Low fps fx impact.22 + power plenum

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poperboy

Member
Feb 9, 2020
12
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France
Hello everybody,

first, i m sorry for my english because i m french and i leave at monaco so i try to explain my problem.

i have a fx impact mk1 caliber .22 with smooth twist x barrel 700 mm pellets liner, i have install the kit upgrade power plenum and i’ve changed my regulator with à huma air regulator high pressure gen1 and i shot with fx hybrid slugs.

my problem is that, i have the regulator at 130 bar and i shoot them slugs at 850fps. I unscrew the screw of the regulator to up the pressure at 135 bar, i shoot i have Max 907fps and if i continue to unscrew the regulator the dos goes down like if i put 150bar in the regulator i shoot at 880fps and more i io the regulator pressure less are the fps... i don’t know why ... 

i would like to have 950/1000fps :-(

anyone can help me or tell me why ?

thank a lot 
 
It sounds like you dont have enough hammer spring to start with for the regulator setting. 2nd you may need to open the transfer port up but I try every else first. It's tunning is totally different from the old tunning. Try lowering your regulator back down to around 100 bar. Turn your hammer spring adjuster in tight on max. Open your valve adjustment out to 4th line. Try and use your old hammer spring. I'm noticing the new hammer spring tops out at 115-120 bar

Slowly shoot over the cronie 3-5 shoots bumping your regulator up 3-5 bar until you each the speed your looking for. Check your pellet prob and make sure it set right. It's not covering the transfer port. If my memory is correct the measurement off the rear block is 44.5mm-44.7mm please double check.

Once you get the speed you like. Use the VA to stablize the FPS but Turing it in 1/8 of a turn every 5-10 shots until it's stable. I'm seeing it like around line #2

1000FPS is a high reach good luck.

Cheers
 
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Thanks at all for replying :)

just to inform you, my wheel is on max and the valve is at the 4th Line .

i’ve learned the Hammer sprint like you tell me is maybe too low because if my memory is good, in the original plenum, the hammer spring is more long than the hammer spring of the kit power plenum so first i want to try with this configuration at 110/120 bar at the regulator in that configuration. If i have bad result, i pull out the hammer spring of the kit power plenum and i replace it by the original hammer spring a little bit more long to see if there is a différence. After that i want to control in the same time the weight of the original hammer with the hammer of the kit power plenum to see if there a biggest diference :)

let see it and i tell you if it’s better or not ;-)
 
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There is a hammer spring adjuster behind the power wheel. It has an Allen screw that pre-loads the adjuster. You can adjust preload there. I would put the original hammer spring back in. 



My 22 crown shoots well over 1200fps if I want. It shoots crow magnums 21gr at over 1000fps in a 500mm barrel. 21gr slugs I have gotten to 1111fps in my 700mm barrel.
 
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Yes the allen screw is on Max like that i know the tension of the hammer spring is on the top :) i have changed the hammer spring to thé original ;-) i send you the picture after like that you can see the little diference and i have a lot of news about thé alignement of the out of the pressure regulate . Like that you can see the diameter of all and modify the pieces who pull in the pellets
 
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1581356179_12630554465e41949344f1b8.89361993_BE45B813-C5A1-44CE-ABE3-D97D0A22C9F5.jpeg

look at the little diference about at the left the hammer spring of the kit power plenum and at the right the original hammer spring :)

i have put now the original hammer spring
 
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I ve check all holes about the Pellet probe and .... the hole where go out the regulate pressure is about 7mm and the distance about this hole and the limit hard where you put the pellets charger is about 7.50 mm.

the hole of my pellets probe is 4.4mm in caliber.22 so i’ve checked the good position about thé enter of this pellets probe like that it’s perfecly on the out hole regulated pressure so my conclusion to tunes thé pellets probe is to do a higher hole BUT pull over thé metal behind and not in front pellets to have a Max larger of entry air. I think i can put over 1.2mm in the longer.

i gove you sole pictures and sorry for my picture i do that really quickly ahahah


 
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So ....

i’ve start my shots at 100 bar and i were at 890fps .... always my wheel at Max and at the 4 line. i up the pressure at 110 bar and i were at 950/960 fps ... i ve up at 115/120 bar and i ´ve got 980/985 fps.

After that i’ve tried to 125/130 bar and my fps are go down at 950/960 fps so i’ve stopped because:

first I think i need to have 15/120 bar max like you telling me and

second, i have a extra high pressure regulator huma air gen1 who work if i’m right at 145/180 bar and i would like to modified it in high pressure regulator who work at 80-145 bar because i dont need now with thé power plenum to have an extra high pressure regulator and maybe i dont have good result because he ( the regulator extra high pressure ) work with at minimum 150bar.

so ... i happy about thé result that i’ve got but need to see if it were better with them changement :)))


 
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Today i’ve shot with my regulator high pressure huma air (80-145bar)

it’s à little fastidious because when i up a little thé pressure with the small scrue, my regulate pression go up at 140/145 bar and after 4/5 shot, turn at 100/105 bar .... i dont know why, but it’s like that (maybe thé power plenum do that) so i need to stop because i have no Time to continue but i’ve got at 130/140 bar à velocity of my fx hybrid slugs .22 at 1140 fps !!!! 
so i think i need to continue like that to have at the final a real and good regulated pression who dont turn down at 120/130bar to obtain thé 980 fps like i want :)))

for thé moment i’m a little happy about them results :)
 
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Perfect !!!!

i have now with my fx impact mk1 with power plenum, original spring hammer and not the spring hammer with thé kit power plenum who is smaller than thé original, tune my Pellet probe and power transfer of the barrel, 700mm smooth twist x barrel with pellets barrel, regulator huma air extra high power, i have 110 bar regulated and i can now shot fx hybrid slugs .22 at a velocity of 980 fps +/- 4 fps !!!

now that i have à stable fps at 980 fps like i want, i need to see thé accurary :))))


 
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