FX Impact .25 with JSB MkII 33.95gr -- what FPS are you getting?

Set your power wheel to 4 and 5 and chrono it. And maybe your power wheel set screw is loose.

You need to have the reg as close to 150bars as possible. Though I would not want to use their gauge to determine that.

Do you just want more speed or is it not accurate? From what Ted (holdover ted) has shown that slower speeds seem to be more consistent with the heavies. His Impact seemed to be more stable/accurate at 830 fps (+/- 10 fps for all other impacts).

It could be possible bad o ring... lots of them on the Impact.
What is your shot count like? beginning pressure, end pressure and # shots.

-- Your Power wheel set to 4-5 and FPS decrease? 

How far way do you shot from your chrony?

Either way to get those higher FPS you need your regulator as close to 150bars as possible.

I had mine at 880-890 fps with 33.95 and everything maxed out but I lowered my regulator from 150 to about 142. I was getting way too many fliers. I haven't chronographed my new setting yet but it's definitely way more accurate. More power is nice but if you can't hit your target, what's the point. 

Max I get is 890 fps. Factory settings on regulator and adjustment knob, wheel on max and set screw adjusted for minimum slop. I seem to get better groups at 850 fps or less.

I just lowered my regulator to about 147 BAR( according to gauge) from just over 150 BAR. At my old setting I was getting avg 886 fps on MAX with 33.95 grains. I was getting to many fliers with the old setting. I got 4 full mags on 1 fill(250 to 150) and I'm hoping to squeeze 1 more mag out with new settings. 
My new averages for 33.95 are:
MAX 861
5 857
4 841
3 806

So far my best results are with setting 4

Mine shoots 835 fps at "max", 807 fps on number 5. Stock manometer roughly 140 (awaiting Wika upgraded gauges)

Lol. Me too

I am shooting JSB Heavy MK I on P.W. setting "A" and valve =4 for an ave. velocity of 857 fps. 
On Max it is between 861 and 865 fps. 
Best accuracy on setting A.
I have my regulator set at what looks like 149 bar on the gauge......... but who knows what it really is.

It could be your breech o-ring have you inspected that. Mine was blowing a puff of air on my cheek and was quite a bit louder. I looked in the barrel and the o-ring was completely missing. Much easier to change that than the valve stem oring. Hope you get her fixed good luck. 

I seem to chrony mine ever other day and MK1's and MK2 valve spring on 4 PW on 5 I was getting consistently 825-835 all last week, don't know if my regulator is finally settling down because it shot 850-865 yesterday on PW5 no adjustments made, nothing loosen or tighten up. groups where best at 825 so i may bump it down to four and shoot some more groups, but today I shot a clip at 50 yards and got 12 pellets in a 1/4 of inch, 3 within 1/2 and 2 within an inch: So all pellets where within an inch but if i got ride of 5 it would of been fantastic. Whens are like 35-40 right in my face today.

"Ginuwine1969"..., but today I shot a clip at 50 yards and got 12 pellets in a 1/4 of inch, 3 within 1/2 and 2 within an inch: So all pellets where within an inch but if i got ride of 5 it would of been fantastic. Whens are like 35-40 right in my face today.

Click to expand...

What? 12 pellets at 50 yards at a 1/4 inch into a 35-40 mph wind...

Wind was straight north to so (no a cross wind) and I check the weather gusting 19 mph just felt like more

Drbytes, I agree with TXBoy....first thing to check is the breech o-ring located in the barrel. Always start with the easiest thing. My Marauder used to blow them out now and again. Take a flashlight and it should be immediately evident if its there or not. Clean out the o-ring grove, use a wood dowel from muzzle end, place the lubed, replacement o-ring on your thumb then against the dowel and mash the whole thing into the barrel. It should guide right in with a little maneuvering. Hoping it's that. Quick easy fix.

Hey, I had the same issue with not getting anywhere near the 830 fps with the 33,95 gr. JSB MK IIs recommended by "Ted Holdover" with all settings maxed out and a regulator pressure set at 140 bar (read of the gage). I contacted FX in Sweeden and they suggested to set the power wheel at the max position to 15,0 mm (+/- 0,5 mm) as for a .30 cal (my .25 cal was at the factory setting of 18.0 mm). I increased my mozzle velocity conciderably and even with my regulator pressure now set to 125 bar (gage reading) I achieve 924 fps with everything maxed out. The grouping at 50 m is way too bad (5-8 cm but sometimes much less) but I think that it is a barrel issue which. I will soon get a new barrel from FX and I will see if it is ok!