Tuning FX Impact Mk2 FPS same regardless of setting issue

[Tnp]

Fx Impact Mk2 in .25 600mm with DT and slug kit

Valve @ line 4

Regulator 118 Bar

Gun is shooting 25.39g pellets between 970-990FPS regardless of how much or how little hammer spring tension and regardless of where it's at on the power wheel. I'm assuming this has something to do with the hammer spring as this was tuned for a .30 cal before I got it.

What do you guys the issue is?

 

[corny]

did u adjust the reg? HS should have been tuned to the reg pressure. 


In front of the power wheel, there’s a place where u can insert Allen or hex key. With your power wheel on max, and the gun de-cocked…start backing that out. 

 

[Tnp]

did u adjust the reg? HS should have been tuned to the reg pressure. 


In front of the power wheel, there’s a place where u can insert Allen or hex key. With your power wheel on max, and the gun de-cocked…start backing that out. 

Yep, Allen screws was screwed all the way in until the power wheel could barely move on max setting. I even tried backing the Allen screw all the way out so see if the speed changed in which it did not.

 

[wWilliam]

That sounds about right for a stock mk2

 

[Tnp]

Ok, I think my previous explanation wasn't very clear. 

So my gun is shooting between 970-990fps. It doesn't matter what setting of the power wheel I'm on, Min-Max, the fps is still between 970-990fps. It doesn't matter how far in or out the allen screw is for the hammer, it's still shooting between 970-990fps.

What is causing this to happen?

 

[corny]

Have u adjusted the reg pressure since u got the gun?

does the gun have the slug/power kit installed? (Spacers on the hammer spring? 


You should be able to farther tune down the gun on 118 reg pressure. 

 

[corny]

If u have the dual transfer port, HS spacers, and slug probe. 
my experience is these mods don’t work well for lower tunes.

the HS spacers creates to much preload on the hammer spring, so I couldn’t set it low enough. 

The dual ports let the gun breath to much, and doesn’t create back pressure to help close the valve. Not efficient. Your also going to have issue getting the ES nice and low. 

 

[Tnp]

Thanks Corny, that makes a lot more sense. I'm going to remove the washers I installed from the slug power kit and go from there. And as far as the dual transfer port, I'm using the lower power side.

Curious question though, does the Impact Mk2 in .30 caliber have the same Hammer Spring as the .25 version?

 

[Glem.Chally]

Thanks Corny, that makes a lot more sense. I'm going to remove the washers I installed from the slug power kit and go from there. And as far as the dual transfer port, I'm using the lower power side.

Curious question though, does the Impact Mk2 in .30 caliber have the same Hammer Spring as the .25 version?

Yes

 

[dannya1a]

turn you front valve adjuster all they way in. running at 4 lines is wide open. close it down and you'll now have control with the power wheel. I just noticed this today on mine as well. there is a small window in the 1 to 2 line area on the front valve with all that installed on the MK2. I'm currently changing from .25 cal to .22 cal and was having a hard time getting an efficient tune when I noticed this same phenomenon