer seat to the front of the housing. But that is too minimal.
 
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Did you lower the reg to 110-115 bar ?
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Hi Mike. This is the process. Valve is at 4th line. I started at 110b with 3 wheel tension. Then i have adjusted the wheel one at at time to Max. Then the regulator is adjusted 5 bar at a time until 135 bar. the fps will rise up to 881. I get 881fps with 5 strings. very consistent. But when i turn it more from 140 to 150bar, the fps will drop.

Thank you for taking time to post. 
 
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I have the same problem, i had to do some modyfications to get close to what i was expecting.

Mine was falling in fps after 130 bars so i had to put in the 57mm hammer spring. I am trying to shoot 25gr at 1000fps and iam just only getting that, and turning up the reg dossent really give much more speed.

From 130 bars to 150 bars it goes from 1000 fps to 1032fps..



how do they shoot 36gr at 1000fps .22 in all there videos and say this is what you get if you buy the PP

i have one question fx is advetition that you can get up to 70 fpe in the .22 stock! Can any of you guys get close to that?
 
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I have the same problem, i had to do some modyfications to get close to what i was expecting.

Mine was falling in fps after 130 bars so i had to put in the 57mm hammer spring. I am trying to shoot 25gr at 1000fps and iam just only getting that, and turning up the reg dossent really give much more speed.

From 130 bars to 150 bars it goes from 1000 fps to 1032fps..



how do they shoot 36gr at 1000fps .22 in all there videos and say this is what you get if you buy the PP

i have one question fx is advetition that you can get up to 70 fpe in the .22 stock! Can any of you guys get close to that?
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This is my conclusion. If you have a 25 cal and you want to buy a PP so you can shoot a slug more than 30 gr at a stable speed of 920fps or more, forget it. It won't happen unless you do some machining or replacing of parts. You will end up shooting pellets which must have an fps that is less 900fps to be stable and accurate. In that case, you can shoot a pellet at 900 with the stock plenum of MKI or MK2.

In my case, i will be back shooting pellets and the PP's benefit is just an additional shot per fill of the bottle.

Correct me if i am mistaken. 
 
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The new valve return spring is thick and very long and intended for the low power stuff and/or using low reg pressures, at the 4th line on the valve adjuster you are already loosing a lot of speed so try again with the valve adjuster just past the rubber o-ring without it hitting the shroud.

For shooting with the heavier slugs at higher pressures you can shorten the new thick spring, make one from the original thinner spring of use no spring at all like I do so there's less spring tension trying to close the valve.

The whole idea of moving the valve return spring to the valve adjuster is that you can experiment with it without taking the Impact apart, would be nice though if the Impact already came with a couple of different springs in the box to play with. Maybe the custom part makers can provide some custom springs.
 
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With tha

I have opened up the tranfer ports, lighter valve adjuster spring and shortend and the longer 57mm hammer spring and a 700mm barrel. And still not power enough.
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With that setup you should be able to catapult the 34gr MKII at a scourging 320mps / 1050fps at 170 bar and 305mps / 1000fps with the 38.5gr NSA slugs.

Overnight the Impact became my most powerful air rifle surpassing my .22 Huben K1, .25 RAW LRT and the .22 Edgun R5M. I've tested the latest .25 Daystate Safari a few weeks ago and it also doesn't hold a candle against the Impact with the Power Plenum.

The only rifles that can surpass it in power are those built for big bore powder burner calibers like the Texan, Hammer, etc which can shoot 308, 45, 50, etc.
 
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The new valve return spring is thick and very long and intended for the low power stuff and/or using low reg pressures, at the 4th line on the valve adjuster you are already loosing a lot of speed so try again with the valve adjuster just past the rubber o-ring without it hitting the shroud.

For shooting with the heavier slugs at higher pressures you can shorten the new thick spring, make one from the original thinner spring of use no spring at all like I do so there's less spring tension trying to close the valve.

The whole idea of moving the valve return spring to the valve adjuster is that you can experiment with it without taking the Impact apart, would be nice though if the Impact already came with a couple of different springs in the box to play with. Maybe the custom part makers can provide some custom springs.
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Bush, spot on. The valve adjuster is hitting the fix shroud. Look at the picture. I will not cut the return spring but i will use the old hammer spring. This might do the trick. But it might be too strong to damage the dedicated bumper. 
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I have opened up the tranfer ports, lighter valve adjuster spring and shortend and the longer 57mm hammer spring and a 700mm barrel. And still not power enough.
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You are killing me. I have no options left. We both made a mistaken belief or conclusion out of the youtubers before we bought the PP? Note: we made a mistaken belief. I am not accusing anyone here of misrepresentation. 
 
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