NPAS and HPA

[danf1234]

I have 4 TM MWS variants that all have Federal Concepts NPAS valves, but I have gone done the HPA route and bought adapters from airtac. 
question I have is should I change the NPAS valve back to standard as I am seeing a 10 fps fluctuation which I wasn’t expecting with HPA?

[Adolf Hamster]

It could be worth trying.

 

Although you're gonna have X psi requirement to get a good cycle, which might put you over the limit so you'd need some method of dropping it back down.

 

Shimming a standard rocket valve does the same thing as an npas, and might be more repeatable, or a shorter inner barrel can do the job too (dont worry if it's shorter than the outer)

[GiantKiwi]

How old are your FEDA's? This sounds like the old 3D printed resin ones which really, really don't like staying consistent as the adjustment screw has a tendency to walk from them as threadlock can't bind to the resin.

Edited Monday at 22:32 by GiantKiwi
clarity

[danf1234]

They are the older 3D printed ones yes

[LMKipper]

The issue you will have is that you'll often need a fairly high pressure for the rifle to cycle consistently. Airsoft green gas/propane is around 140psi at room temperature, so that's a good place to start with a reg setting, then see if you need the NPAS to bring it down to playable limits.