Fx impact .30 low fps

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blackswor

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Dec 7, 2016
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Hello i apologize in advance for my english because i am from Italy.
i have some issues reaching the advised speed and energy for my rifle, my settings are:
wheel on max (removed play with rowe guide)
valve on 4
regulator on 140(ish)
pellets jsb Kings 44gr

i only reach about 830fps and so around 90joule and not the 110 (ish) i read about.
the rifle shoots good i am only afraid there is something wrong because of this results.
thanks in advance for any suggestions
 
These numbers are from my notes when I chronographed a couple weeks ago. 

FX Boss
JSB .30 50.15gr 38 shots 
Max 859
Min 833
Avg 839

JSB .30 44.75gr 37 shots
Max 893
Min 870
Avg 877

FX Impact regulator @150 Bar
JSB King 44.75 .30 cal
On max power
Max 855
Min 840
Avg 847

On 5 power
Max 818
Min 797
Avg 808

JSB King Heavy 50.15 .30 cal
On max power
Max 814
Min 803
Avg 808

On 5 power
Max 779
Min 762
Avg 770
 
Upvote 0
I like both but to be honest the Boss has been sitting in the safe. The Impact is just more fun to shoot. 
The Boss is a very solid gun and its a little more accurate and powerful. Also next to no maintenance. Fill and shoot. 
The Impact has a bigger magazine and more shots per fill. It had some issues that were resolved by AOA promptly.
Those issues:
Bent set screw- sent me a new one(and everybody else)
50 Bar inaccurate bottle gauge- sent a new gauge and I installed it (now within 5 bar of fill tank and regulator gauge)
.25 barrel was not accurate- sent the barrel in and they polished and cleaned it (def more accurate)
It also needs more minor periodic maintenance such as tightening hex and thumb screws. Speaking of that the power wheel tension screw was a little loose and I tightened it up and rechronographed it. It's about 7-15 fps faster now than the number posted above. 
 
Upvote 0
"HavocX"I can't get my .25 cal to shoot JSB King Heavys 33.95gr over 830fps. I see others are getting 860+fps.
Reg is around 145 and valve spring is at 4th line.
Click to expand...
That's not bad for JSB heavies. It's over 50fpe which is right for a 25cal. 

Other than a slight change in trajectory, you would gain nothing useful from making it 860fps instead of 830. You would make it louder though.
 
Upvote 0
"HavocX"I can't get my .25 cal to shoot JSB King Heavys 33.95gr over 830fps. I see others are getting 860+fps.
Reg is around 145 and valve spring is at 4th line.
Click to expand...
Does the metal rectangle next to power wheel jiggle on max or is it tight? Also, are you sure your gauge is fairly accurate? I just got a new bottle gauge, the old one was 50 Bar off. Those little gauges aren't the best. 
I'm at 150 BAR and getting about 870-880 fps with .25 heavies. 
 
Upvote 0
"7deuce"
"HavocX"I can't get my .25 cal to shoot JSB King Heavys 33.95gr over 830fps. I see others are getting 860+fps.
Reg is around 145 and valve spring is at 4th line.
Click to expand...
Does the metal rectangle next to power wheel jiggle on max or is it tight? Also, are you sure your gauge is fairly accurate? I just got a new bottle gauge, the old one was 50 Bar off. Those little gauges aren't the best. 
I'm at 150 BAR and getting about 870-880 fps with .25 heavies.
Click to expand...
Ahh it appears the set screw for the power wheel had loosened up and gave up some slack. Snugged it back up to max and now shooting 860-870 with heavies..... but sadly another issue popped up. Left the rifle all weekend, checked today and the reg pressure had climbed up 20-30 BAR. Took some dry fire shots and it settled back down to the 140 area. Will check it again tomorrow to see if it moves again.

 
Upvote 0
"HavocX"
"7deuce"
"HavocX"I can't get my .25 cal to shoot JSB King Heavys 33.95gr over 830fps. I see others are getting 860+fps.
Reg is around 145 and valve spring is at 4th line.
Click to expand...
Does the metal rectangle next to power wheel jiggle on max or is it tight? Also, are you sure your gauge is fairly accurate? I just got a new bottle gauge, the old one was 50 Bar off. Those little gauges aren't the best. 
I'm at 150 BAR and getting about 870-880 fps with .25 heavies.
Click to expand...
Ahh it appears the set screw for the power wheel had loosened up and gave up some slack. Snugged it back up to max and now shooting 860-870 with heavies..... but sadly another issue popped up. Left the rifle all weekend, checked today and the reg pressure had climbed up 20-30 BAR. Took some dry fire shots and it settled back down to the 140 area. Will check it again tomorrow to see if it moves again.
Click to expand...
Ernest Rowe is responsible for me learning that little gem. I need to tighten it every other tin of pellets. As far as the regulator, I haven't had that issue. I would call AOA just to be safe. 
 
Upvote 0
"Motive410"mag_de_mars,
My Impact manual warns: never set regulator pressure above 150 bar or below 100 bar. Learn what pellet velocity groups best for your gun. 700mm barrels are more efficient. Tune for accuracy, then efficiency.
I might consider a 700 mm STX barrel kit designed for slugs. My ST barrel is better than I am...MK II @ 830 FPS.


I agree with you totally, i already modified washer stack like weatherby and i can push a lot higher than 150 bars, my search is only curiosity, i think the most important with the 700mm is the valve opening 
thank you Motive410
and yes my st is far far better than me too ;-)

Click to expand...
 
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